Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <guss80@gmail.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes#8444
This patch introduces 3 new histograms per metaslab. These
histograms track segments that have made it to the metaslab's
space map histogram (and are part of the spacemap) but have
not yet reached the ms_allocatable tree on loaded metaslab's
because these metaslab's are currently syncing and haven't
gone through metaslab_sync_done() yet.
The histograms help when we decide whether to load an unloaded
metaslab in-order to allocate from it. When calculating the
weight of an unloaded metaslab traditionally, we look at the
highest bucket of its spacemap's histogram. The problem is
that we are not guaranteed to be able to allocated that
segment when we load the metaslab because it may still be at
the freeing, freed, or defer trees. The new histograms are
used when we try to calculate an unloaded metaslab's weight
to deal with this issue by removing segments that have would
not be in the allocatable tree at runtime. Note, that this
method of dealing with this is not completely accurate as
adjacent segments are not always consolidated in the space
map histogram of a metaslab.
In addition and to make things deterministic, we always reset
the weight of unloaded metaslabs based on their space map
weight (instead of doing that on a need basis). Thus, every
time a metaslab is loaded and its weight is reset again (from
the weight based on its space map to the one based on its
allocatable range tree) we expect (and assert) that this
change in weight can only get better if it doesn't stay the
same.
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes#8358
Initially, metaslabs and space maps used to be the same thing
in ZFS. Later, we started differentiating them by referring
to the space map as the on-disk state of the metaslab, making
the metaslab a higher-level concept that is metadata that deals
with space accounting. Today we've managed to split that code
furthermore, with the space map being its own on-disk data
structure used in areas of ZFS besides metaslabs (e.g. the
vdev-wide space maps used for zpool checkpoint or vdev removal
features).
This patch refactors the space map code to further split the
space map code from the metaslab code. It does so by getting
rid of the idea that the space map can have a different in-core
and on-disk length (sm_length vs smp_length) which is something
that is only used for the metaslab code, and other consumers
of space maps just have to deal with. Instead, this patch
introduces changes that move the old in-core length of the
metaslab's space map to the metaslab structure itself (see
ms_synced_length field) while making the space map code only
care about the actual space map's length on-disk.
The result of this is that space map consumers no longer have
to deal with syncing two different lengths for the same
structure (e.g. space_map_update() goes away) while metaslab
specific behavior stays within the metaslab code. Specifically,
the ms_synced_length field keeps track of the amount of data
metaslab_load() can read from the metaslab's space map while
working concurrently with metaslab_sync() that may be
appending to that same space map.
As a side note, the patch also adds a few comments around
the metaslab code documenting some assumptions and expected
behavior.
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes#8328
The range_tree_verify function looks for a segment in a
range tree and panics if the segment is present on the
tree. This patch gives the function a more descriptive
name.
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes#8327
Most callers that need to operate on a loaded metaslab, always
call metaslab_load_wait() before loading the metaslab just in
case someone else is already doing the work.
Factoring metaslab_load_wait() within metaslab_load() makes the
later more robust, as callers won't have to do the load-wait
check explicitly every time they need to load a metaslab.
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes#8290
PROBLEM
========
The first access to a block incurs a performance penalty on some platforms
(e.g. AWS's EBS, VMware VMDKs). Therefore we recommend that volumes are
"thick provisioned", where supported by the platform (VMware). This can
create a large delay in getting a new virtual machines up and running (or
adding storage to an existing Engine). If the thick provision step is
omitted, write performance will be suboptimal until all blocks on the LUN
have been written.
SOLUTION
=========
This feature introduces a way to 'initialize' the disks at install or in the
background to make sure we don't incur this first read penalty.
When an entire LUN is added to ZFS, we make all space available immediately,
and allow ZFS to find unallocated space and zero it out. This works with
concurrent writes to arbitrary offsets, ensuring that we don't zero out
something that has been (or is in the middle of being) written. This scheme
can also be applied to existing pools (affecting only free regions on the
vdev). Detailed design:
- new subcommand:zpool initialize [-cs] <pool> [<vdev> ...]
- start, suspend, or cancel initialization
- Creates new open-context thread for each vdev
- Thread iterates through all metaslabs in this vdev
- Each metaslab:
- select a metaslab
- load the metaslab
- mark the metaslab as being zeroed
- walk all free ranges within that metaslab and translate
them to ranges on the leaf vdev
- issue a "zeroing" I/O on the leaf vdev that corresponds to
a free range on the metaslab we're working on
- continue until all free ranges for this metaslab have been
"zeroed"
- reset/unmark the metaslab being zeroed
- if more metaslabs exist, then repeat above tasks.
- if no more metaslabs, then we're done.
- progress for the initialization is stored on-disk in the vdev’s
leaf zap object. The following information is stored:
- the last offset that has been initialized
- the state of the initialization process (i.e. active,
suspended, or canceled)
- the start time for the initialization
- progress is reported via the zpool status command and shows
information for each of the vdevs that are initializing
Porting notes:
- Added zfs_initialize_value module parameter to set the pattern
written by "zpool initialize".
- Added zfs_vdev_{initializing,removal}_{min,max}_active module options.
Authored by: George Wilson <george.wilson@delphix.com>
Reviewed by: John Wren Kennedy <john.kennedy@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: loli10K <ezomori.nozomu@gmail.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Richard Lowe <richlowe@richlowe.net>
Signed-off-by: Tim Chase <tim@chase2k.com>
Ported-by: Tim Chase <tim@chase2k.com>
OpenZFS-issue: https://www.illumos.org/issues/9102
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/c3963210ebCloses#8230
In order to validate the gang block code ztest is configured to
artificially force a fraction of large blocks to be written as
gang blocks. The default setting chosen for this was to
write 25% of all blocks 32k or larger using gang blocks.
The confluence of an unrealistically large number of gang blocks,
the aggressive fault injection done by ztest, and the split
segment reconstruction logic introduced by device removal has
resulted in the following type of failure:
zdb -bccsv -G -d ... exit code 3
Specifically, zdb was unable to open the pool because it was
unable to reconstruct a damaged block. Manual investigation
of multiple failures clearly showed that the block could be
reconstructed. However, due to the large number of damaged
segments (>35) it could not be done in the allotted time.
Furthermore, the large number of gang blocks was determined
to be the reason for the unrealistically large number of
damaged segments. In order to make this situation less
likely, this change both increases the forced gang block
size to 64k and reduces the frequency to 3% of blocks.
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#8080
This patch fixes a small issue where the zil_check_log_chain()
code path would hit an EBUSY error. This would occur when
2 threads attempted to call metaslab_activate() at the same time.
In this case, the "loser" would receive an error code which should
have been ignored, but was instead floated to the caller. This
ended up resulting in an ENXIO being returned from from
spa_ld_verify_logs().
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#8010
Recent changes in the Linux kernel made it necessary to prefix
the refcount_add() function with zfs_ due to a name collision.
To bring the other functions in line with that and to avoid future
collisions, prefix the other refcount functions as well.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Schumacher <timschumi@gmx.de>
Closes#7963
torvalds/linux@59b57717f ("blkcg: delay blkg destruction until
after writeback has finished") added a refcount_t to the blkcg
structure. Due to the refcount_t compatibility code, zfs_refcount_t
was used by mistake.
Resolve this by removing the compatibility code and replacing the
occurrences of refcount_t with zfs_refcount_t.
Reviewed-by: Franz Pletz <fpletz@fnordicwalking.de>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Schumacher <timschumi@gmx.de>
Closes#7885Closes#7932
Allocation Classes add the ability to have allocation classes in a
pool that are dedicated to serving specific block categories, such
as DDT data, metadata, and small file blocks. A pool can opt-in to
this feature by adding a 'special' or 'dedup' top-level VDEV.
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Alek Pinchuk <apinchuk@datto.com>
Reviewed-by: Håkan Johansson <f96hajo@chalmers.se>
Reviewed-by: Andreas Dilger <andreas.dilger@chamcloud.com>
Reviewed-by: DHE <git@dehacked.net>
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: Gregor Kopka <gregor@kopka.net>
Reviewed-by: Kash Pande <kash@tripleback.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes#5182
Relax allocation throttling for ditto blocks. Due to random imbalances
in allocation it tends to push block copies to one vdev, that looks
slightly better at the moment. Slightly less strict policy allows both
improve data security and surprisingly write performance, since we don't
need to touch extra metaslabs on each vdev to respect the min distance.
Sponsored by: iXsystems, Inc.
Authored by: mav <mav@FreeBSD.org>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://illumos.org/issues/9751
FreeBSD-commit: https://github.com/freebsd/freebsd/commit/8253837ac3Closes#7857
Use METASLAB_WEIGHT_CLAIM weight to allocate tertiary blocks.
Previous use of METASLAB_WEIGHT_SECONDARY for that caused errors
later on metaslab_activate_allocator() call, leading to massive
load of unneeded metaslabs and write freezes.
Authored by: mav <mav@FreeBSD.org>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://illumos.org/issues/9738
FreeBSD-commit: https://github.com/freebsd/freebsd/commit/63e7138Closes#7858
Overview
========
We parallelize the allocation process by creating the concept of
"allocators". There are a certain number of allocators per metaslab
group, defined by the value of a tunable at pool open time. Each
allocator for a given metaslab group has up to 2 active metaslabs; one
"primary", and one "secondary". The primary and secondary weight mean
the same thing they did in in the pre-allocator world; primary metaslabs
are used for most allocations, secondary metaslabs are used for ditto
blocks being allocated in the same metaslab group. There is also the
CLAIM weight, which has been separated out from the other weights, but
that is less important to understanding the patch. The active metaslabs
for each allocator are moved from their normal place in the metaslab
tree for the group to the back of the tree. This way, they will not be
selected for use by other allocators searching for new metaslabs unless
all the passive metaslabs are unsuitable for allocations. If that does
happen, the allocators will "steal" from each other to ensure that IOs
don't fail until there is truly no space left to perform allocations.
In addition, the alloc queue for each metaslab group has been broken
into a separate queue for each allocator. We don't want to dramatically
increase the number of inflight IOs on low-end systems, because it can
significantly increase txg times. On the other hand, we want to ensure
that there are enough IOs for each allocator to allow for good
coalescing before sending the IOs to the disk. As a result, we take a
compromise path; each allocator's alloc queue max depth starts at a
certain value for every txg. Every time an IO completes, we increase the
max depth. This should hopefully provide a good balance between the two
failure modes, while not dramatically increasing complexity.
We also parallelize the spa_alloc_tree and spa_alloc_lock, which cause
very similar contention when selecting IOs to allocate. This
parallelization uses the same allocator scheme as metaslab selection.
Performance Results
===================
Performance improvements from this change can vary significantly based
on the number of CPUs in the system, whether or not the system has a
NUMA architecture, the speed of the drives, the values for the various
tunables, and the workload being performed. For an fio async sequential
write workload on a 24 core NUMA system with 256 GB of RAM and 8 128 GB
SSDs, there is a roughly 25% performance improvement.
Future Work
===========
Analysis of the performance of the system with this patch applied shows
that a significant new bottleneck is the vdev disk queues, which also
need to be parallelized. Prototyping of this change has occurred, and
there was a performance improvement, but more work needs to be done
before its stability has been verified and it is ready to be upstreamed.
Authored by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Alexander Motin <mav@FreeBSD.org>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Gordon Ross <gwr@nexenta.com>
Ported-by: Paul Dagnelie <pcd@delphix.com>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Porting Notes:
* Fix reservation test failures by increasing tolerance.
OpenZFS-issue: https://illumos.org/issues/9112
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/3f3cc3c3Closes#7682
Motivation
==========
The current space map encoding has the following disadvantages:
[1] Assuming 512 sector size each entry can represent at most 16MB for a segment.
This makes the encoding very inefficient for large regions of space.
[2] As vdev-wide space maps have started to be used by new features (i.e.
device removal, zpool checkpoint) we've started imposing limits in the
vdevs that can be used with them based on the maximum addressable offset
(currently 64PB for a top-level vdev).
New encoding
============
The layout can be found at space_map.h and it remains backwards compatible with
the old one. The introduced two-word entry format, besides extending the limits
imposed by the single-entry layout, also includes a vdev field and some extra
padding after its prefix.
The extra padding after the prefix should is reserved for future usage (e.g.
new prefixes for future encodings or new fields for flags). The new vdev field
not only makes the space maps more self-descriptive, but also opens the doors
for pool-wide space maps (expected to be used in the log spacemap project).
One final important note is that the number of bits used for vdevs is reduced
to 24 bits for blkptrs. That was decided as we don't know of any setups that
use more than 16M vdevs for the time being and we wanted to fit the vdev field
in the space map. In addition that gives us some extra bits in dva_t.
Other references:
=================
The new encoding is also discussed towards the end of the Log Space Map
presentation from 2017's OpenZFS summit.
Link: https://www.youtube.com/watch?v=jj2IxRkl5bQ
Authored by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <gwilson@zfsmail.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Gordon Ross <gwr@nexenta.com>
Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/90a56e6d
OpenZFS-issue: https://www.illumos.org/issues/9238Closes#7665
Details about the motivation of this feature and its usage can
be found in this blogpost:
https://sdimitro.github.io/post/zpool-checkpoint/
A lightning talk of this feature can be found here:
https://www.youtube.com/watch?v=fPQA8K40jAM
Implementation details can be found in big block comment of
spa_checkpoint.c
Side-changes that are relevant to this commit but not explained
elsewhere:
* renames members of "struct metaslab trees to be shorter without
losing meaning
* space_map_{alloc,truncate}() accept a block size as a
parameter. The reason is that in the current state all space
maps that we allocate through the DMU use a global tunable
(space_map_blksz) which defauls to 4KB. This is ok for metaslab
space maps in terms of bandwirdth since they are scattered all
over the disk. But for other space maps this default is probably
not what we want. Examples are device removal's vdev_obsolete_sm
or vdev_chedkpoint_sm from this review. Both of these have a
1:1 relationship with each vdev and could benefit from a bigger
block size.
Porting notes:
* The part of dsl_scan_sync() which handles async destroys has
been moved into the new dsl_process_async_destroys() function.
* Remove "VERIFY(!(flags & FWRITE))" in "kernel.c" so zhack can write
to block device backed pools.
* ZTS:
* Fix get_txg() in zpool_sync_001_pos due to "checkpoint_txg".
* Don't use large dd block sizes on /dev/urandom under Linux in
checkpoint_capacity.
* Adopt Delphix-OS's setting of 4 (spa_asize_inflation =
SPA_DVAS_PER_BP + 1) for the checkpoint_capacity test to speed
its attempts to fill the pool
* Create the base and nested pools with sync=disabled to speed up
the "setup" phase.
* Clear labels in test pool between checkpoint tests to avoid
duplicate pool issues.
* The import_rewind_device_replaced test has been marked as "known
to fail" for the reasons listed in its DISCLAIMER.
* New module parameters:
zfs_spa_discard_memory_limit,
zfs_remove_max_bytes_pause (not documented - debugging only)
vdev_max_ms_count (formerly metaslabs_per_vdev)
vdev_min_ms_count
Authored by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Richard Lowe <richlowe@richlowe.net>
Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
OpenZFS-issue: https://illumos.org/issues/9166
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7159fdb8Closes#7570
Minimal changes required to integrate the SPL sources in to the
ZFS repository build infrastructure and packaging.
Build system and packaging:
* Renamed SPL_* autoconf m4 macros to ZFS_*.
* Removed redundant SPL_* autoconf m4 macros.
* Updated the RPM spec files to remove SPL package dependency.
* The zfs package obsoletes the spl package, and the zfs-kmod
package obsoletes the spl-kmod package.
* The zfs-kmod-devel* packages were updated to add compatibility
symlinks under /usr/src/spl-x.y.z until all dependent packages
can be updated. They will be removed in a future release.
* Updated copy-builtin script for in-kernel builds.
* Updated DKMS package to include the spl.ko.
* Updated stale AUTHORS file to include all contributors.
* Updated stale COPYRIGHT and included the SPL as an exception.
* Renamed README.markdown to README.md
* Renamed OPENSOLARIS.LICENSE to LICENSE.
* Renamed DISCLAIMER to NOTICE.
Required code changes:
* Removed redundant HAVE_SPL macro.
* Removed _BOOT from nvpairs since it doesn't apply for Linux.
* Initial header cleanup (removal of empty headers, refactoring).
* Remove SPL repository clone/build from zimport.sh.
* Use of DEFINE_RATELIMIT_STATE and DEFINE_SPINLOCK removed due
to build issues when forcing C99 compilation.
* Replaced legacy ACCESS_ONCE with READ_ONCE.
* Include needed headers for `current` and `EXPORT_SYMBOL`.
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
TEST_ZIMPORT_SKIP="yes"
Closes#7556
ASSERT3U() could be NOP which then leads to having unused pointer *spa.
metaslab.c: In function 'metaslab_condense':
metaslab.c:2075:9: warning: unused variable 'spa' [-Wunused-variable]
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@osnexus.com>
Closes#7489
We should use zfs_dbgmsg instead of spa_dbgmsg. Or at least,
metaslab_condense() should call zfs_dbgmsg because it's important and
rare enough to always log. It's possible that the message in
zio_dva_allocate() would be too high-frequency for zfs_dbgmsg.
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Richard Lowe <richlowe@richlowe.net>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Patch Notes:
* Removed ZFS_DEBUG_SPA from zfs-module-parameters.5
OpenZFS-issue: https://www.illumos.org/issues/9236
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/cfaba7f668Closes#7467
Authored by: Matt Ahrens <Matt.Ahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Approved by: Garrett D'Amore <garrett@damore.org>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/9280
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/243952cCloses#7445
Mirrors are supposed to provide redundancy in the face of whole-disk
failure and silent damage (e.g. some data on disk is not right, but ZFS
hasn't detected the whole device as being broken). However, the current
device removal implementation bypasses some of the mirror's redundancy.
Note that in no case is incorrect data returned, but we might get a
checksum error when we should have been able to find the right data.
There are two underlying problems:
1. When we remove a mirror device, we only read one side of the mirror.
Since we can't verify the checksum, this side may be silently bad, but
the good data is on the other side of the mirror (which we didn't read).
This can cause the removal to "bake in" the busted data – all copies of
the data in the new location are the same, busted version, while we left
the good version behind.
The fix for this is to read and copy both sides of the mirror. If the
old and new vdevs are mirrors, we will read both sides of the old
mirror, and write each copy to the corresponding side of the new mirror.
(If the old and new vdevs have a different number of children, we will
do this as best as possible.) Even though we aren't verifying checksums,
this ensures that as long as there's a good copy of the data, we'll have
a good copy after the removal, even if there's silent damage to one side
of the mirror. If we're removing a mirror that has some silent damage,
we'll have exactly the same damage in the new location (assuming that
the new location is also a mirror).
2. When we read from an indirect vdev that points to a mirror vdev, we
only consider one copy of the data. This can lead to reduced effective
redundancy, because we might read a bad copy of the data from one side
of the mirror, and not retry the other, good side of the mirror.
Note that the problem is not with the removal process, but rather after
the removal has completed (having copied correct data to both sides of
the mirror), if one side of the new mirror is silently damaged, we
encounter the problem when reading the relocated data via the indirect
vdev. Also note that the problem doesn't occur when ZFS knows that one
side of the mirror is bad, e.g. when a disk entirely fails or is
offlined.
The impact is that reads (from indirect vdevs that point to mirrors) may
return a checksum error even though the good data exists on one side of
the mirror, and scrub doesn't repair all data on the mirror (if some of
it is pointed to via an indirect vdev).
The fix for this is complicated by "split blocks" - one logical block
may be split into two (or more) pieces with each piece moved to a
different new location. In this case we need to read all versions of
each split (one from each side of the mirror), and figure out which
combination of versions results in the correct checksum, and then repair
the incorrect versions.
This ensures that we supply the same redundancy whether you use device
removal or not. For example, if a mirror has small silent errors on all
of its children, we can still reconstruct the correct data, as long as
those errors are at sufficiently-separated offsets (specifically,
separated by the largest block size - default of 128KB, but up to 16MB).
Porting notes:
* A new indirect vdev check was moved from dsl_scan_needs_resilver_cb()
to dsl_scan_needs_resilver(), which was added to ZoL as part of the
sequential scrub work.
* Passed NULL for zfs_ereport_post_checksum()'s zbookmark_phys_t
parameter. The extra parameter is unique to ZoL.
* When posting indirect checksum errors the ABD can be passed directly,
zfs_ereport_post_checksum() is not yet ABD-aware in OpenZFS.
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Tim Chase <tim@chase2k.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Tim Chase <tim@chase2k.com>
OpenZFS-issue: https://illumos.org/issues/9290
OpenZFS-commit: https://github.com/openzfs/openzfs/pull/591Closes#6900
OpenZFS 7614 - zfs device evacuation/removal
OpenZFS 9064 - remove_mirror should wait for device removal to complete
This project allows top-level vdevs to be removed from the storage pool
with "zpool remove", reducing the total amount of storage in the pool.
This operation copies all allocated regions of the device to be removed
onto other devices, recording the mapping from old to new location.
After the removal is complete, read and free operations to the removed
(now "indirect") vdev must be remapped and performed at the new location
on disk. The indirect mapping table is kept in memory whenever the pool
is loaded, so there is minimal performance overhead when doing operations
on the indirect vdev.
The size of the in-memory mapping table will be reduced when its entries
become "obsolete" because they are no longer used by any block pointers
in the pool. An entry becomes obsolete when all the blocks that use
it are freed. An entry can also become obsolete when all the snapshots
that reference it are deleted, and the block pointers that reference it
have been "remapped" in all filesystems/zvols (and clones). Whenever an
indirect block is written, all the block pointers in it will be "remapped"
to their new (concrete) locations if possible. This process can be
accelerated by using the "zfs remap" command to proactively rewrite all
indirect blocks that reference indirect (removed) vdevs.
Note that when a device is removed, we do not verify the checksum of
the data that is copied. This makes the process much faster, but if it
were used on redundant vdevs (i.e. mirror or raidz vdevs), it would be
possible to copy the wrong data, when we have the correct data on e.g.
the other side of the mirror.
At the moment, only mirrors and simple top-level vdevs can be removed
and no removal is allowed if any of the top-level vdevs are raidz.
Porting Notes:
* Avoid zero-sized kmem_alloc() in vdev_compact_children().
The device evacuation code adds a dependency that
vdev_compact_children() be able to properly empty the vdev_child
array by setting it to NULL and zeroing vdev_children. Under Linux,
kmem_alloc() and related functions return a sentinel pointer rather
than NULL for zero-sized allocations.
* Remove comment regarding "mpt" driver where zfs_remove_max_segment
is initialized to SPA_MAXBLOCKSIZE.
Change zfs_condense_indirect_commit_entry_delay_ticks to
zfs_condense_indirect_commit_entry_delay_ms for consistency with
most other tunables in which delays are specified in ms.
* ZTS changes:
Use set_tunable rather than mdb
Use zpool sync as appropriate
Use sync_pool instead of sync
Kill jobs during test_removal_with_operation to allow unmount/export
Don't add non-disk names such as "mirror" or "raidz" to $DISKS
Use $TEST_BASE_DIR instead of /tmp
Increase HZ from 100 to 1000 which is more common on Linux
removal_multiple_indirection.ksh
Reduce iterations in order to not time out on the code
coverage builders.
removal_resume_export:
Functionally, the test case is correct but there exists a race
where the kernel thread hasn't been fully started yet and is
not visible. Wait for up to 1 second for the removal thread
to be started before giving up on it. Also, increase the
amount of data copied in order that the removal not finish
before the export has a chance to fail.
* MMP compatibility, the concept of concrete versus non-concrete devices
has slightly changed the semantics of vdev_writeable(). Update
mmp_random_leaf_impl() accordingly.
* Updated dbuf_remap() to handle the org.zfsonlinux:large_dnode pool
feature which is not supported by OpenZFS.
* Added support for new vdev removal tracepoints.
* Test cases removal_with_zdb and removal_condense_export have been
intentionally disabled. When run manually they pass as intended,
but when running in the automated test environment they produce
unreliable results on the latest Fedora release.
They may work better once the upstream pool import refectoring is
merged into ZoL at which point they will be re-enabled.
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Alex Reece <alex@delphix.com>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Richard Laager <rlaager@wiktel.com>
Reviewed by: Tim Chase <tim@chase2k.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Garrett D'Amore <garrett@damore.org>
Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>
OpenZFS-issue: https://www.illumos.org/issues/7614
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/f539f1ebCloses#6900
Currently, scrubs and resilvers can take an extremely
long time to complete. This is largely due to the fact
that zfs scans process pools in logical order, as
determined by each block's bookmark. This makes sense
from a simplicity perspective, but blocks in zfs are
often scattered randomly across disks, particularly
due to zfs's copy-on-write mechanisms.
This patch improves performance by splitting scrubs
and resilvers into a metadata scanning phase and an IO
issuing phase. The metadata scan reads through the
structure of the pool and gathers an in-memory queue
of I/Os, sorted by size and offset on disk. The issuing
phase will then issue the scrub I/Os as sequentially as
possible, greatly improving performance.
This patch also updates and cleans up some of the scan
code which has not been updated in several years.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Authored-by: Saso Kiselkov <saso.kiselkov@nexenta.com>
Authored-by: Alek Pinchuk <apinchuk@datto.com>
Authored-by: Tom Caputi <tcaputi@datto.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#3625Closes#6256
With PR 5756 the zfs module now supports c99 and the
remaining past c89 workarounds can be undone.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Don Brady <don.brady@delphix.com>
Closes#6816
This patch resolves a minor issue where an ASSERT in
metaslab_passivate() that only applies to non weight-based
metaslabs was erroneously applied to all metaslabs.
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Authored by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Saso Kiselkov <saso.kiselkov@nexenta.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>
We don't want to dirty any data when we're in the final txgs of the pool
export logic. This change introduces checks to make sure that no data is
dirtied after a certain point. It also addresses the culprit of this
specific bug – the space map cannot be upgraded when we're in final
stages of pool export. If we encounter a space map that wants to be
upgraded in this phase, then we simply ignore the request as it will get
retried the next time we set the fragmentation metric on that metaslab.
OpenZFS-issue: https://www.illumos.org/issues/8023
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/2ef00f5Closes#5991
Authored by: George Wilson <george.wilson@delphix.com>
Reviewed by: Igor Kozhukhov <ikozhukhov@gmail.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: George Melikov <mail@gmelikov.ru>
OpenZFS-issue: https://www.illumos.org/issues/7072
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/c39a2aaCloses#5694
Porting notes:
- vdev.c: 'vdev_get_stats' changes are moved to 'vdev_get_stats_ex'.
- vdev_disk.c: ignored, Linux specific code is different.
metaslab_t:ms_freetree[TXG_SIZE] is only used in syncing context. We
should replace it with two trees: the freeing tree (ranges that we are
freeing this syncing txg) and the freed tree (ranges which have been
freed this txg).
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Tim Chase <tim@chase2k.com>
OpenZFS-issue: https://www.illumos.org/issues/7613
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/a8698da2Closes#5598
This change introduces a new weighting algorithm to improve
metaslab selection. The new weighting algorithm relies on the
SPACEMAP_HISTOGRAM feature. As a result, the metaslab weight
now encodes the type of weighting algorithm used (size-based
vs segment-based).
Porting Notes: The metaslab allocation tracing code is conditionally
removed on linux (dependent on mdb debugger).
Authored by: George Wilson <george.wilson@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Chris Siden <christopher.siden@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Pavel Zakharov pavel.zakharov@delphix.com
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Don Brady <don.brady@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Don Brady <don.brady@intel.com>
OpenZFS-issue: https://www.illumos.org/issues/7303
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/d5190931bdCloses#5404
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Haakan T Johansson <f96hajo@chalmers.se>
Closes#5547Closes#5543
Enable picky cstyle checks and resolve the new warnings. The vast
majority of the changes needed were to handle minor issues with
whitespace formatting. This patch contains no functional changes.
Non-whitespace changes are as follows:
* 8 times ; to { } in for/while loop
* fix missing ; in cmd/zed/agents/zfs_diagnosis.c
* comment (confim -> confirm)
* change endline , to ; in cmd/zpool/zpool_main.c
* a number of /* BEGIN CSTYLED */ /* END CSTYLED */ blocks
* /* CSTYLED */ markers
* change == 0 to !
* ulong to unsigned long in module/zfs/dsl_scan.c
* rearrangement of module_param lines in module/zfs/metaslab.c
* add { } block around statement after for_each_online_node
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Reviewed-by: Håkan Johansson <f96hajo@chalmers.se>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#5465
Add the TASKQID_INVALID macros and update callers to use the macro
instead of testing against 0. There is no functional change
even though the functions in zfs_ctldir.c incorrectly used -1
instead of 0.
Reviewed-by: Tom Caputi <tcaputi@datto.com>
Reviewed-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #5347
OpenZFS 7090 - zfs should throttle allocations
Authored by: George Wilson <george.wilson@delphix.com>
Reviewed by: Alex Reece <alex@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Sebastien Roy <sebastien.roy@delphix.com>
Approved by: Matthew Ahrens <mahrens@delphix.com>
Ported-by: Don Brady <don.brady@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
When write I/Os are issued, they are issued in block order but the ZIO
pipeline will drive them asynchronously through the allocation stage
which can result in blocks being allocated out-of-order. It would be
nice to preserve as much of the logical order as possible.
In addition, the allocations are equally scattered across all top-level
VDEVs but not all top-level VDEVs are created equally. The pipeline
should be able to detect devices that are more capable of handling
allocations and should allocate more blocks to those devices. This
allows for dynamic allocation distribution when devices are imbalanced
as fuller devices will tend to be slower than empty devices.
The change includes a new pool-wide allocation queue which would
throttle and order allocations in the ZIO pipeline. The queue would be
ordered by issued time and offset and would provide an initial amount of
allocation of work to each top-level vdev. The allocation logic utilizes
a reservation system to reserve allocations that will be performed by
the allocator. Once an allocation is successfully completed it's
scheduled on a given top-level vdev. Each top-level vdev maintains a
maximum number of allocations that it can handle (mg_alloc_queue_depth).
The pool-wide reserved allocations (top-levels * mg_alloc_queue_depth)
are distributed across the top-level vdevs metaslab groups and round
robin across all eligible metaslab groups to distribute the work. As
top-levels complete their work, they receive additional work from the
pool-wide allocation queue until the allocation queue is emptied.
OpenZFS-issue: https://www.illumos.org/issues/7090
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/4756c3d7Closes#5258
Porting Notes:
- Maintained minimal stack in zio_done
- Preserve linux-specific io sizes in zio_write_compress
- Added module params and documentation
- Updated to use optimize AVL cmp macros
perf: 2.75x faster ddt_entry_compare()
First 256bits of ddt_key_t is a block checksum, which are expected
to be close to random data. Hence, on average, comparison only needs to
look at first few bytes of the keys. To reduce number of conditional
jump instructions, the result is computed as: sign(memcmp(k1, k2)).
Sign of an integer 'a' can be obtained as: `(0 < a) - (a < 0)` := {-1, 0, 1} ,
which is computed efficiently. Synthetic performance evaluation of
original and new algorithm over 1G random keys on 2.6GHz Intel(R) Xeon(R)
CPU E5-2660 v3:
old 6.85789 s
new 2.49089 s
perf: 2.8x faster vdev_queue_offset_compare() and vdev_queue_timestamp_compare()
Compute the result directly instead of using conditionals
perf: zfs_range_compare()
Speedup between 1.1x - 2.5x, depending on compiler version and
optimization level.
perf: spa_error_entry_compare()
`bcmp()` is not suitable for comparator use. Use `memcmp()` instead.
perf: 2.8x faster metaslab_compare() and metaslab_rangesize_compare()
perf: 2.8x faster zil_bp_compare()
perf: 2.8x faster mze_compare()
perf: faster dbuf_compare()
perf: faster compares in spa_misc
perf: 2.8x faster layout_hash_compare()
perf: 2.8x faster space_reftree_compare()
perf: libzfs: faster avl tree comparators
perf: guid_compare()
perf: dsl_deadlist_compare()
perf: perm_set_compare()
perf: 2x faster range_tree_seg_compare()
perf: faster unique_compare()
perf: faster vdev_cache _compare()
perf: faster vdev_uberblock_compare()
perf: faster fuid _compare()
perf: faster zfs_znode_hold_compare()
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Signed-off-by: Richard Elling <richard.elling@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#5033
As of gcc 6.1.1 20160621 (Red Hat 6.1.1-3) a self-comparison is
detected by gcc in metaslab_alloc(). Resolve the warning by passing
a physical size of 0 to BP_SET_BIRTH() as it done by other callers.
module/zfs/metaslab.c: In function ‘metaslab_alloc’:
module/zfs/metaslab.c:2575:184: error: self-comparison always evaluates
to true [-Werror=tautological-compare]
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Gvozden Neskovic <neskovic@gmail.com>
Issue #4907
When debugging is enabled on a very recent version of gcc
(tested with 5.3.0), DVA_SET_GANG(dva, !!(flags)) fails
because an assertion causes a comparison between what is
technically a boolean and an integer.
Signed-off-by: DHE <git@dehacked.net>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#4465
The fast write mutex is intended to protect accounting, but it is
redundant because all accounting is performed through atomic operations.
It also serializes all metaslab IO behind a mutex, which introduces a
theoretical scaling regression that the Illumos developers did not like
when we showed this to them. Removing it makes the selection of the
metaslab_group lock free as it is on Illumos. The selection is not quite
the same without the lock because the loop races with IO completions,
but any imbalances caused by this are likely to be corrected by
subsequent metaslab group selections.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3643
The LBA weighting makes sense on rotational media where the outer tracks
have twice the bandwidth of the inner tracks. However, it is detrimental
on nonrotational media such as solid state disks, where the only effect
is to ensure that metaslabs enter the best-fit allocation behavior
sooner, which is detrimental to performance. It also makes no sense on
files where the underlying filesystem can arrange things however it
wants.
Signed-off-by: Richard Yao <ryao@gentoo.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3712
Under Linux filesystem threads responsible for handling I/O are
normally created with the maximum priority. Non-I/O filesystem
processes run with the default priority. ZFS should adopt the
same priority scheme under Linux to maintain good performance
and so that it will complete fairly when other Linux filesystems
are active. The priorities have been updated to the following:
$ ps -eLo rtprio,cls,pid,pri,nice,cmd | egrep 'z_|spl_|zvol|arc|dbu|meta'
- TS 10743 19 -20 [spl_kmem_cache]
- TS 10744 19 -20 [spl_system_task]
- TS 10745 19 -20 [spl_dynamic_tas]
- TS 10764 19 0 [dbu_evict]
- TS 10765 19 0 [arc_prune]
- TS 10766 19 0 [arc_reclaim]
- TS 10767 19 0 [arc_user_evicts]
- TS 10768 19 0 [l2arc_feed]
- TS 10769 39 0 [z_unmount]
- TS 10770 39 -20 [zvol]
- TS 11011 39 -20 [z_null_iss]
- TS 11012 39 -20 [z_null_int]
- TS 11013 39 -20 [z_rd_iss]
- TS 11014 39 -20 [z_rd_int_0]
- TS 11022 38 -19 [z_wr_iss]
- TS 11023 39 -20 [z_wr_iss_h]
- TS 11024 39 -20 [z_wr_int_0]
- TS 11032 39 -20 [z_wr_int_h]
- TS 11033 39 -20 [z_fr_iss_0]
- TS 11041 39 -20 [z_fr_int]
- TS 11042 39 -20 [z_cl_iss]
- TS 11043 39 -20 [z_cl_int]
- TS 11044 39 -20 [z_ioctl_iss]
- TS 11045 39 -20 [z_ioctl_int]
- TS 11046 39 -20 [metaslab_group_]
- TS 11050 19 0 [z_iput]
- TS 11121 38 -19 [z_wr_iss]
Note that under Linux the meaning of a processes priority is inverted
with respect to illumos. High values on Linux indicate a _low_ priority
while high value on illumos indicate a _high_ priority.
In order to preserve the logical meaning of the minclsyspri and
maxclsyspri macros when they are used by the illumos wrapper functions
their values have been inverted. This way when changes are merged
from upstream illumos we won't need to remember to invert the macro.
It could also lead to confusion.
This patch depends on https://github.com/zfsonlinux/spl/pull/466.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes#3607
Reclaim during metaslab preloading can cause deadlocks involving znode
z_lock and ARC buffer header ht_lock.
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3532.
Over the years the default values for the taskqs used on Linux have
differed slightly from illumos. In the vast majority of cases this
was done to avoid creating an obnoxious number of idle threads which
would pollute the process listing.
With the addition of support for dynamic taskqs all multi-threaded
queues should be created as dynamic taskqs. This allows us to get
the best of both worlds.
* The illumos default values for the I/O pipeline can be restored.
These values are known to work well for most workloads. The only
exception is the zio write interrupt taskq which is changed to
ZTI_P(12, 8). At least under Linux more threads has been shown
to improve performance, see commit 7e55f4e.
* Reduces the number of idle threads on the system when it's not
under heavy load. The maximum number of threads will only be
created when they are required.
* Remove the vdev_file_taskq and rely on the system_taskq instead
which is now dynamic and may have up to 64-threads. Again this
brings us back inline with upstream.
* Tasks dispatched with taskq_dispatch_ent() are allowed to use
dynamic taskqs. The Linux taskq implementation supports this.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tim Chase <tim@chase2k.com>
Closes#3507
This seems generally useful. metaslab_aliquot is the ZFS allocation
granularity, which is roughly equivalent to what is called the stripe
size in traditional RAID arrays. It seems relevant to performance
tuning.
Signed-off-by: Etienne Dechamps <etienne@edechamps.fr>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The metaslab allocator device selection algorithm contains a bias
mechanism whose goal is to achieve roughly equal disk space usage across
all top-level vdevs.
It seems that the initial rationale for this code was to allow newly
added (empty) vdevs to "come up to speed" faster in an attempt to make
the pool quickly converge to a steady state where all vdevs are equally
utilized.
While the code seems to work reasonably well for this use case, there
is another scenario in which this algorithm fails miserably: the case
where top-level vdevs don't have the same sizes (capacities). ZFS
allows this, and it is a good feature to have, so that users who simply
want to build a pool with the disks they happen to have lying around can
do so even if the disks have heteregenous sizes.
Here's a script that simulates a pool with two vdevs, with one 4X larger
than the other:
dd if=/dev/zero of=/tmp/d1 bs=1 count=1 seek=134217728
dd if=/dev/zero of=/tmp/d2 bs=1 count=1 seek=536870912
zpool create testspace /tmp/d1 /tmp/d2
dd if=/dev/zero of=/testspace/foobar bs=1M count=256
zpool iostat -v testspace
Before this commit, the script would output the following:
capacity
pool alloc free
---------- ----- -----
testspace 252M 375M
/tmp/d1 104M 18.5M
/tmp/d2 148M 356M
---------- ----- -----
This demonstrates that the current code handles this situation very
poorly: d1 shows 85% usage despite the pool itself being only 40% full.
d1 is quite saturated at this point, and is slowing down the entire pool
due to saturation, fragmentation and the like.
In contrast, here's the result with the code in this commit:
capacity
pool alloc free
---------- ----- -----
testspace 252M 375M
/tmp/d1 56.7M 66.3M
/tmp/d2 195M 309M
---------- ----- ------
This looks much better. d1 is 46% used, which is close to the overall
pool utilization (40%). The code still doesn't result in perfectly
balanced allocation, probably because of the way mg_bias is applied
which does not guarantee perfect accuracy, but this is still much better
than before.
Signed-off-by: Etienne Dechamps <etienne@edechamps.fr>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3389
Replace taskq_wait() with taskq_wait_oustanding(). This way callers
will only block until previously submitted tasks have been completed.
This was the previous behavior of task_wait() prior to the introduction
of taskq_wait_outstanding() so this isn't really a functionalty change
for these callers.
Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
The metaslab_min_alloc_size option is no longer used in the code.
This functionality was removed by commit f3a7f66 and the module
options should have been dropped at that time.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
When a bad DVA is encountered in metaslab_free_dva() the system
should treat it as fatal. This indicates that somehow a damaged
DVA was written to disk and that should be impossible.
However, we have seen a handful of reports over the years of pools
somehow being damaged in this way. Since this damage can render
otherwise intact pools unimportable, and the consequence of skipping
the bad DVA is only leaked free space, it makes sense to provide
a mechanism to ignore the bad DVA. Setting the zfs_recover=1 module
option will cause the DVA to be ignored which may allow the pool to
be imported.
Since zfs_recover=0 by default any pool attempting to free a bad DVA
will treat it as a fatal error preserving the current behavior.
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3099
Issue #3090
Issue #2720
