* Illumos zfs issue #3035 [1] LZ4 compression support in ZFS.
LZ4 is a new high-speed BSD-licensed compression algorithm created
by Yann Collet that delivers very high compression and decompression
performance compared to lzjb (>50% faster on compression, >80% faster
on decompression and around 3x faster on compression of incompressible
data), while giving better compression ratio [1].
This version of LZ4 corresponds to upstream's [2] revision 85.
Please note that for obvious reasons this is not backward read
compatible. This means once a pool have LZ4 compressed data, these
data can no longer be read by older ZFS implementations.
Local changes:
- On-stack hash table disabled and using kernel slab allocator
instead, at this time. This requires larger kernel thread stack
for zio workers. This may change in the future should we adjusted
the zio workers' thread stack size.
- likely and unlikely will be undefined if they are already defined,
this is required for i386 XEN build.
- Removed De Bruijn sequence based __builtin_ctz family of builtins
in favor of the latter. Both GCC and clang supports these builtins.
- Changed the way the LZ4 code detects endianness.
- Manual pages modifications to mention the feature based on Illumos
counterpart.
- Boot loader changes to make it support LZ4 decompression.
[1] https://www.illumos.org/issues/3035
[2] http://code.google.com/p/lz4/source/list
Obtained from: Illumos (13921:9d721847e469)
Tested on: FreeBSD/amd64
MFC after: 1 month
Few new things available from now on:
- Data deduplication.
- Triple parity RAIDZ (RAIDZ3).
- zfs diff.
- zpool split.
- Snapshot holds.
- zpool import -F. Allows to rewind corrupted pool to earlier
transaction group.
- Possibility to import pool in read-only mode.
MFC after: 1 month
- better ACL caching and speedup of ACL permission checks
- faster handling of stat()
- lowered mutex contention in the read/writer lock (rrwlock)
- several related bugfixes
Detailed information (OpenSolaris onnv changesets and Bug IDs):
9749:105f407a2680
6802734 Support for Access Based Enumeration (not used on FreeBSD)
6844861 inconsistent xattr readdir behavior with too-small buffer
9866:ddc5f1d8eb4e
6848431 zfs with rstchown=0 or file_chown_self privilege allows user to "take" ownership
9981:b4907297e740
6775100 stat() performance on files on zfs should be improved
6827779 rrwlock is overly protective of its counters
10143:d2d432dfe597
6857433 memory leaks found at: zfs_acl_alloc/zfs_acl_node_alloc
6860318 truncate() on zfsroot succeeds when file has a component of its path set without access permission
10232:f37b85f7e03e
6865875 zfs sometimes incorrectly giving search access to a dir
10250:b179ceb34b62
6867395 zpool_upgrade_007_pos testcase panic'd with BAD TRAP: type=e (#pf Page fault)
10269:2788675568fd
6868276 zfs_rezget() can be hazardous when znode has a cached ACL
10295:f7a18a1e9610
6870564 panic in zfs_getsecattr
Approved by: delphij (mentor)
Obtained from: OpenSolaris (multiple Bug IDs)
MFC after: 2 weeks
This bring huge amount of changes, I'll enumerate only user-visible changes:
- Delegated Administration
Allows regular users to perform ZFS operations, like file system
creation, snapshot creation, etc.
- L2ARC
Level 2 cache for ZFS - allows to use additional disks for cache.
Huge performance improvements mostly for random read of mostly
static content.
- slog
Allow to use additional disks for ZFS Intent Log to speed up
operations like fsync(2).
- vfs.zfs.super_owner
Allows regular users to perform privileged operations on files stored
on ZFS file systems owned by him. Very careful with this one.
- chflags(2)
Not all the flags are supported. This still needs work.
- ZFSBoot
Support to boot off of ZFS pool. Not finished, AFAIK.
Submitted by: dfr
- Snapshot properties
- New failure modes
Before if write requested failed, system paniced. Now one
can select from one of three failure modes:
- panic - panic on write error
- wait - wait for disk to reappear
- continue - serve read requests if possible, block write requests
- Refquota, refreservation properties
Just quota and reservation properties, but don't count space consumed
by children file systems, clones and snapshots.
- Sparse volumes
ZVOLs that don't reserve space in the pool.
- External attributes
Compatible with extattr(2).
- NFSv4-ACLs
Not sure about the status, might not be complete yet.
Submitted by: trasz
- Creation-time properties
- Regression tests for zpool(8) command.
Obtained from: OpenSolaris
ZFS file system was ported from OpenSolaris operating system. The code in under
CDDL license.
I'd like to thank all SUN developers that created this great piece of software.
Supported by: Wheel LTD (http://www.wheel.pl/)
Supported by: The FreeBSD Foundation (http://www.freebsdfoundation.org/)
Supported by: Sentex (http://www.sentex.net/)
