CTL HA functionality was originally implemented by Copan many years ago,
but large part of the sources was never published. This change includes
clean room implementation of the missing code and fixes for many bugs.
This code supports dual-node HA with ALUA in four modes:
- Active/Unavailable without interlink between nodes;
- Active/Standby with second node handling only basic LUN discovery and
reservation, synchronizing with the first node through the interlink;
- Active/Active with both nodes processing commands and accessing the
backing storage, synchronizing with the first node through the interlink;
- Active/Active with second node working as proxy, transfering all
commands to the first node for execution through the interlink.
Unlike original Copan's implementation, depending on specific hardware,
this code uses simple custom TCP-based protocol for interlink. It has
no authentication, so it should never be enabled on public interfaces.
The code may still need some polishing, but generally it is functional.
Relnotes: yes
Sponsored by: iXsystems, Inc.
To avoid conflicts between target and initiator devices in CAM, make
CTL use target ID reported by HBA as its initiator_id in XPT_PATH_INQ.
That target ID is known to never be used for initiator role, so it won't
conflict. For Fibre Channel and FireWire HBAs this specific ID choice
is irrelevant since all target IDs there are virtual. Same time for SPI
HBAs it seems could be even requirement to use same target ID for both
initiator and target roles.
While there are some more things to polish in isp(4) driver, first tests
of using both roles same time on the same port appeared successfull:
# camcontrol devlist -v
scbus0 on isp0 bus 0:
<FREEBSD CTLDISK 0001> at scbus0 target 1 lun 0 (da20,pass21)
<> at scbus0 target 256 lun 0 (ctl0)
<> at scbus0 target -1 lun ffffffff (ctl1)
- remove last remnants of never implemented multiple targets support;
- implement missing support for LUN mapping in this area.
Due to existing locking constraints LUN mapping code is practically
unlocked at this point. Hopefully it is not racy enough to live until
somebody get idea how to call sleeping fronend methods under lock also
taken by the same frontend in non-sleepable context. :(
At this point CTL has no known use case for device queue freezes.
Same time existing (considered to be broken) code was found to cause
modify-after-free issues.
Discussed with: ken
MFC after: 1 week
If we aggregated status sending with data move and got error, allow status
to be updated and resent again separately. Without this command may stuck
without status sent at all.
MFC after: 2 weeks
Make CTL core and block backend set success status before initiating last
data move for read commands. Make CAM target and iSCSI frontends detect
such condition and send command status together with data. New I/O flag
allows to skip duplicate status sending on later fe_done() call.
For Fibre Channel this change saves one of three interrupts per read command,
increasing performance from 126K to 160K IOPS. For iSCSI this change saves
one of three PDUs per read command, increasing performance from 1M to 1.2M
IOPS.
MFC after: 1 month
Sponsored by: iXsystems, Inc.
Old allocator created significant lock congestion protecting its lists
of preallocated I/Os, while UMA provides much better SMP scalability.
The downside of UMA is lack of reliable preallocation, that could guarantee
successful allocation in non-sleepable environments. But careful code
review shown, that only CAM target frontend really has that requirement.
Fix that making that frontend preallocate and statically bind CTL I/O for
every ATIO/INOT it preallocates any way. That allows to avoid allocations
in hot I/O path. Other frontends either may sleep in allocation context
or can properly handle allocation errors.
On 40-core server with 6 ZVOL-backed LUNs and 7 iSCSI client connections
this change increases peak performance from ~700K to >1M IOPS! Yay! :)
MFC after: 1 month
Sponsored by: iXsystems, Inc.
In this mode one head is in Active state, supporting all commands, while
another is in Standby state, supporting only minimal LUN discovery subset.
It is still incomplete since Standby state requires reservation support,
which is impossible to do right without having interlink between heads.
But it allows to run some basic experiments.
Queued async events handling in CAM opened race, that may lead to duplicate
AC_PATH_REGISTERED events delivery during boot. That was not happening
before r272935 because the driver was initialized later. After that change
it started create duplicate ports in CTL.
Target mode operation does not depend on the initiator mode scan process.
This change allows the target driver to attach earlier and receive some
async events (like AC_CONTRACT) that could be lost otherwise.
MFC after: 1 week
This allows to clone VMs and move them between LUNs inside one storage
host without generating extra network traffic to the initiator and back,
and without being limited by network bandwidth.
LUNs participating in copy operation should have UNIQUE NAA or EUI IDs set.
For LUNs without these IDs VMWare will use traditional copy operations.
Beware: the above LUN IDs explicitly set to values non-unique from the VM
cluster point of view may cause data corruption if wrong LUN is addressed!
MFC after: 2 weeks
Sponsored by: iXsystems, Inc.
That should make operation more kind to multi-initiator environment.
Without this, other initiators may find out that something bad happened
to their commands only via command timeout.
If port passed negative IID value, the function will try to allocate IID
from the pool of unused, based on passed wwpn or name arguments. It does
all its best to make IID unique and persistent across reconnects.
This makes persistent reservation properly work for iSCSI. Previously,
in case of reconnects, reservation could be unexpectedly lost, or even
migrate between intiators.
Instead make ports provide wanted port and target IDs, and LUNs provide
wanted LUN IDs. After that core Device ID VPD code only had to link all
of them together and add relative port and port group numbers.
LUN ID for iSCSI LUNs no longer created by CTL, but by ctld, and passed
to CTL as "scsiname" LUN option. This makes LUNs to report the same set
of IDs, independently from the port through which it is accessed, as
required by SCSI specifications.
Before iSCSI implementation CTL had no knowledge about frontend drivers,
it had only frontends, which really were ports (alike to LUNs, if comparing
to backends). But iSCSI added there ioctl() method, which does not belong
to frontend as a port, but belongs to a frontend driver.
reduce lock congestion and improve SMP scalability of the SCSI/ATA stack,
preparing the ground for the coming next GEOM direct dispatch support.
Replace big per-SIM locks with bunch of smaller ones:
- per-LUN locks to protect device and peripheral drivers state;
- per-target locks to protect list of LUNs on target;
- per-bus locks to protect reference counting;
- per-send queue locks to protect queue of CCBs to be sent;
- per-done queue locks to protect queue of completed CCBs;
- remaining per-SIM locks now protect only HBA driver internals.
While holding LUN lock it is allowed (while not recommended for performance
reasons) to take SIM lock. The opposite acquisition order is forbidden.
All the other locks are leaf locks, that can be taken anywhere, but should
not be cascaded. Many functions, such as: xpt_action(), xpt_done(),
xpt_async(), xpt_create_path(), etc. are no longer require (but allow) SIM
lock to be held.
To keep compatibility and solve cases where SIM lock can't be dropped, all
xpt_async() calls in addition to xpt_done() calls are queued to completion
threads for async processing in clean environment without SIM lock held.
Instead of single CAM SWI thread, used for commands completion processing
before, use multiple (depending on number of CPUs) threads. Load balanced
between them using "hash" of the device B:T:L address.
HBA drivers that can drop SIM lock during completion processing and have
sufficient number of completion threads to efficiently scale to multiple
CPUs can use new function xpt_done_direct() to avoid extra context switch.
Make ahci(4) driver to use this mechanism depending on hardware setup.
Sponsored by: iXsystems, Inc.
MFC after: 2 months
r248917, r248918, r248978, r249001, r249014, r249030:
Remove multilevel freezing mechanism, implemented to handle specifics of
the ATA/SATA error recovery, when post-reset recovery commands should be
allocated when queues are already full of payload requests. Instead of
removing frozen CCBs with specified range of priorities from the queue
to provide free openings, use simple hack, allowing explicit CCBs over-
allocation for requests with priority higher (numerically lower) then
CAM_PRIORITY_OOB threshold.
Simplify CCB allocation logic by removing SIM-level allocation queue.
After that SIM-level queue manages only CCBs execution, while allocation
logic is localized within each single device.
Suggested by: gibbs
and kern.cam.ctl.disable tunable; those were introduced as a workaround
to make it possible to boot GENERIC on low memory machines.
With ctl(4) being built as a module and automatically loaded by ctladm(8),
this makes CTL work out of the box.
Reviewed by: ken
Sponsored by: FreeBSD Foundation
every architecture's busdma_machdep.c. It is done by unifying the
bus_dmamap_load_buffer() routines so that they may be called from MI
code. The MD busdma is then given a chance to do any final processing
in the complete() callback.
The cam changes unify the bus_dmamap_load* handling in cam drivers.
The arm and mips implementations are updated to track virtual
addresses for sync(). Previously this was done in a type specific
way. Now it is done in a generic way by recording the list of
virtuals in the map.
Submitted by: jeff (sponsored by EMC/Isilon)
Reviewed by: kan (previous version), scottl,
mjacob (isp(4), no objections for target mode changes)
Discussed with: ian (arm changes)
Tested by: marius (sparc64), mips (jmallet), isci(4) on x86 (jharris),
amd64 (Fabian Keil <freebsd-listen@fabiankeil.de>)
Previously CTL would leave individual LUNs enabled in the target
driver, whether or not the port as a whole was enabled. It would
also leave the wildcard LUN enabled indefinitely.
This change means that CTL will enable and disable any active LUNs,
as well as the wildcard LUN, when enabling and disabling a port.
Also, fix a bug that could crop up due to an uninitialized CCB
type.
ctl.c: Before calling ctl_frontend_online(), run through
the LUN list and enable all active LUNs.
After calling ctl_frontend_offline(), run through
the LUN list and disble all active LUNs.
scsi_ctl.c: Before bringing a port online, allocate the
wildcard peripheral for that bus. And after taking
a port offline, invalidate the wildcard peripheral
for that bus.
Make sure that we hold the SIM lock around all
calls to xpt_action() and other transport layer
interfaces that require it.
Use CAM_SIM_{LOCK|UNLOCK} consistently to acquire
and release the SIM lock.
Update a number of outdated comments. Some of
these should have been fixed long ago.
Actually do LUN disbables now. The newer drivers
in the tree work correctly for this as far as I
know.
Initialize the CCB type to CTLFE_CCB_DEFAULT to
avoid a panic due to uninitialized memory.
Submitted by: Chuck Tuffli (partially)
MFC after: 1 week
ctl_frontend_cam_sim.c: Coalesce cfcs_online() and cfcs_offline()
into a single function since these were
identical except for one line.
Make sure we hold the SIM lock around path
creation, and calling xpt_rescan().
scsi_ctl.c: In ctlfe_onoffline(), make sure we hold the
SIM lock around path creation and free
calls, as well as xpt_action().
In ctlfe_lun_enable(), hold the SIM lock
around path and peripheral operations that
require it.
Sponsored by: Spectra Logic Corporation
MFC after: 1 week
data pointer. This is a temp fix that resubmits the
command, adjusted, so that the backend can fetch the
data again.
Sponsored by: Spectralogic
MFC after: 1 month
to attach to target capable HBAs that implement the old immediate
notify (XPT_IMMED_NOTIFY) and notify acknowledge (XPT_NOTIFY_ACK)
CCBs. The new API has been in place since SVN change 196008 in
2009.
The solution is two-fold: fix CTL to handle the responses from the
HBAs, and convert the HBA drivers in question to use the new API.
These drivers have not been tested with CTL, so how well they will
interoperate with CTL is unknown.
scsi_target.c: Update the userland target example code to use the
new immediate notify API.
scsi_ctl.c: Detect when an immediate notify CCB is returned
with CAM_REQ_INVALID or CAM_PROVIDE_FAIL status,
and just free it.
Fix a duplicate assignment.
aic79xx.c,
aic79xx_osm.c: Update the aic79xx driver to use the new API.
Target mode is not enabled on for this driver, so
the changes will have no practical effect.
aic7xxx.c,
aic7xxx_osm.c: Update the aic7xxx driver to use the new API.
sbp_targ.c: Update the firewire target code to work with the
new API.
mpt_cam.c: Update the mpt(4) driver to work with the new API.
Target mode is only enabled for Fibre Channel
mpt(4) devices.
MFC after: 3 days
figure out domain, etc..
Zero ATIO and INOTify allocations. It makes for much
less guesswork when looking at the structure and
seeing 'deadc0de' present.
Reviewed by: kdm
MFC after: 2 weeks
Sponsored by: Spectralogic
