c/mirror_zfs
1
0
Fork 0
mirror of https://git.proxmox.com/git/mirror_zfs.git synced 2026-05-30 02:34:14 +03:00
Code Issues Packages Projects Releases Wiki Activity

Persistent L2ARC

Browse Source 
This commit makes the L2ARC persistent across reboots. We implement
a light-weight persistent L2ARC metadata structure that allows L2ARC
contents to be recovered after a reboot. This significantly eases the
impact a reboot has on read performance on systems with large caches.

Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: George Wilson <gwilson@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Saso Kiselkov <skiselkov@gmail.com>
Co-authored-by: Jorgen Lundman <lundman@lundman.net>
Co-authored-by: George Amanakis <gamanakis@gmail.com>
Ported-by: Yuxuan Shui <yshuiv7@gmail.com>
Signed-off-by: George Amanakis <gamanakis@gmail.com>
Closes #925 
Closes #1823 
Closes #2672 
Closes #3744 
Closes #9582
This commit is contained in:
George Amanakis
2020-04-10 13:33:35 -04:00
committed by GitHub
parent 36a6e2335c
commit 77f6826b83
30 changed files with 3020 additions and 88 deletions
Download Patch File Download Diff File Expand all files Collapse all files
man/man8/zpoolconcepts.8
+22 -2
View File
@@ -323,8 +323,28 @@ If a read error is encountered on a cache device, that read I/O is reissued to
the original storage pool device, which might be part of a mirrored or raidz
configuration.
.Pp
The content of the cache devices is considered volatile, as is the case with
other system caches.
The content of the cache devices is persistent across reboots and restored
asynchronously when importing the pool in L2ARC (persistent L2ARC).
This can be disabled by setting
.Sy l2arc_rebuild_enabled = 0 .
For cache devices smaller than 1GB we do not write the metadata structures
required for rebuilding the L2ARC in order not to waste space. This can be
changed with
.Sy l2arc_rebuild_blocks_min_l2size .
The cache device header (512 bytes) is updated even if no metadata structures
are written. Setting
.Sy l2arc_headroom = 0
will result in scanning the full-length ARC lists for cacheable content to be
written in L2ARC (persistent ARC). If a cache device is added with
.Nm zpool Cm add
its label and header will be overwritten and its contents are not going to be
restored in L2ARC, even if the device was previously part of the pool. If a
cache device is onlined with
.Nm zpool Cm online
its contents will be restored in L2ARC. This is useful in case of memory pressure
where the contents of the cache device are not fully restored in L2ARC.
The user can off/online the cache device when there is less memory pressure
in order to fully restore its contents to L2ARC.
.Ss Pool checkpoint
Before starting critical procedures that include destructive actions (e.g
.Nm zfs Cm destroy