Detect a slow raidz child during reads

A single slow responding disk can affect the overall read
performance of a raidz group.  When a raidz child disk is
determined to be a persistent slow outlier, then have it
sit out during reads for a period of time. The raidz group
can use parity to reconstruct the data that was skipped.

Each time a slow disk is placed into a sit out period, its
`vdev_stat.vs_slow_ios count` is incremented and a zevent
class `ereport.fs.zfs.delay` is posted.

The length of the sit out period can be changed using the
`raid_read_sit_out_secs` module parameter.  Setting it to
zero disables slow outlier detection.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <paul.dagnelie@klarasystems.com>
Contributions-by: Don Brady <don.brady@klarasystems.com>
Contributions-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #17227
This commit is contained in:
Paul Dagnelie
2025-08-27 16:41:48 -07:00
committed by Brian Behlendorf
parent 0620c979a5
commit d64711c202
28 changed files with 1399 additions and 13 deletions
+10
View File
@@ -190,6 +190,16 @@ Issued when a scrub is resumed on a pool.
.It Sy scrub.paused
Issued when a scrub is paused on a pool.
.It Sy bootfs.vdev.attach
.It Sy sitout
Issued when a
.Sy RAIDZ
or
.Sy DRAID
vdev triggers the
.Sy autosit
logic.
This logic detects when a disk in such a vdev is significantly slower than its
peers, and sits them out temporarily to preserve the performance of the pool.
.El
.
.Sh PAYLOADS