Paul Dagnelie df55ba7c49 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		2025-09-10 15:31:30 -07:00
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sys	Detect a slow raidz child during reads	2025-09-10 15:31:30 -07:00