Detect a slow raidz child during reads #17227
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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. Signed-off-by: Don Brady <[email protected]>
also added test from Tony Signed-off-by: Don Brady <[email protected]>
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Because there will be a little bouncing between two PRs, and because there's two different authors involved, I'll be pushing fixup commits to this branch. Once everyone is happy with review, I will squash them down for merge. I'll close out the remaining review comments on #16900, and would like it if new comments could be added here. Thanks all for your patience; I know its a bit fiddly (it'd be nicer if Github would allow a PR to change branches, alas). |
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also changed 'raidz_read_sit_out_secs' to 'vdev_read_sit_out_secs' Signed-off-by: Don Brady <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
Review feedback. Signed-off-by: Rob Norris <[email protected]>
Signed-off-by: Rob Norris <[email protected]>
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Motivation and Context
Replacing #16900, which was almost finished with review updates but has stalled. I've been asked to take it over.
See original PR for details.
Types of changes
Checklist:
Signed-off-by.