[LU-16493] recovery-small/144b fails with ZFS Created: 19/Jan/23  Updated: 14/Feb/23  Resolved: 14/Feb/23

Status: Resolved
Project: Lustre
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Bug Priority: Trivial
Reporter: Alex Zhuravlev Assignee: Alex Zhuravlev
Resolution: Fixed Votes: 0
Labels: None

Severity: 3
Rank (Obsolete): 9223372036854775807

 Description   

the subtest expects 50 files each with 1K stripes can be created in 60 seconds which is not quite enough for ZFS. I did local measurements and observed:

  • OST object precreation doesn't block creations (MDS has enough objects at any moment)
  • MDS needs to update last_used file for each OST object used, i.e. 50*1000=50K times
  • ZFS's writerecord and writerecord's declaration is still much slower compared to ldiskfs (2-3x slower)

 Comments   
Comment by Gerrit Updater [ 19/Jan/23 ]

"Alex Zhuravlev <bzzz@whamcloud.com>" uploaded a new patch: https://review.whamcloud.com/c/fs/lustre-release/+/49693
Subject: LU-16493 tests: recovery-small/144b to wait longer
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: ead9f854705427793091837945e7576ff79b96a2

Comment by Alex Zhuravlev [ 19/Jan/23 ]

did few measurements with LU-13139:

                                ldiskfs     zfs-op    zfs-noop
osd decl write        1              2             274
osd write		44		55          127
lod declare create	108577.  139043  396156
lod create		57952.    90884   171936

cost of DTAPI calls in usec, where zfs-op is master + LU-13132 + LU-14918, zfs-noop is clean master.
for each stripe OSP will be calling osd_declare_write() and osd_write(), this leads to much more expensive lod's declaration and creation.

Comment by Gerrit Updater [ 14/Feb/23 ]

"Oleg Drokin <green@whamcloud.com>" merged in patch https://review.whamcloud.com/c/fs/lustre-release/+/49693/
Subject: LU-16493 tests: recovery-small/144b to wait longer
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 1c8b40d5e445fac4b4809e082f622efb642e3da5

Comment by Peter Jones [ 14/Feb/23 ]

Landed for 2.16

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