Il 2023-04-09 14:21 Arvid Picciani ha scritto:
Hi,
doing some performance tests i noticed that lvmraid + integrity +
thinpool outperforms zfs z1 by 5x while offering the same features.
(snapshots, integrity)
Is this somehow unsafe or how come it is so unpopular?
lvcreate --type raid1 --mirrors 1 --size '100M' loop --name loopmeta
--raidintegritymode journal
lvcreate --type raid1 --mirrors 1 --size '700M' loop --name loopdata
--raidintegritymode journal
lvconvert --type thin-pool --poolmetadata loop/loopmeta loop/loop
I benchmarked this setup quite heavily some years ago (when RHEL 8 was
shiny new), using integritysetup because lvm integration was not
available.
Be aware that in journal mode all random writes are sequentially
accumulated in the journal and are later destaged. If using HDDs this
last part can block your array for extended time. For example, using
fio, I noticed 50k random writes for 2s followed by 30s where random
iops was 0 (zero). Bitmap mode (rather than journal) was better
speed-wise, but be sure to understand the tradeoff.
Other notes regarding ZFS:
- ZRAID1 is the equivalent of RAID5 and has lower performance than
mirrors;
- recordsize plays an important role, but can affect benchmark results
in a non-intuitive manner;
- ZFS is heavily dependent on ARC - don't try to outsmart it with
syntethical tests, rather benchmark it your real workload.
Regards.
--
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.da...@assyoma.it - i...@assyoma.it
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