Date: Tue, 22 Sep 2015 20:38:25 +0300 From: Dmitrijs <war@dim.lv> To: freebsd-questions@freebsd.org Subject: zfs performance degradation Message-ID: <56019211.2050307@dim.lv>
next in thread | raw e-mail | index | archive | help
Goog afternoon,
I've encountered strange ZFS behavior - serious performance
degradation over few days. Right after setup on fresh ZFS (2 hdd in a
mirror) I made a test on a file 30Gb size with dd like
dd if=test.mkv of=/dev/null bs=64k
and got 150+Mbs speed.
Today I got only 90Mbs, tested with different blocksizes, many times,
speed seems to be stable +-5%
nas4free: divx# dd if=test.mkv of=/dev/null bs=64k
484486+1 records in
484486+1 records out
31751303111 bytes transferred in 349.423294 secs (90867734 bytes/sec)
Computer\system details:
nas4free: /mnt# uname -a
FreeBSD nas4free.local 10.2-RELEASE-p2 FreeBSD 10.2-RELEASE-p2 #0
r287260M: Fri Aug 28 18:38:18 CEST 2015
root@dev.nas4free.org:/usr/obj/nas4free/usr/src/sys/NAS4FREE-amd64 amd64
RAM 4Gb
I've got brand new 2x HGST HDN724040ALE640, 4Тб, 7200rpm (ada0, ada1)
for pool data4.
Another pool, data2, performs slightly better even on older\cheaper WD
Green 5400 HDDs, up to 99Mbs.
nas4free: /mnt# zpool status
pool: data2
state: ONLINE
scan: none requested
config:
NAME STATE READ WRITE CKSUM
data2 ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ada2 ONLINE 0 0 0
ada3 ONLINE 0 0 0
errors: No known data errors
pool: data4
state: ONLINE
scan: none requested
config:
NAME STATE READ WRITE CKSUM
data4 ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ada0 ONLINE 0 0 0
ada1 ONLINE 0 0 0
errors: No known data errors
While dd is running, gstat is showing like:
dT: 1.002s w: 1.000s
L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name
0 366 366 46648 1.1 0 0 0.0 39.6| ada0
1 432 432 54841 1.0 0 0 0.0 45.1| ada1
so iops are very high, while %busy is quite low. It averages about 50%,
rare peaks till 85-90%
Even top shows no significant load:
last pid: 61983; load averages: 0.44, 0.34, 0.37 up 11+07:51:31 16:44:56
40 processes: 1 running, 39 sleeping
CPU: 0.3% user, 0.0% nice, 6.4% system, 1.1% interrupt, 92.1% idle
Mem: 21M Active, 397M Inact, 2101M Wired, 56M Cache, 94M Buf, 1044M Free
ARC: 1024M Total, 232M MFU, 692M MRU, 160K Anon, 9201K Header, 91M Other
Swap: 4096M Total, 4096M Free
Not displaying idle processes.
PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND
61981 root 1 30 0 12364K 2084K zio->i 3 0:09 18.80% dd
61966 root 1 22 0 58392K 7144K select 3 0:24 3.86% proftpd
Zpool list:
nas4free: /mnt# zpool list
NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
data2 1.81T 578G 1.25T - 11% 31% 1.00x ONLINE -
data4 3.62T 2.85T 797G - 36% 78% 1.00x ONLINE -
Could it happen because of pool being 78% full? So I cannot fill puls full?
Can anyone please advice how could I fix the situation - or is it normal?
I've googled a lot about vmaxnodes, vminnodes but advices are mostly
controversial and doesn't help.
I can provide additional system output on request.
best regards,
Dmitry
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?56019211.2050307>