we're having a weird disk I/O problem on a 5.4 server connected to an external
SAS storage with an LSI logic megaraid sas 1078.
The server is used as a samba file server.
Every time we try to copy some large file to the storage-based file system, the
disk utilization see-saws up to 100% to several seconds of inactivity, to climb
up again to 100% and so forth.
Here are a snip from the iostat -kx 1:
Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz
await svctm %util
sdb1 0.00 133811.00 0.00 1889.00 0.00 513660.00 543.84
126.24 65.00 0.47 89.40
sdb1 0.00 138.61 0.00 109.90 0.00 29845.54 543.14
2.54 54.32 0.37 4.06
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
sdb1 0.00 134680.00 0.00 1920.00 0.00 526524.00 548.46
126.06 64.57 0.47 90.00
sdb1 0.00 142.00 0.00 74.00 0.00 20740.00 560.54 1.25
45.14 0.47 3.50
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
sdb1 0.00 0.00 1.00 0.00 4.00 0.00 8.00 0.01
14.00 14.00 1.40
sdb1 0.00 116129.00 1.00 1576.00 4.00 434816.00 551.45
125.47 75.38 0.57 90.30
sdb1 0.00 17301.98 0.00 412.87 0.00 106506.93 515.93
24.59 75.40 0.48 19.80
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
sdb1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00
It happens when I copy a file over the net using samba or when copying/creating
a local file
It looks like the disk tries to get more than it can handle, then it chokes
with data and stales for a few seconds until some buffer empties and it's able
to get a bit more data again.
It happens in two identical servers, so I'd discard faulty hardware as the
cause and look into a miscofiguration issue.
Are there any guidelines/docs for heavy I/O tuning? are there any issues with
this raid controller?
any help will be apreciated
Fer
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