[CentOS] waiting IOs...
John Doe
jdmls at yahoo.com
Thu Sep 10 15:44:52 UTC 2009
# iostat -m -x 10
Linux 2.6.18-8.1.6.el5 (data1.iol) 09/10/2009
. . .
avg-cpu: %user %nice %system %iowait %steal %idle
0.20 0.00 0.31 8.79 0.00 90.70
Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
cciss/c0d0 0.00 0.20 0.92 0.51 0.00 0.00 10.29 0.04 25.29 25.93 3.71
cciss/c0d1 0.00 0.20 3.68 2.45 0.02 0.01 11.07 0.06 9.87 7.27 4.45
cciss/c0d2 0.00 0.20 0.41 2.76 0.00 0.01 8.52 0.03 9.97 2.81 0.89
cciss/c0d3 1.23 0.51 3.98 1.53 0.03 0.01 14.52 0.05 9.69 8.07 4.45
cciss/c0d4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
cciss/c0d5 0.00 0.00 1.02 0.10 0.00 0.00 8.00 0.01 9.36 9.36 1.05
cciss/c0d6 2.45 0.20 0.92 0.51 0.06 0.00 87.43 0.01 9.64 7.21 1.03
cciss/c0d7 0.00 0.00 0.31 0.10 0.00 0.00 8.00 0.01 14.25 14.25 0.58
cciss/c0d8 0.00 0.00 0.10 1.84 0.00 0.01 8.00 0.01 7.26 1.42 0.28
cciss/c0d9 0.00 0.10 0.41 3.78 0.00 0.02 9.56 0.05 12.24 1.59 0.66
cciss/c1d0 0.00 6.03 0.00 1.74 0.00 0.02 26.94 0.04 25.35 12.59 2.19
avg-cpu: %user %nice %system %iowait %steal %idle
0.05 0.00 0.36 25.77 0.00 73.82
Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
cciss/c0d0 0.00 0.82 4.60 0.20 0.03 0.00 13.11 0.06 13.55 13.00 6.25
cciss/c0d1 1.23 1.43 1.94 0.20 0.02 0.01 29.33 0.02 11.48 11.48 2.46
cciss/c0d2 0.00 0.00 0.82 0.00 0.00 0.00 8.00 0.01 14.00 14.00 1.15
cciss/c0d3 2.45 1.43 11.25 0.20 0.07 0.01 14.43 0.12 10.62 10.52 12.04
cciss/c0d4 0.00 1.64 7.98 0.20 0.03 0.01 10.00 0.08 9.24 9.10 7.44
cciss/c0d5 5.93 0.20 22.09 0.20 2.19 0.00 201.03 0.58 26.06 1.88 4.19
cciss/c0d6 2.45 1.12 5.62 0.41 0.08 0.01 29.15 0.06 10.66 9.66 5.83
cciss/c0d7 0.00 1.23 5.42 0.20 0.02 0.01 10.76 0.05 8.87 8.73 4.91
cciss/c0d8 0.00 0.72 3.17 0.20 0.02 0.00 13.09 0.04 12.33 12.21 4.12
cciss/c0d9 0.92 0.82 3.17 0.20 0.03 0.00 18.67 0.04 13.12 12.67 4.27
cciss/c1d0 0.00 2.66 0.41 3.07 0.00 0.01 8.29 0.28 81.91 10.94 3.80
avg-cpu: %user %nice %system %iowait %steal %idle
0.10 0.00 0.20 15.95 0.00 83.74
Device: rrqm/s wrqm/s r/s w/s rMB/s wMB/s avgrq-sz avgqu-sz await svctm %util
cciss/c0d0 0.00 4.19 14.72 0.51 0.10 0.02 15.52 0.17 10.98 9.05 13.79
cciss/c0d1 0.00 0.20 0.31 0.20 0.00 0.00 11.20 0.01 10.20 10.20 0.52
cciss/c0d2 0.00 0.31 0.41 0.41 0.00 0.00 13.00 0.01 7.88 7.88 0.64
cciss/c0d3 0.00 0.31 4.50 0.20 0.02 0.00 9.74 0.05 10.61 10.37 4.88
cciss/c0d4 1.23 0.31 2.76 0.41 0.28 0.00 182.71 0.06 19.97 4.00 1.27
cciss/c0d5 0.00 0.82 3.17 0.20 0.02 0.00 11.64 0.04 11.30 11.30 3.81
cciss/c0d6 2.45 0.51 3.68 0.41 0.28 0.00 143.60 0.07 16.27 5.30 2.17
cciss/c0d7 1.23 0.10 1.94 0.20 0.01 0.00 15.24 0.03 13.33 13.33 2.86
cciss/c0d8 0.00 0.31 0.51 0.41 0.00 0.00 11.56 0.01 8.00 8.00 0.74
cciss/c0d9 0.00 0.10 0.61 0.20 0.00 0.00 10.00 0.01 11.88 11.75 0.96
cciss/c1d0 0.00 3.07 0.00 1.33 0.00 0.01 19.08 0.02 16.77 13.31 1.77
I tried nmon but I did not see anything out of the ordinary...
But when I try to see the NFS stats, nmon (11f-1.el5.rf) coredumps.
I tried the iostat nfs option (kernel 2.6.18-8.1.6.el5, should support it) but it did not show anything.
nfsstat shows no apparent activity...
nfs is normaly only used to put files or modify small files (<1K) "from times to times", while http is used to get files.
From: Les Mikesell <lesmikesell at gmail.com>
> I'd usually blame disk seek time first. If your raid level requires several
> drives to move their heads together and/or the data layout lands on the same
> drive set, consider what happens when your 10 users all want the disk head(s) to
> be in different places. Disk drives allow random access but they really aren't
> that good at it if they have to spend most of their time seeking.
That could be it...
It's always a question of space vs speed...
Thx for all the answers,
JD
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