Date: Tue, 27 Oct 2009 15:31:24 -0700 From: Jin Guojun <jin@daemonfun.com> To: questions@freebsd.org Subject: What causes random disk access slow down Message-ID: <4AE774BC.8080006@daemonfun.com>
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A 6-7 years old Xeon dual 2.4MHz CPU machine runs FreeBSD 6.4-Release
suddenly becomes
slow on some tasks requiring disk access. Typical things like ls,
objdump etc.
Be more specific, a couple of minutes objdump became a several hours job.
A several seconds "ls -RC" became a 15-minute task (see output below).
It sounds like a hard drive problem, but run sequential disk test on all
drives, their throughput
meet the original disk spec and disks run very quite, at random disk
access, disks generate
some rigid noise, so it looks like a random disk access problem.
This machine has two IDE PATA drives (ignore da0 -- a USB stick), but No
error message has
been recorded in dmesg for any dirve a couple of weeks after the problem
happened.
Machine has been rebooted a few times after slowness occurred, but it
won't help.
Is there anyway/any tool to find out what is going wrong in the system?
-Jin
[165] bsd-ms: ls -RC > Dir
3.756u 19.402s 15:29.37 2.4% 30+2938k 49120+76io 0pf+0w
monitored from the other terms --
[138] bsd-ms: ll ~/Dir
-rw-r--r-- 1 src wheel 6152192 Oct 27 14:53 /home/users/src/Dir
[139] bsd-ms: ll ~/Dir
-rw-r--r-- 1 src wheel 8019968 Oct 27 14:56 /home/users/src/Dir
[140] bsd-ms: ll ~/Dir
-rw-r--r-- 1 src wheel 9915957 Oct 27 14:58 /home/users/src/Dir
tty ad0 ad1 da0 cpu
tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in id
9 365 9.14 6 0.05 12.08 6 0.07 121.91 0 0.00 2 0 1 0 97
0 1020 11.75 87 0.99 17.82 7 0.13 0.00 0 0.00 76 0 14 0 10
0 1005 8.54 262 2.19 52.94 23 1.21 0.00 0 0.00 61 0 29 1 9
0 893 7.54 184 1.36 85.76 34 2.82 0.00 0 0.00 53 0 32 1 14
0 551 3.35 265 0.87 9.38 4 0.04 0.00 0 0.00 47 0 33 1 19
0 594 6.81 201 1.33 37.82 4 0.14 0.00 0 0.00 54 0 16 0 30
0 1106 3.54 252 0.87 55.19 17 0.93 0.00 0 0.00 39 0 33 1 27
0 393 2.88 223 0.63 11.43 2 0.03 0.00 0 0.00 67 0 31 1 1
0 644 4.81 165 0.77 16.00 0 0.01 0.00 0 0.00 87 0 12 1 1
27 339 10.39 180 1.82 15.18 11 0.17 0.00 0 0.00 86 0 13 0 0
32 130 5.06 146 0.72 23.40 46 1.04 0.00 0 0.00 86 0 8 1 5
32 267 8.39 138 1.13 61.09 4 0.22 0.00 0 0.00 73 0 26 1 0
33 340 8.75 222 1.90 61.54 4 0.26 0.00 0 0.00 78 0 21 1 0
32 595 5.85 154 0.88 12.20 3 0.04 0.00 0 0.00 87 0 12 1 0
32 288 5.28 147 0.76 6.00 1 0.01 0.00 0 0.00 86 0 13 1 0
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