OT: I/O bound?
Denis Beauchemin
Denis.Beauchemin at USHERBROOKE.CA
Tue Apr 27 14:38:21 IST 2004
Hi,
One of my servers (Xeon 2.4, 1.5GB, 73GB 10K rpm U160 disk) running MS
4.29.7-1 + SA 2.63 + sendmail 8.12.10-1 on a RHEL 3 AS (all patches
applied) seems to be suffering from high disk access:
# iostat -dk 5|awk '/^Device/&&p!=1{print;p=1}/^dev/{print}'
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
dev8-0 160.89 132.67 685.66 10411181 53804828
dev8-0 224.34 14.91 941.23 68 4292
dev8-0 246.06 16.28 1056.49 64 4152
dev8-0 190.12 14.46 827.95 60 3436
dev8-0 133.94 11.76 602.71 52 2664
dev8-0 160.34 7.68 720.68 36 3380
dev8-0 156.07 25.24 672.82 104 2772
dev8-0 138.39 6.25 777.68 28 3484
dev8-0 295.57 13.99 1234.50 60 5296
dev8-0 132.68 4.36 574.29 20 2636
dev8-0 74.00 8.39 344.65 40 1644
dev8-0 94.46 8.87 414.19 40 1868
dev8-0 231.74 143.07 824.18 568 3272
dev8-0 176.82 10.91 761.82 48 3352
dev8-0 136.15 3.76 609.39 16 2596
dev8-0 207.82 9.78 880.20 40 3600
dev8-0 171.86 143.28 614.07 672 2880
dev8-0 122.09 2.79 534.88 12 2300
dev8-0 200.27 109.49 766.40 404 2828
It reads just a little bit but writes so much. I run a caching NS
(bind, as supplied by RH) and use tmpfs for
/var/spool/MailScanner/incoming. Anything I can do to make it go
faster? Is there some program I can run to figure out which program
does all this I/O?
Here is the output of some commands:
# free
total used free shared buffers cached
Mem: 1545056 1456104 88952 0 232744 881236
-/+ buffers/cache: 342124 1202932
Swap: 2048276 309720 1738556
# vmstat 5
procs memory swap io
system cpu
r b swpd free buff cache si so bi bo in cs us sy
id wa
5 0 308612 35000 232736 885600 8 7 57 61 194 24 41 15
31 13
2 0 308608 74856 232736 885560 0 0 0 786 411 1587 67
24 0 9
0 0 308608 79408 232736 886624 0 0 13 1028 654 1886 34 17
16 34
2 0 308608 62488 232740 885744 0 0 6 441 454 3994 62
21 8 8
3 4 308608 53280 232740 885772 0 0 7 1161 456 1564 55 16
17 12
0 0 308608 66268 232752 885820 0 0 6 554 399 1643 44 24
14 18
3 2 308608 75588 232756 886092 0 0 3 550 419 1656 37 19
33 10
0 2 308556 50620 232784 886068 0 0 1 675 499 2065 40 15
21 25
1 0 308548 57600 232800 886264 0 0 1 269 269 1199 30 14
51 4
5 1 308548 49644 232836 886432 0 0 0 399 349 1864 42 15
34 9
2 0 308548 33224 232884 886832 0 0 3 562 378 1763 53 24
10 13
6 0 308548 59540 232896 886652 0 0 9 418 271 1260 59 18
13 10
1 0 308548 22212 232908 886852 1 0 4 606 384 2234 58 20
13 9
4 0 308544 56104 232660 887224 0 0 12 850 402 3748 35 20
25 21
2 0 308544 62052 232660 887496 0 0 2 710 372 1457 57 17
15 11
4 9 308500 71140 232676 887996 2 0 11 876 449 3826 65
33 0 2
# top
09:35:19 up 1 day, 1:22, 1 user, load average: 5.12, 4.80, 5.28
145 processes: 144 sleeping, 1 running, 0 zombie, 0 stopped
CPU states: cpu user nice system irq softirq iowait idle
total 23.7% 0.0% 10.6% 0.0% 0.0% 65.0% 0.4%
cpu00 17.4% 0.0% 12.6% 0.0% 0.0% 68.9% 0.9%
cpu01 30.0% 0.0% 8.7% 0.0% 0.0% 61.1% 0.0%
Mem: 1545056k av, 1490064k used, 54992k free, 0k shrd, 232876k
buff
1161456k actv, 265116k in_d, 7252k in_c
Swap: 2048276k av, 308184k used, 1740092k free 897560k
cached
PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND
23985 root 23 0 44736 31M 2348 S 17.0 2.0 0:00 1
MailScanner
23987 root 25 0 3348 3348 1920 S 3.4 0.2 0:00 1 pyzor
23814 root 23 0 4588 4588 1664 D 2.9 0.2 0:01 1
mailscanner-mrt
7 root 15 0 0 0 0 SW 2.4 0.0 12:22 1 kswapd
1726 named 25 0 26668 25M 1568 S 1.4 1.7 19:41 1 named
4093 root 20 0 44472 22M 2112 S 0.4 1.4 3:26 1
MailScanner
23980 root 21 0 42852 28M 2260 S 0.4 1.8 0:00 1
MailScanner
Thanks!
Denis
--
_
°v° Denis Beauchemin, analyste
/(_)\ Université de Sherbrooke, S.T.I.
^ ^ T: 819.821.8000x2252 F: 819.821.8045
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