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Is anyone else having major I/O peaks due to logrotate or other jobs
running simultaneously across multiple guests. I have one KVM server
running Centos 5.4 with local disk that is seriously suffering as most
of the guests rotate their syslog at the same time.<br>
<br>
Looking at the KVM server I'm seeing<br>
<br>
11:00:01 PM CPU %user %nice %system %iowait
%steal %idle<br>
03:40:01 AM all 0.07 0.00 2.74 0.93
0.00 96.26<br>
03:50:01 AM all 0.07 0.00 1.17 1.18
0.00 97.58<br>
04:00:01 AM all 0.08 0.00 1.51 0.82
0.00 97.59<br>
04:10:02 AM all 0.53 0.03 15.31 51.61
0.00 32.53<br>
04:20:01 AM all 0.28 0.12 4.12 22.21
0.00 73.27<br>
04:30:01 AM all 0.07 0.00 0.80 1.21
0.00 97.92<br>
04:40:01 AM all 0.07 0.00 2.60 1.81
0.00 95.52<br>
04:50:01 AM all 0.08 0.00 0.79 1.44
0.00 97.69<br>
<br>
On one of the guests running Centos 4.6 the impact is so bad I get DMA
timeout errors in the syslog, and occasional kernel panics.<br>
<br>
Mar 11 04:05:04 localhost kernel: hda: dma_timer_expiry: dma status ==
0x21<br>
Mar 11 04:05:14 localhost kernel: hda: DMA timeout error<br>
Mar 11 04:05:14 localhost kernel: hda: dma timeout error: status=0x50 {
DriveReady SeekComplete }<br>
Mar 11 04:05:14 localhost kernel: <br>
Mar 11 04:05:14 localhost kernel: ide: failed opcode was: unknown<br>
Mar 11 04:05:59 localhost kernel: hda: dma_timer_expiry: dma status ==
0x21<br>
Mar 11 04:06:14 localhost kernel: hda: DMA timeout error<br>
Mar 11 04:06:14 localhost kernel: hda: dma timeout error: status=0x50 {
DriveReady SeekComplete }<br>
<br>
<br>
One reference I've found is at <br>
* <a class="moz-txt-link-freetext" href="http://lonesysadmin.net/linux-virtual-machine-tuning-guide/">http://lonesysadmin.net/linux-virtual-machine-tuning-guide/</a><br>
<br>
This suggests avoiding running scheduled jobs simultaneously across
guests, and suggests using a random sleep.<br>
<br>
Does anyone else have suggestions on reducing the impact of
cron/logrotate.<br>
<br>
<div class="moz-signature">-- <font face="Verdana, Helvetica, Arial"><font
size="2"><span style="font-size: 10pt;"><br>
<b>Steven Ellis - Director of Worldwide Engineering,</b><br>
<b>Bulletin.Net Inc</b> - <a href="http://www.bulletin.net/">http://www.bulletin.net/</a>
<br>
<br>
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