[CentOS] bizarre system slowness

Wed Apr 13 20:55:59 UTC 2011
Benjamin Franz <jfranz at freerun.com>

On 04/13/2011 01:34 PM, Cal Webster wrote:
>> tar -zxf with a large file on this machine takes 1.5 minutes, but takes
>> only 10 seconds on any of its siblings. CPU usage seems high while
>> untarring, with lots of user and sys cycles being used, but almost no
>> wait cycles. It doesn't matter whether I untar on a local disk, or on a
>> fiber channel SAN volume, it's slow anyway.

1) Are you untarring from *and* to the SAN volume or is the source on 
the local volume?
2) What kind of local drives? If the local drive is IDE or SATA it is 
possible the machine is using PIO mode. That would match the symptoms of 
very high CPU usage and very slow I/O (yes - I've seen it happen with 
SATA drives with certain Supermicro chipsets).

Benjamin Franz