High IO Wait - PowerEdge 2650 - Perc 3/Di

Tillotson, Jeff Jeff.Tillotson at KnowledgeStorm.com
Fri Jan 19 08:18:35 CST 2007

Hello all,
I have a Dell 2650 with a RAID1 drive connected to a Dell PowerEdge
Expandable RAID controller 3/Di on a SuSE Enterprise Linux 9.3 server
running 2.6.5-7.283-bigsmp #1 SMP Wed Nov 29 16:55:53 UTC 2006 i686 i686
i386 GNU/Linux.

The system is hanging during or after file writes.  If I do something
dd if=/dev/zero of=/home/jefft/file1 bs=512 count=864000 the system will
eventually hang and come back.  Using sar, iostat, top, I can watch
percentage climb and climb until it hangs.  Then, when I can gain access
again, it drops slowly.  The iowait percentage goes up even after the dd
has completed.

I have updated the PERC's firmware to

There is no error messages in dmesg, log messages or anyplace else.  Is
some mechanism for tuning this?  Any help would be greatly appreciated.

Jeff Tillotson
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