[Beowulf] LSI Megaraid stalls system on very high IO?

[Joe Landman]

On 7/31/14, 1:55 PM, mathog wrote:
> On 31-Jul-2014 10:36, Joe Landman wrote:
>> On 7/31/14, 12:37 PM, mathog wrote:
>>> Any pointers on why a system might appear to "stall" on very high IO
>>> through an LSI megaraid adapter?  (dm_raid45, on RHEL 5.10.)
>> What IO scheduler are you using?
>>
>>     cat /sys/block/sd*/queue/scheduler
>
> % cat /sys/block/sd*/queue/scheduler
> noop anticipatory deadline [cfq]
> noop anticipatory deadline [cfq]
> noop anticipatory deadline [cfq]

Switch them to deadline or noop.

echo deadline > /sys/block/sda/queue/scheduler

rinse and repeat for other devices.


>
> Thanks,
>
> David Mathog
> mathog at caltech.edu
> Manager, Sequence Analysis Facility, Biology Division, Caltech


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