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

Christopher Samuel samuel at unimelb.edu.au
Wed May 13 16:41:07 PDT 2015

On 14/05/15 08:57, mathog wrote:

> cat /sys/block/dm*/queue/scheduler
> none
> none
> How is it possible to mount a volume, Raid or no, with no scheduler???

I think you're looking in the wrong place; you need to look at the sys
files for the disk (sda, sdb, or variations if your RAID controller
registers them differently) rather than the Device Mapper (DM) entries.
 They don't have IO schedulers associated with them.

Regarding writing the file back, I suspect you're seeing all the dirty
pages for the file being written getting charged to that process.

As for swap, could it be someone built it with a kickstart that defined
it that way?

 Christopher Samuel        Senior Systems Administrator
 VLSCI - Victorian Life Sciences Computation Initiative
 Email: samuel at unimelb.edu.au Phone: +61 (0)3 903 55545
 http://www.vlsci.org.au/      http://twitter.com/vlsci

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