[CentOS] 3Ware 9550SX and latency/system responsiveness

Mon Sep 24 14:04:47 UTC 2007
Ross S. W. Walker <rwalker at medallion.com>

Simon Banton wrote:
> At 07:46 +0800 24/9/07, Feizhou wrote:
> >>... plus an Out of Memory kill of sshd. Second time around (logged 
> >>in on the console rather than over ssh), it's just the same except 
> >>it's hald that happens to get clobbered instead.
> >
> >Are you saying that running in RAID0 mode with this card and 
> >motherboard combination, you get a memory leak? Who is the culprit?
> I don't know if it's caused by a memory leak or something else, I'm 
> just describing what happens. I would be tempted to suspect the RAM 
> itself if another identical machine didn't have exactly the same 
> issue.
> >>what's left to try?
> >
> >Bug report...
> I've reported the issue to 3ware but they've not responded. I 
> replicated the problem with RHEL AS 4 update 5 and contacted RedHat 
> but they told me evaluation subscriptions aren't supported.
> >>I see there's a new firmware version out today (3ware codeset 
> >> I guess I'll update it and push the whole thing back up 
> >>the hill for another go.
> >
> >I hope that fixes things for you.
> Maybe I'm thinking about this all wrong - maybe this responsiveness 
> issue won't even arise during normal operation, perhaps it's just a 
> symptom of intensive benchmarking when all the resources of the 
> machine are devoted to throwing data at the card/disks as fast as 
> possible. I'm now way out of my depth, frankly.
> I'm going to try the latest firmware upgrade, followed by RHEL/CentOS 
> 5, and finally see if I can replicate with a different card (Areca or 
> LSI, perhaps).
> Thanks for all the feedback, at least I feel as if I've tried every 
> conceivable obvious thing.

In the end it just may be that the card cannot perform under the load
you need it to.

How about trying your benchmarks with the 'disktest' utility from the
LTP (Linux Test Project), the utility can perform benchmarks on raw
block devices and it gives very accurate benchmarks, it is also a
lot easier to setup and use.


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