6.2-R on Dell Poweredge 2950 with Dell PERC 5/i [mfi(4)]

[Scott Long]

David Wolfskill wrote:
> On Thu, May 10, 2007 at 05:14:01PM -0600, Scott Long wrote:
>> ...
>> Not sure that this impression is entirely accurate.  The biggest problem
>> with MFI machines is online RAID management.  The storage driver itself
>> matured very quickly and has been very reliable.
> 
> Ah; good to know:  thank you.
> 
>>> Well, now a colleague is trying to run 6.2-R on one of these 2950s; dmesg
>>> says the controller is:
>>>
>>> mfi0: <Dell PERC 5/i> mem 0xd80f0000-0xd80fffff,0xfc4e0000-0xfc4fffff irq 
>>> 78 at device 14.0 on pci2
>> ...
>>> and the disks looks like:
>>>
>>> mfid0: <MFI Logical Disk> on mfi0
>>> mfid0: 418176MB (856424448 sectors) RAID volume '' is optimal
>>>
>> Looks A OK to me.
> 
> Even better.  :-)
> 
>>> The intended production workload involves creation and deletion of
>>> a large number of files rather rapidly.
>> ...
>> sysctl vfs.ffs.doasyncfree=0 might help.  Running the syncer more 
>> frequently might also help, but I don't recall the sysctl node for
>> that.
> 
> OK; I've relayed your suggestion to my colleague, but haven't heard back
> from her yet.
> 
>> ...
>> Very strange.  No chance that it was due to files that were deleted but
>> still referenced by open apps?
> 
> I don't think so.  She's deployed 13 other boxen over the last few years
> with -- naturally! -- different hardware specs, but all running
> essentailly the same application.
> 
> The big question for her is whether or not the Dell 2950, as specified,
> will do  the job.
> 
>> ...
>> This sounds purely like a filesystem issue, not an MFI driver issue.
> 
> Hmmm... I'll admit to knowing little about RAID configurations; is it
> possible that some RAID configurations might exacerbate problems with
> such a workload -- or that others might be more amenable to it?
> 

If anything, a fast RAID controller will help reduce the lag that you 
get when the syncer does its periodic run.  But beyond that, I can't 
think of anything that would cause problems.

Scott