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On Nov 1, 2011, at 21:40, Eugene Vilensky <evilensky AT gmail DOT com> wrote:

> On Tue, Nov 1, 2011 at 8:59 AM, Francis Swasey <Frank.Swasey AT uvm DOT edu> 
> wrote:
> 
> Before I ask EMC and RedHat to point fingers at each other, I thought I'd 
> ping you illustrious
> folk to see if any of you know of anything that would indicate I have either 
> royally screwed up
> by choosing XFS or if perhaps you have more experience with XFS and can 
> suggest something in
> the way of tuning to "make it stop" (right now, I'm using mostly default 
> options, with the
> single exception of adding the inode64 option to allow inodes to be placed 
> beyond the first 4TB
> of the 17TB disk).
> 
> Thanks for any pointers!
> 
> Frank, is there any opportunity for you to take the storage node offline, 
> remove networker from the picture, and put some sequential and then random IO 
> stress on the subsystem?


There is, as long as I empty off these 34TB of data first.  I will get started 
on that.  I did performance testing of XFS vs EXT4 in a different environment 
before I deployed here.  Perhaps, there is something unique with the  QLogic 
HBA's or the NexSan itself here.

> 
> I have a 24TB XFS AFTD volume right now, but few clients to stress it (aside 
> maybe for staging operations...); however it stayed rock solid during 
> benchmarking (dd, bonnie++, iozone).

I am a firm believer in teach vs give (as in fish...) - So, if you don't mind, 
would you care to explain why you chose to use those mount/mkfs options?  
Perhaps there is some documentation that I have missed in my various searches.

> 
> file system mount options:
> rw,noatime,nodiratime,logbufs=8,logbsize=256K,nobarrier,osyncisdsync,inode64
> 
> create options: 
> mkfs.xfs -l version-2 -d su=128k,sw=11  
> 
> to match raid stripe size and the number of RAID bands in the device (22 
> disks, RAID1+0)
> 
> At boot:
> elevator=noop
> 
> and a sizeable read-ahead for sequential reads (with read-ahead completely 
> disabled on the RAID controller itself):
> /sbin/blockdev --setra 16384 /dev/sdxx

And above all, thank you for being willing to share your knowledge.

Frank
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