[CentOS] 32-bit kernel+XFS+16.xTB filesystem = potential disaster (was:Re: ZFS @ centOS)

Wed Apr 6 20:08:52 UTC 2011
Warren Young <warren at etr-usa.com>

On 4/6/2011 1:16 PM, Lamar Owen wrote:
> There are other issues with XFS and 32-bit; see:
> http://bugs.centos.org/view.php?id=3364
> and
> http://www.mail-archive.com/scientific-linux-users@listserv.fnal.gov/msg05347.html
> and google for 'XFS 32-bit 4K stacks' for more of the gory details.

Thanks for the info.

The problem seems to be tied to LVM and high amounts of I/O, 
particularly writes.  None of that applies to this application.  The 
filesystem is a plain-old partition, the array is mostly going to be 
read-only, and due to a bottleneck elsewhere in the system, the peak 
read rate can't be higher than 20 Mbyte/s.

(If you're wondering, then, why I bothered to benchmark the system at 
all, it's because we get much higher I/O rates when initially loading 
the array up, so that the low write speed of ZFS-FUSE would have 
increased that initial load from days to weeks.)

That load went off without a hitch, so we've probably already done the 
worst thing to this server that it will ever see.  (Kind of like the old 
advice for happiness: eat a bug every morning, and nothing worse will 
happen to you for the rest of the day.)

We'll test it under load before shipping it anyway, however.