[CentOS] nfs (or tcp or scheduler) changes between centos 5 and 6?

[m.roth at 5-cent.us]

James Pearson wrote:
> m.roth at 5-cent.us wrote:
>> Matt Garman wrote:
>>
>>>We have a "compute cluster" of about 100 machines that do a read-only
>>>NFS mount to a big NAS filer (a NetApp FAS6280).  The jobs running on
>>>these boxes are analysis/simulation jobs that constantly read data off
>>>the NAS.
>>
>> <snip>
>> *IF* I understand you, I've got one question: what parms are you using
>> to mount the storage? We had *real* performance problems when we went from
>> 5 to 6 - as in, unzipping a 26M file to 107M, while writing to an
>> NFS-mounted drive, went from 30 sec or so to a *timed* 7 min. The final
>> answer was that once we mounted the NFS filesystem with nobarrier in
>> fstab instead of default, the time dropped to 35 or 40 sec again.
>>
>> barrier is in 6, and tries to make writes atomic transactions; its
>> intent is to protect in case of things like power failure. Esp. if
you're on
>> UPSes, nobarrier is the way to go.
>
> The server in this case isn't a Linux box with an ext4 file system - so
> that won't help ...
>
What kind of filesystem is it? I note that xfs also has barrier as a mount
option.

       mark