[OpenAFS] openafs performace problems

[Rich Sudlow]

Mattias Pantzare wrote:
> On Tue, Jan 6, 2009 at 17:10, Rich Sudlow <rich@nd.edu> wrote:
>> Esther Filderman wrote:
>>> To some degree, OpenAFS will always write slower than standard NFS,
>>> because AFS is actually making sure it's not writing crap.  NFS will
>>> happily write stuff at blazingly fast speeds, not caring whether the
>>> data it writes is sane or corrupted.
>> The reason NFS appears to be faster is because you're not doing an
>> apple - apples comparision - if you were you would have to turn off
>> attribute caching on NFS - at that point you'd find that performance
>> is essentially equal
> 
> Why would you turn off attribute caching? That is a part of NFS.

You're correct you generally wouldn't - But if you are truly comparing
NFS and OpenAFS you would need to.

> 
> Why would attribute caching make the test be an apples - oranges comparison?

Because you have no cache coherancy on NFS to verify that data is 
propogated out and seen simultaneously on multiple clients
(V2 & 3)  whereas with OpenAFS that cache coherancy is there.

Rich


-- 
Rich Sudlow
University of Notre Dame
Center for Research Computing
128 Information Technology Center
PO Box 539
Notre Dame, IN 46556-0539

(574) 631-7258 office phone
(574) 631-9283 office fax