[Linux-cluster] NFS on GFS architectural issues / problems

[Wendy Cheng]

Riaan van Niekerk wrote:

> Wendy Cheng wrote:
>
>> Riaan van Niekerk wrote:
>>
>>>
>>> My question to you or anyone who is familiar with NFS on GFS, or GFS 
>>> in general, which of the following are still valid issues for the 
>>> current (6.1u4) version of GFS. If all or most of them still apply, 
>>> I can use this as motivation for my customer to strongly consider 
>>> going off NFS on GFS. Removing the NFS from our GFS cluster has been 
>>> on the cards for quite a while, but has not gained momentum due to 
>>> lack of information on the performance gains of such a move (very 
>>> difficult to gage) or the architectural problems/limitations of NFS 
>>> on GFS (for which the following extract is spot-on).
>>
>>
>>
>> These have been worked on and some of them do have test patches ready 
>> to address the issues. However, the changes are non-trivial and may 
>> involve base kernel modifiction that we need to get upstream 
>> (community linux kernel)  acceptance. The efforts take time since we 
>> would like to do it conservatively to preserve GFS1/2 stability. 
>> Unless the posted problems have urgent needs (let us know), the 
>> current NFS-GFS development focus is on failover (Red Hat bugzilla 
>> 132823).
>>
>> Is performance the primary concern you have now ?
>>
>> -- Wendy
>
>
> Yes, mostly. We have a couple of open service requests for stability. 
> They are very intermittent and not reproduceable (and nothing in 
> bugzilla seems to match):


All four issues mentioned are still present in RHEL 3/4 and most of them 
are not GFS specific. As long as it is a cluster filesystem beneath 
linux's nfsd, these issues exist.

I don't plan to defend for NFS - it has inherited problems by its 
nature. Moving to GFS natively is good from performance point of view 
(one layer less). However, I would suggest you do make some efforts to 
understand the problems before taking any significant changes.

Do you have Red Hat support ticket numbers for the mentioned problems 
that I can take a look ?

-- Wendy