[CentOS] CentOS7 and NFS

Wed May 13 05:32:27 UTC 2020
Simon Matter <simon.matter at invoca.ch>

> Le 12/05/2020 à 16:10, James Pearson a écrit :
>> Patrick Bégou wrote:
>>>
>>> Hi,
>>>
>>> I need some help with NFSv4 setup/tuning. I have a dedicated nfs server
>>> (2 x E5-2620  8cores/16 threads each, 64GB RAM, 1x10Gb ethernet and 16x
>>> 8TB HDD) used by two servers and a small cluster (400 cores). All the
>>> servers are running CentOS 7, the cluster is running CentOS6.
>>>
>>> Time to time on the server I get:
>>>
>>>       kernel: NFSD: client xxx.xxx.xxx.xxx testing state ID with
>>>      incorrect client ID
>>>
>>> And the client xxx.xxx.xxx.xxx freeze whith:
>>>
>>>       kernel: nfs: server xxxxx.legi.grenoble-inp.fr not responding,
>>>      still trying
>>>       kernel: nfs: server xxxxx.legi.grenoble-inp.fr OK
>>>       kernel: nfs: server xxxxx.legi.grenoble-inp.fr not responding,
>>>      still trying
>>>       kernel: nfs: server xxxxx.legi.grenoble-inp.fr OK
>>>
>>> There is a discussion on RedHat7 support about this but only open to
>>> subscribers. Other searches with google do not provide  useful
>>> information.
>>>
>>> Do you have an idea how to solve these freeze states ?
>>>
>>> More generally I would be really interested with some advice/tutorials
>>> to improve NFS performances in this dedicated context. There are so
>>> many
>>> [different] things about tuning NFS available on the web that I'm a
>>> little bit lost (the opposite of the previous question). So if some one
>>> has "the tutorial"...;-)
>>
>> How many nfsd threads are you running on the server? - current count
>> will be in /proc/fs/nfsd/threads
>>
>> James Pearson
>
> Hi James,
>
> Thanks for your answer. I've configured 24 threads (for 16 hardware
> cores/ 32Threads on the NFS server with this processors)
>
> But it seams that there are buffer setup to modify too when increasing
> the threads number... It is not done.
>
> Load average on the server is below 1....

I'd be very careful with higher thread numbers than physical cores. NFS
threads and so called CPU hyper/simultaneous threads are quite different
things and it can hurt performance if not configured correctly.

Regards,
Simon