[CentOS] NFS v4

[Les Mikesell]

Jean Figarella wrote:

>>> Under real user load though it just fell on its arse very
>>> quickly and a quick fall back to v3 was implemented. Maybe the
>>> EL5 implementation behaves better?
>>
>> I use one of my CentOS 5 boxen for low-load fileserver with
>> NFS4. I've been noticing that although MP3s plays fine from
>> that box, it can take a minute or two to write a dozen
>> tags--something that should happen in the blink of an eye. I've
>> been wondering what the problem is. Maybe it's NFS4!
>>
> 
> I've been experiencing 5 to 20 seconds freezes ever since I upgraded my 
> nfs server. This serves about 30 people. Anytime someone writes a big 
> file to their home directory, the freezes happen. You can experience the 
> freezes when browsing the internet, I guess because firefox is 
> constantly writing data (cache, cookies, etc...). Other apps freeze up too.
> 
> Now the question on my side is: can I force centos4 for serve nfs3 as 
> opposed to nfs4. If I am not mistaken this is dependent on the client?
> 
> The reason Im asking is that if I can force the server to serve nfs3 
> then the clients will default to nfs3 themselves. right?

Are these mounted with the sync or async option?  If it is sync, the 
client waits for the physical flush to disk to happen on every 
operation, something that is horribly slow and that you never do for 
local disks except for transaction boundaries in databases and other 
unusual situations.

-- 
   Les Mikesell
    lesmikesell at gmail.com