[CentOS] NFS v4

[Jean Figarella]

Les Mikesell wrote:
> 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.
> 

At first the sync option was being used, and the freezes happened very 
frequently. About a month and a half ago I started using async, and now 
I get far fewer freezes, like maybe 3 in an 8hr span.

-Jean