[patch] giant-less quotas for UFS

[Nicolas KOWALSKI]

Eric Anderson <anderson at centtech.com> writes:

> Nicolas KOWALSKI wrote:
>> Eric Anderson <anderson at centtech.com> writes:
>>
>>> Nicolas KOWALSKI wrote:
>>>> Yes, this is exactly what is happening. To add some precision, some
>>>> students here use calculation applications
>>>> that allocate a lot of disk space, ususally more than their allowed
>>>> home quotas; when by error they launch these apps in their home
>>>> directories, instead of their workstation dedicated space, it makes
>>>> the server go to its knees on the NFS client side.
>>> When you say 'to it's knees' - what do you mean exactly?  How many
>>> clients do you have, how much memory is on the server, and how many
>>> nfsd threads are you using?  What kind of load average do you see
>>> during this (on the server)?
>> Sorry for the imprecision.
>> The server is a Dual-Xeon 2.8Ghz, 2GB of RAM, using SCSI3 Ultra320
>> 76GB disks and controller. It is accessed by NFS from ~100 Unix
>> (Linux, Solaris) clients, and by Samba from ~15 Windows XP. The
>> network connection is GB ethernet.
>> During slowdowns, it's only from a NFS client view that the server
>> does not respond. For example, a simple 'ls' in my home directory is
>> almost immediate, but when it slows down, it can take up to 2 minutes.
>> On the server, the load average goes to 0.5, compared to a default
>> maximum of 0.15-0.20. The nfsd processus shows them in the state
>> "biowr" in top, but nothing is really written, because the quotas
>> system block any further writes to the user exceeding her/his quotas.
>>
>
> In this case (which is what I suspected), try bumping up your nfsd
> threads to 128.  I set mine very high (I have around 1000 clients),
> and I can say there aren't really ill-effects besides a bit of memory
> usage (which you have plenty of).  I suspect increasing the threads
> will neutralize this problem for you.

Using 128 nfsd threads, I stressed the server, by running on a NFS
client a small C program, writting continuously in a file, so that the
user "biguser" (account stored on /export/home2) exceeds his quota.

It half-works: during the test, users working on another disk
(/export/home) did not see any difference, but users working on the
same disk that "biguser" (/export/home2) where almost halted.

So, this is better, because before everybody was halted, but there is
still a problem.

Any other tips ?

Thanks,
-- 
Nicolas