Thoughts on Quotas

Rumko rumcic at
Tue Sep 28 07:34:04 PDT 2010

Michael Neumann wrote:

> Am Dienstag, den 28.09.2010, 02:42 -0600 schrieb Samuel J. Greear:
>> On Mon, Sep 27, 2010 at 10:34 PM, Chris Turner
>> Quota systems are also often overloaded for accounting purposes, so
>> before you think "well, quota's aren't useful in that scenario!", I
>> have definitely tied quota's into billing at more than one employer
>> under different scenarios in which the quota systems didn't actually
>> enforce any limits on storage utilization. As an aside, perhaps this
>> should be considered for any future quota implementation.
>> It is certainly possible that I am in the minority, but I definitely
>> see hundreds of thousands as necessary now, it will be millions in the
>> future.
> Sure! I agree completely. My concern was just that historical data is
> not taken into account, and some evil people can destroy your quota
> system if they repetitively write to files without changing the file
> size itself. I think for most cases quotas based on accumulating file
> size as Matt has suggested will do. But will it also do when using
> jails? I don't think it plays well with jails because there you want a
> per-jail quota and not a per-user within a jail.
> Now for my scenario (file/backup server) this per-user quota API would
> do perfect. But then, as I want to give each user a PFS anyway (and I do
> not think there are more than 100 users), so that each user can
> configure history retention and mirroring individually, a per-PFS quota
> sounds appealing as well, especially as ZFS has a similar feature :).

I also agree with the per-PFS quota system being quite useful and not to be
ignored for real-world scenarios.
e.g. for vkernel usage, I don't care which user uses how much inside the
vkernel, but I do care that _that_ vkernel does not use more than I want it to
(think of a vkernel being a web server/mail server/whatever and having
it's /data a NFS mount that is a PFS on the host system, I couldn't care less
if it has 1K users and how much each of them abuses the disk space, as long as
the NFS mount/PFS itself does not take more than e.g. 1GB of disk space on the
host system).

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