On Thu, Jun 5, 2008 at 2:11 PM, Erik Trimble <[EMAIL PROTECTED]> wrote: > > Quotas are great when, for administrative purposes, you want a large > number of users on a single filesystem, but to restrict the amount of > space for each. The primary place I can think of this being useful is > /var/mail
Not really. Controlling mail usage needs to be done by the mail app - simply failing a write is a terrible way to implement policy. > The ZFS filesystem approach is actually better than quotas for User and > Shared directories, since the purpose is to limit the amount of space > taken up *under that directory tree*. Quotas do a miserable job with > Shared directories, and get damned confusing if there is the ability of > anyone else to write to your User directory (or vice versa). Erm, that's backwards. You want quotas to control shared directories. In particular, you can't use ZFS filesystem to control usage in a single directory (essentially by definition). What we use quotas for there is to make sure a bad user (or rogue application) is controlled and can't fill up a filesystem, thereby impacting other users. > Remember, that quotas aren't free, and while we have seen some > performance problems with the '10,000 ZFS filesystems' approach, there > are performance issues to be had when trying to keep track of 10,000 > user quotas on a file system, as well. I can't say they are equal, but > don't think that quotas are just there for the implementing. There's a > penalty for them, too. But 5-10,000 users with quotas worked just fine on a supersparc based machine in the last millenium. Even on a decent modern machine that number of filesystems could best be described as painful. The reality is that there are something like 3 orders of magnitude difference in cost between traditional ufs quotas and using zfs filesystems to try and emulate the same thing. (Although I have to say that, in a previous job, scrapping user quotas entirely not only resulted in happier users, much less work for the helpdesk, and - paradoxically - largely eliminated systems running out of space.) -- -Peter Tribble http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
