Dane Jasper dane@sonic.net writes:
I wasn't aware that you could do default per-user quotas, so I decided to give this a try. After fixing up a couple important folks like root and www so that they would have no quota, I have the following:
User and group quotas don't apply to root. (Tree quotas do, of course.)
The filer seems a bit slower than usual. There are about 13000 users, is managing quotas in the NetApp unfeasible? Perhaps this is just my perception, CPU utilization is still at 50%, which seems pretty normal.
Quotas will slow some operations down. Default quotas are only a convenience. Every time the default quota is used for a user, a new entry in the quota table (or whatever) is created. So, the performance impact of 13000 users is the same whether or not you are using default user quotas.
For some users, I'm getting reports of 700+ megs of usage, but I can only find 40 megs worth of files owned by them. Any clues on this?
They may own data in other directories in the tree. For example, if /home is the tree, /home/bob may only contain 50MB. But, bob's usage will be 100MB if /home/sue has another 50MB of data owned by bob.
We have YP - can I map usernames to UIDs using YP, or will this be a large amount of overhead?
Yes, you can. UID to username mapping is typically only used for infrequent operations: CIFS authentication, reading in the quota table, etc. The overhead shouldn't be too bad.
Could someone from NetApp let us know when the overhead is bad? (I'm not using a PDC yet, so ACLs aren't a factor for me. Actually, our CIFS load is so low (< 0.5%), it doesn't matter much at all.
What sort of message will the user get if they run out of space? Will it just say filesystem full, or will it actually mention quota? Any ideas how sendmail will handle it when they get email?
Most Unix systems' write() calls will fail, returning EDQUOT. Some badly-written userland programs (especially ones written by your average user) don't check the return value of write(), and can loop forever. Once or twice, this has sent the load on a NetApp here into the stratosphere (basically: write, fail, write, fail, ... very rapidly).
Exceeded quotas are also logged to /etc/messages.
I'd recommend using a userland program (on login) to regularly tell users how close they are to exceeding their quota, in addition to monitoring quotas for your own information.
- Dan