[lustre-discuss] Lustre project quotas and project IDs

[Andreas Dilger]

Of course my preference would be a contribution to improving the name-projid mapping in the "lfs project" command under LU-13335 so this would also help other Lustre users manage their project IDs.

One proposal I had in LU-13335 that I would welcome feedback on was if a name or projid did not exist in /etc/projid that the lfs tool would fall back to doing a name/uid lookup in /etc/passwd (or other database as configured in /etc/nsswitch.conf).

This would avoid the need to duplicate the full UID database in /etc/projid for the common case of projid = uid, and allows using LDAP, NIS, AD, sssd, etc. for projid lookup without them having explicit support for a projid database.

This behavior could optionally be configured with a "commented-out" directive at the start of /etc/projid, like:

 #lfs fallback: passwd

or "group" or "none".  If all the projects are defined in the passwd database, then potentially just this one line is needed in /etc/projid, or not at all if "passwd" is the default fallback.

Would this meet your need for using an external database, while still allowing your development efforts to produce a solution that helps the Lustre community?

Of course at some point it wouod be desirable to have a dedicated projid database supported by glibc, but that is would take much more time and effort to implement and deploy, while the passwd/group fallback can be handled internally by the lfs command.

Cheers, Andreas

On Mar 17, 2023, at 04:10, Passerini Marco <marco.passerini at cscs.ch> wrote:



Hi Andreas,


I'm talking the order of ~10,000s of project IDs.

I've been thinking the same as you, that is, doing PROJID=1M + UID  etc. However, in our case, it might be better to rely on some scripting and an external DB, to keep track of the latest added ID, so that we could increment the highest value by 1 on new ID creation. The highest value could as well be looked up in:


/proc/fs/lustre/osd-ldiskfs/myfs-MDT0000/quota_slave_dt/acct_project

Regards,

Marco Passerini

________________________________
From: Andreas Dilger <adilger at whamcloud.com>
Sent: Thursday, March 16, 2023 11:35:16 PM
To: Passerini Marco
Cc: lustre-discuss at lists.lustre.org
Subject: Re: [lustre-discuss] Lustre project quotas and project IDs

On Mar 16, 2023, at 04:50, Passerini Marco <marco.passerini at cscs.ch<mailto:marco.passerini at cscs.ch>> wrote:

By trial and error, I found that, when using project quotas, the maximum ID available is 4294967294. Is this correct?

Yes, the "-1" ID is reserved for error conditions.

If I assign quota to a lot of project IDs, is the performance expected to go down more than having just a few or is it fixed?

Probably if you have millions or billions of different IDs there would be some performance loss, at a minimum just because the quota files will consume a lot of disk space and memory to manage.  I don't think we've done specific scaling testing for the number of project IDs, but it has worked well for the "expected" number of different IDs at production sites (in the 10,000s).

I've recommended to a few sites that want to have a "unified" quota to use e.g. PROJID=UID for user directories, PROJID=1M + UID for scratch, and PROJID=2M+N for independent projects, just to make the PROJIDs easily identified (at least until someone implements LU-13335 to do projid<->name mapping).

How many IDs were you thinking of using?

Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Whamcloud







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