[lustre-discuss] Lustre project quotas and project IDs

[Passerini Marco]

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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