On Mar 16, 2023, at 04:50, Passerini Marco 
<[email protected]<mailto:[email protected]>> 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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