Re: Quota file format proposal
Jan Kara (jack@atrey.karlin.mff.cuni.cz)
Tue, 1 Jun 1999 12:55:02 +0200
Hello.
> >> OK, it'll be slower than reserving an entry for every possible uid or
> >> gid and thus being able to go straight to the relevant record, but on
> >> the other hand, it can take up considerably less disc space since only
> >> the records for uid's or gid's with access to that partition need be
> >> stored in its quota file. It's not even much of a slowdown either.
> > It won't be much slower that current implementation as it climbs tree. But
> > this is hidden in ext2 implementation :-). I see the main problem in inserts
> > and deletes. I agree they are not very often but spending 2 seconds on one
> > insert seems too much to me :-). I'm searching the net for some interresting
> > structures :-).
>
> Why bother? The quota file can already be sparse.
I know but there are filesystem limits which prevents us from using all 31-bits.
There is 2GB limit on 32-bit archs but it doesn't bother us as it will be hopefully
removed. But there is 16GB limit on ext2 using 1KB blocks if I summed it well...
And as we have 40-bytes long structures we need 128GB to be able to use all UIDs.
For this we need at least 4kb blocks which are not used very much... I think it is
good to think whether it wouldn't be good to switch to some other structure.
Honza.
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