Re: Quota on tmpfs

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> I would also guess that sparse files are very rarely used.
> I suspect process 'core' files are written sparse.

I just tried one, and it did not appear so.  But that was just one
test, and quite possibly one of the probably numerous differences
between your test and mine is relevant.  (On 1.4T/sparc and 4.0.1/i386,
I ran "sleep 60" and typed my quitc to get a core dump.  In each case,
"dd conv=notrunc if=sleep.core of=sleep.core" did not change the number
reported by ls -s.)

> I had to uncompress one yesterday and it would have a lot smaller if
> written as a sparse file.

It may have had large runs of 0x00s, but could that have been because
the process's VM contained them?  That is, was it actually sparse when
written, or was it just a file which happened to contain data such that
some disk could be saved by making it sparse?  You say you uncompressed
it, and most compression programs do not distinguish between a sparse
file and a file with long runs of 0x00s, so that's not evidence for
whether it was dumped sparse.

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