zfs quota question

[Holger Kipp]

On Tue, Oct 07, 2008 at 03:12:59AM -0700, Jeremy Chadwick wrote:
> On Tue, Oct 07, 2008 at 12:07:26PM +0200, Holger Kipp wrote:
> > On Tue, Oct 07, 2008 at 02:54:37AM -0700, Jeremy Chadwick wrote:
> > > On Tue, Oct 07, 2008 at 05:32:43PM +0800, lhmwzy wrote:
> > > > I create a zfs volume pool/lhm and give it quota 1M use "zfs set
> > > > quota=1m pool/lhm"
> > 
> > > I can confirm and reproduce what you're seeing.
> > > 
> > > Based on all of the ZFS documentation and examples I've read, it appears
> > > to be a bug in FreeBSD ZFS.
> > > 
> > > CC'ing pjd@, who maintains ZFS on FreeBSD.
> > 
> > I can't confirm this on a recent 7-STABLE (yesterday):
> > 
> > intserv2# zfs set quota=1m tank/test
> > intserv2# cp /usr/ports/distfiles/samba-3.0.32.tar.gz /tank/test/
> > cp: /tank/test/samba-3.0.32.tar.gz: Disc quota exceeded
> 
> Interesting.  The system I'm testing on:
> 
> FreeBSD icarus.home.lan 7.1-PRERELEASE FreeBSD 7.1-PRERELEASE #0: Thu Oct  2 03:04:20 PDT 2008 root at icarus.home.lan:/usr/obj/usr/src/sys/PDSMI_PLUS_RELENG_7_amd64 amd64
> 
> Can you provide the output from "zfs get all tank tank/test"?
> Below are mine.
> 
> Note that for the testing, I set the quota on storage/home to 4G, and
> did "dd if=/dev/zero of=/home/filler bs=1g count=8".  I've since
> set the quota back to 16G.
> 
> NAME          PROPERTY       VALUE                  SOURCE
> storage       compressratio  1.02x                  -
> 
> storage/home  type           filesystem             -
> storage/home  compressratio  1.25x                  -

I am not sure if you get correct results with /dev/zero and
enabled compression. A file that only contains null bytes won't 
grow very fast in compressed form.

You might want to create storage/test and disable compression
for this, then set a limit of 1M or larger (if you like) and try
once again.

I currently have a pool defined without general compression and
just used

# zfs create tank/test
# zfs set quota=1m tank/test
# cp /usr/ports/distfiles/samba-3.0.32.tar.gz /tank/test/
cp: /tank/test/samba-3.0.32.tar.gz: Disc quota exceeded

# zfs destroy tank/test

and compressration is a very steady 1.00x ;-)

Best regards,
Holger Kipp