zfs quota question

[Jeremy Chadwick]

On Tue, Oct 07, 2008 at 12:17:55PM +0200, Pawel Jakub Dawidek 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"
> > > 
> > > #zfs get all pool/lhm
> > > zfs get all pool/lhm
> > > [ttyp0][5:22:12pm]
> > > NAME      PROPERTY       VALUE                  SOURCE
> > > pool/lhm  type           filesystem             -
> > > pool/lhm  creation       Tue Oct  7 17:14 2008  -
> > > pool/lhm  used           1.00M                  -
> > > pool/lhm  available      0                      -
> > > pool/lhm  referenced     1.00M                  -
> > > pool/lhm  compressratio  7.25x                  -
> 
> Turn compression off and retry.

Yep, that's the key!

# zfs set quota=4g storage/home
# zfs set compression=off storage
# zfs get compression,quota,mountpoint
NAME          PROPERTY     VALUE         SOURCE
storage       compression  off           local
storage       quota        none          default
storage       mountpoint   /storage      default
storage/home  compression  off           inherited from storage
storage/home  quota        4G            local
storage/home  mountpoint   /home         local

# dd if=/dev/zero of=/home/filler bs=1g count=8
dd: /home/filler: Disc quota exceeded
4+0 records in
3+1 records out
3306553344 bytes transferred in 62.566567 secs (52848566 bytes/sec)

# df -h /home
Filesystem      Size    Used   Avail Capacity  Mounted on
storage/home    4.0G    4.0G      0B   100%    /home

I had no idea compression could cause this.  A useful feature, but
obviously can result in misleading results...  :-)

Thanks as usual, Pawel!

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |