It is by design. The idea is to report the dedup ratio for the data you've actually attempted to dedup. To get a 'diluted' dedup ratio of the sort you describe, just compare the space used by all datasets to the space allocated in the pool. For example, on my desktop, I have a pool called 'builds' with dedup enabled on some datasets:
$ zfs get used builds NAME PROPERTY VALUE SOURCE builds used 81.0G - $ zpool get allocated builds NAME PROPERTY VALUE SOURCE builds allocated 47.4G - Thus my diluted dedup ratio is 81.0 / 47.4 = 1.71. Jeff On Sat, Dec 12, 2009 at 10:06:49PM +0000, Robert Milkowski wrote: > Hi, > > The compressratio property seems to be a ratio of compression for a > given dataset calculated in such a way so all data in it (compressed or > not) is taken into account. > The dedupratio property on the other hand seems to be taking into > account only dedupped data in a pool. > So for example if there is already 1TB of data before dedup=on and then > dedup is set to on and 3 small identical files are copied in the > dedupratio will be 3. IMHO it is misleading as it suggest that on > average a ratio of 3 was achieved in a pool which is not true. > > Is it by design or is it a bug? > If it is by design then having an another property which would give a > ratio of dedup in relation to all data in a pool (dedupped or not) would > be useful. > > > Example (snv 129): > > > mi...@r600:/rpool/tmp# mkfile 200m file1 > mi...@r600:/rpool/tmp# zpool create -O atime=off test /rpool/tmp/file1 > > mi...@r600:/rpool/tmp# ls -l /var/adm/messages > -rw-r--r-- 1 root root 70993 2009-12-12 21:50 /var/adm/messages > mi...@r600:/rpool/tmp# cp /var/adm/messages /test/ > mi...@r600:/rpool/tmp# sync > mi...@r600:/rpool/tmp# zfs get compressratio test > NAME PROPERTY VALUE SOURCE > test compressratio 1.00x - > > > mi...@r600:/rpool/tmp# zfs set compression=gzip test > mi...@r600:/rpool/tmp# cp /var/adm/messages /test/messages.1 > mi...@r600:/rpool/tmp# sync > mi...@r600:/rpool/tmp# zfs get compressratio test > NAME PROPERTY VALUE SOURCE > test compressratio 1.27x - > > > mi...@r600:/rpool/tmp# zfs get compressratio test > NAME PROPERTY VALUE SOURCE > test compressratio 1.24x - > > > > > > mi...@r600:/rpool/tmp# zpool destroy test > mi...@r600:/rpool/tmp# zpool create -O atime=off test /rpool/tmp/file1 > mi...@r600:/rpool/tmp# zpool get dedupratio test > NAME PROPERTY VALUE SOURCE > test dedupratio 1.00x - > > > mi...@r600:/rpool/tmp# cp /var/adm/messages /test/ > mi...@r600:/rpool/tmp# sync > mi...@r600:/rpool/tmp# zpool get dedupratio test > NAME PROPERTY VALUE SOURCE > test dedupratio 1.00x - > > mi...@r600:/rpool/tmp# cp /var/adm/messages /test/messages.1 > mi...@r600:/rpool/tmp# sync > mi...@r600:/rpool/tmp# zpool get dedupratio test > NAME PROPERTY VALUE SOURCE > test dedupratio 1.00x - > mi...@r600:/rpool/tmp# cp /var/adm/messages /test/messages.2 > mi...@r600:/rpool/tmp# sync > mi...@r600:/rpool/tmp# zpool get dedupratio test > NAME PROPERTY VALUE SOURCE > test dedupratio 2.00x - > > mi...@r600:/rpool/tmp# rm /test/messages > mi...@r600:/rpool/tmp# sync > mi...@r600:/rpool/tmp# zpool get dedupratio test > NAME PROPERTY VALUE SOURCE > test dedupratio 2.00x - > > > > > > > > -- > Robert Milkowski > http://milek.blogspot.com > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
