Re: [zfs-discuss] compressratio vs. dedupratio

2009-12-15 Thread Craig S. Bell
I take your point Mike. Yes, this seems to be an inconsistency in accounting. I have simply become accustomed to this (esp. when dealing with virtual disk images), so I just don't think about it, but it *is* harder to balance accounts. For instance, if my guest cleans up it's vdisk by writing

Re: [zfs-discuss] compressratio vs. dedupratio

2009-12-15 Thread Mike Gerdts
On Tue, Dec 15, 2009 at 2:31 AM, Craig S. Bell wrote: > Mike, I believe that ZFS treats runs of zeros as holes in a sparse file, > rather than as regular data.  So they aren't really present to be counted for > compressratio. > > http://blogs.sun.com/bonwick/entry/seek_hole_and_seek_data > http:

Re: [zfs-discuss] compressratio vs. dedupratio

2009-12-15 Thread Craig S. Bell
Mike, I believe that ZFS treats runs of zeros as holes in a sparse file, rather than as regular data. So they aren't really present to be counted for compressratio. http://blogs.sun.com/bonwick/entry/seek_hole_and_seek_data http://mail.opensolaris.org/pipermail/zfs-discuss/2008-April/017565.htm

Re: [zfs-discuss] compressratio vs. dedupratio

2009-12-14 Thread Mike Gerdts
On Mon, Dec 14, 2009 at 3:54 PM, Craig S. Bell wrote: > I am also accustomed to seeing diluted properties such as compressratio.   > IMHO it could be useful (or perhaps just familiar) to see a diluted dedup > ratio for the pool, or maybe see the size / percentage of data used to arrive > at dedu

Re: [zfs-discuss] compressratio vs. dedupratio

2009-12-14 Thread Craig S. Bell
I am also accustomed to seeing diluted properties such as compressratio. IMHO it could be useful (or perhaps just familiar) to see a diluted dedup ratio for the pool, or maybe see the size / percentage of data used to arrive at dedupratio. As Jeff points out, there is enough data available to

Re: [zfs-discuss] compressratio vs. dedupratio

2009-12-13 Thread Robert Milkowski
Thank you. However I think it should be more clearly stated in zpool(1M) perhaps even referring to compressratio and explaining that this one is different, plus information as shown below how to get a dedupratio which is similar in meaning to compressratio. On 13/12/2009 11:44, Jeff Bonwic

Re: [zfs-discuss] compressratio vs. dedupratio

2009-12-13 Thread Jeff Bonwick
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 'build

[zfs-discuss] compressratio vs. dedupratio

2009-12-12 Thread Robert Milkowski
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