I have noticed that dedup is discussed a lot in this list right now.. Starting to experiment with dedup=on, I feel it would be interesting in knowing exactly how efficient dedup is. The problem is that I''ve found no way of checking this per file system. I have turned dedup on for a few file systems to try it out: peo at opensolaris-fs:~$ zfs get all storage/virtualbox|grep dedup storage/virtualbox dedup on local peo at opensolaris-fs:~$ zfs get all storage/testshare|grep dedup storage/testshare dedup on local zfs list shows a dedup value of 2.22x, mainly because I made a few copies of my vdi files in the ''virtualbox'' file system. For what I understand, this value represents the dedup efficiency for the whole zpool. For my ''testshare'' file system, the dedup value should be about 6x, since I just made five copies of a folder with a few hundred files. The question is: is there any way to check/confirm the level of dedup efficiency ? /PeO
On 08/05/2010 21:45, P-O Yliniemi wrote:> I have noticed that dedup is discussed a lot in this list right now.. > > Starting to experiment with dedup=on, I feel it would be interesting in > knowing exactly how efficient dedup is. The problem is that I''ve found > no way of checking this per file system. I have turned dedup on for a > few file systems to try it out:You can''t because dedup is per pool not per filesystem. Each file system gets to choose if it is opting in to the pool wide dedup. -- Darren J Moffat
Darren J Moffat skrev 2010-05-10 10:58:> On 08/05/2010 21:45, P-O Yliniemi wrote: >> I have noticed that dedup is discussed a lot in this list right now.. >> >> Starting to experiment with dedup=on, I feel it would be interesting in >> knowing exactly how efficient dedup is. The problem is that I''ve found >> no way of checking this per file system. I have turned dedup on for a >> few file systems to try it out: > > You can''t because dedup is per pool not per filesystem. Each file > system gets to choose if it is opting in to the pool wide dedup. >So dedup is operating on the pool level rather than the file system level, so if I have two file systems with dedup=on, they share the blocks and checksums pool wide ?
On 10/05/2010 13:35, P-O Yliniemi wrote:> Darren J Moffat skrev 2010-05-10 10:58: >> On 08/05/2010 21:45, P-O Yliniemi wrote: >>> I have noticed that dedup is discussed a lot in this list right now.. >>> >>> Starting to experiment with dedup=on, I feel it would be interesting in >>> knowing exactly how efficient dedup is. The problem is that I''ve found >>> no way of checking this per file system. I have turned dedup on for a >>> few file systems to try it out: >> >> You can''t because dedup is per pool not per filesystem. Each file >> system gets to choose if it is opting in to the pool wide dedup. >> > So dedup is operating on the pool level rather than the file system > level, so if I have two file systems with dedup=on, they share the > blocks and checksums pool wide ?Correct. -- Darren J Moffat