Paul Johnston wrote:
> Now we have dedup I fancy having a play and there was an old blog from Eric
> Kustarz among other things it showed how zdb could show the percent that
> could be duped.
> http://blogs.sun.com/erickustarz/entry/how_dedupalicious_is_your_pool
> However the man page for zdb is sparse and frightening.
> Is anyone aware of a tutorial on the subject and no I don't mind if it
> trashes the machine :-)
Dedup has changed how -S option for zdb works... so now you don't have
to calculate yourself how dedupalicious your pool is, 'zdb -S poolname'
does it for you (and you don't even have to turn on dedup on you pool
first!).
Try 'zdb -S poolname' for your pool. I got the following results for my
rpool:
# zdb -S rpool
Simulated DDT histogram:
bucket allocated referenced
______ ______________________________ ______________________________
refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE
------ ------ ----- ----- ----- ------ ----- ----- -----
1 625K 9.9G 7.90G 7.90G 625K 9.9G 7.90G 7.90G
2 9.8K 184M 132M 132M 20.7K 386M 277M 277M
4 1.21K 16.6M 10.8M 10.8M 5.71K 76.9M 48.6M 48.6M
8 395 764K 745K 745K 3.75K 6.90M 6.69M 6.69M
16 125 2.71M 888K 888K 2.60K 54.2M 17.9M 17.9M
32 56 2.10M 750K 750K 2.33K 85.6M 29.8M 29.8M
64 9 22.0K 22.0K 22.0K 778 2.04M 2.04M 2.04M
128 4 6.00K 6.00K 6.00K 594 853K 853K 853K
256 2 8K 8K 8K 711 2.78M 2.78M 2.78M
512 2 4.50K 4.50K 4.50K 1.47K 3.52M 3.52M 3.52M
8K 1 128K 128K 128K 15.9K 1.99G 1.99G 1.99G
16K 2 8K 8K 8K 50.7K 203M 203M 203M
Total 637K 10.1G 8.04G 8.04G 730K 12.7G 10.5G 10.5G
dedup = 1.30, compress = 1.22, copies = 1.00, dedup * compress / copies
= 1.58
regards,
victor
