[zfs-discuss] Compression not work with zfs blocksize=4K and zpool ashift=12

Markus Koeberl markus.koeberl at tugraz.at
Fri Sep 11 06:54:43 EDT 2015

On Friday 11 September 2015 13:26:39 Вадим Сурков via zfs-discuss wrote:
> I have two pools: main and backup.
> Main pool with ashift=9 hosts VM's and has zvol blocksize=4k
> compression=lz4.
> Backup pool with ashift=12 used to store backup increment copies of VM's

I think with ashift=12 and blocksize=4k you can only benefit from 
compression=lz4 if you only write zeros. Otherwise you will always write 4k 
because this is the minimal block size of the disk defined by ashift=12.

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