[Dovecot] mdbox compression

[Damon Atkins]

ZFS has support for compression on the file system ( lzjb | gzip | 
gzip-N | zle ). gzip eats CPU even at levels as low as 3.

 From the zfs man page
The lzjb compression algorithm is optimized for performance while  
providing  decent  data  compression. You can specify the gzip level by 
using the  value  gzip-N  where  N  is  an integer  from 1 (fastest) to 
9 (best compression ratio).

The cost of CPU to support compression (gzip) vs the Cost of Disk if 
mboxes are not compressed?

The other interesting feature ZFS (OpenSolaris) has is de-duplication, 
it detects if the block which is about to be written, is the same as 
another block and instead of writing the block it puts a pointer to the 
already existing block, saving disk space. Only problem with this is you 
would need to filter out headers which are different even when the 
to/body is the same.

Cheers