ZFS Compression and windows disk compression via iScsi

[Alphonso]

Is it a bad idea to be using windows disk compression with freenas iscsi if I already have ZFS compression enabled? I'm using the volume for file backups so I should be getting quite a bit of benefit using some sort of compression. Im using UrBackup and the manual recommended to enable compression on the backup folder.

Im using v9.2.1.8 with the experimental iScsi features enabled. (Seems to be properly unmapping deleted files on the freenas side now :D)

 

[mav@]

Initiator side compression is probably only question of the initiator. It should save you some network bandwidth, and may improve performance if network is a bottleneck and compression is fast enough for the initiator's CPU. Also it should give you better disk space usage accounting on the initiator side.

For FreeNAS it should be irrelevant. Its compression will detect incompressible data and write them as-is. Except some CPU usage to detect that, there should be no ill effects. If you are sure that initiator does compression well, you may completely disable compression for the volume on FreeNAS side to save some CPU time.

 

[cyberjock]

I wouldn't use NTFS compression with iSCSI unless you expect to get amazing compression ratios with it and expect to be bottlenecked by network throughput (which almost nobody is). For a more thorough understanding of why I say this you would need to read up on NTFS compression and how it works. ;)

 

[Ericloewe]

Basically, NTFS compression uses old algorithms (FreeNAS's default is quite newer) that have trouble with large files and contribute to fragmentation (the last thing ZFS needs more of). It'll probably have worse gains than LZ4 running on FreeNAS, as well.