I recently upgraded to FreeNAS 9.1 once it was GA. I have always used compression on the volume that stores all of the virtual machines – instead of using DeDupe which requires considerably more RAM, and doesn’t appear to be as forgiving. That being said, the volume has been configured with LZJB compression and I was seeing about 40-50% compression ratios. Then I converted the volume to LZ4 compression. *Note: Modifying compression only effects new data written to the volume.
After storage vMotioning and copying around all the VMs, I saw an additional 9-10% improvement in compression – here’s some numbers:
- 13.98 GB vmdk with lzjb = 12.61 GB vmdk with LZ4
- 23.32 GB vmdk with lzjb = 20.77 GB vmdk with LZ4
All in all, I was able to reclaim about 20GB of space from compression.