I just got 6 new 2TB drives, and added them to my FreeNAS box. I have only dealt with RAID1 previously, and each setup has given what I was expecting.

However, with the 6*2TB drives, I wanted to maximize the space available, so I went with raidz. But I seem to be missing space. I have 8.6TB available after the raidz was built. Maybe I did my math horribly wrong, but (N-1) x S(min) (where N=6 and S(min)=2TB) should result in 10TB. (I understand it would be more like 9.something)

Does raidz actually consume more then 1 drive worth of space? Or could their possibly be another problem? (All drives have been independently verified that 2TB of space is available)


Freenas/Zfs reserves a small fragment of drive space. So besides having only ~1.82TB of actual space. ZFS reserves 1/64th of drive space for its own means, thus 'stealing' another ~28gb from you on every drive. Also freenas makes a 2gb swap file on every drive, Then losing the 1 drive to Raidz, 8.6TB seems pretty close.

Source: http://cuddletech.com/blog/?p=261

edit Freenas swap file on every drive added.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.