Volume size not the same as on setup

[NoHesHere]

Hi all,

I am new to FreeNAS, and just built a NAS from scratch the other day. Everything was/is working perfectly, but this morning I noticed that the size of the Z1 volume I created is reporting as less than it did at initial setup.

I have 7 2TB WD Red drives, in a Z1 array. I created a volume spanning all the disks, and it reported 10.5TB as the available space. I created 3 datasets, each with their own quota's (6TB, 4.3TB, 75GB), and the total does not sum up to more than the 10.5TB I should have. By my calculations, I should have 125GB remaining.

When I logged into the web UI this morning, the 10.5TB volume (not the datasets) reports available space as 8TB (which is about right, from my transferring, though I am not sure if that part should be updating or not), but it also lists the Size (which I take to be the total size, used and unused space) as 8TB. Is this something to worry about? Do I still have 10.5TB to allocate, or do I have space that disappeared somewhere?

 

[jgreco]

ZFS space accounting is confusing and complicated. Don't feel bad if it doesn't make sense. I don't like trying to wrap my head around the numbers sometimes either, but if you experiment a little bit with some 100GB files, you can get a feel for how it all fits together. That's what I do if it doesn't seem to be making sense, then I usually see what it is doing.

 

[panz]

RAID calculator? http://www.servethehome.com/raid-calculator/

 

[jgreco]

No, that's trivial. The problem is that ZFS has to properly account for space available, space allocated, space reserved, and quotas, which is complicated all by itself, but then there's complications like snapshots, compression, deduplication, copies, etc. which make understanding the numbers even more entertaining. Different things report the statistics differently, such as the numbers reported through statfs are a set of numbers that ZFS designers felt were most likely to allow programs to work more-or-less correctly.