Calculating Available Space

[SoonerLater]

How much space do I have available? Is it 1 tb out of 4.4 tb? Or 599 gb out of 2.9? I'm confused.

 

[danb35]

You have 599.9 GiB available out of (2.9 + 0.6) 3.5 TiB.

 

[danb35]

BTW, I've lost count of how many times I've seen this issue posted, so I've filed a bug against the docs: https://bugs.freenas.org/issues/12968

 

[SoonerLater]

You have 599.9 GiB available out of (2.9 + 0.6) 3.5 TiB.

My six physical 1 tb disks are dedicated to a pool which has 4.4 tb of usable space. Since the OS sits on a USB thumb drive, then I would assume that 100% of the RAID space (4.4 tb) is available for data storage. So what has happened with the other 4.4 - 2.9 = 1.5 tb?

 

[danb35]

Can you post a screenshot of your volume status screen? From the page you posted, click on the button at the bottom that looks like a sheet of notebook paper.

 

[Bidule0hm]

It's actually explained in the FAQ: https://forums.freenas.org/index.php?threads/the-faq.30209/#post-194030 ;)

 

[SoonerLater]

 

[danb35]

There's your answer. You have a RAIDZ2 volume, which means two disks' worth of parity. About 3.6 TiB of net capacity is what you should be seeing, and 3.5 TiB is what you have. You're good.

 

[SoonerLater]

There's your answer. You have a RAIDZ2 volume, which means two disks' worth of parity. About 3.6 TiB of net capacity is what you should be seeing, and 3.5 TiB is what you have. You're good.

OK...

6 x 1 tb = 6 tb = raw space before being placed in RAID

4.4 tb = size of RAID, so shouldn't 6.0 - 4.4 = 1.6 tb = the amount lost to parity?

 

[danb35]

No, the size of the RAID is not 4.4 TiB. You need to add the Used and the Available figures. Raw space is 5.4 TiB (which is correct for 6 x 1 TB disks). Similarly, for the net space, you'd add 2.9 TiB and 600 GiB, as I did in my first post, yielding 3.5 TiB. Parity would be two disks' worth, or 1.8 TiB, and the remainder would be filesystem overhead reserved space, etc.

 

[SoonerLater]

Time to do some pruning on this box and to start building another FreeNAS box.

 

[danb35]

...or replace your disks with larger ones, one at a time. You can expand your pool that way without disruption or data loss. Or (if you have room) add a second six-disk vdev and expand your pool that way.

 

[SoonerLater]

...or replace your disks with larger ones, one at a time. You can expand your pool that way without disruption or data loss. Or (if you have room) add a second six-disk vdev and expand your pool that way.

Hmmm.... I had forgotten about the possibility of increasing the size of the existing array by swapping disks, one-at-a-time. It would probably take a week, changing one disk a day for 6 straight days. And this array will be 3 years old in April, so it'll be time to replace those drives anyway....

And I suppose... in theory... if someone made a powered 6 (or more) drive enclosure that could be run from my existing HP N40L server, then I could have a second pool running on the same server.

 

[danb35]

Yeah, an N40L will definitely be full with 6 drives. Replacing the disks one at a time is definitely an option (if you like living on the edge, you could probably do two at a time since your array is RAIDZ2, but I wouldn't recommend it). You could expand your pool using an external storage shelf like this one--holds up to 45 drives. Just need a SAS HBA in your server to talk to it.

Or come over to the dark side (we have cookies) and get a nice 4U, 24-bay rack chassis--that should keep you going for a while...

 

[Ericloewe]

Or come over to the dark side (we have cookies) and get a nice 4U, 24-bay rack chassis--that should keep you going for a while...

It'll be the deaf side if you don't use hearing protection while turning the server on locally. :D

 

[danb35]

I have to confess I haven't used one of the 4U chassis, but my SC826 isn't too noisy when I power it on. My Dell C6100 is another story--that sounds like a jet engine spinning up.