zpool total/available space

[rumdr19]

I am trying to figure out why my space available seems off. According to my calculations I should have around 16TB available. However, ZFS is only reporting 13.1TB. Here is my configuration for this pool:

6x 4TB drives

Code:

 Mediapool                                       ONLINE       0     0     0
          raidz1-0                                      ONLINE       0     0     0
            gptid/af8f771b-beaf-11e4-9139-0015178a488c  ONLINE       0     0     0
            gptid/b0783da7-beaf-11e4-9139-0015178a488c  ONLINE       0     0     0
            gptid/b15bfe32-beaf-11e4-9139-0015178a488c  ONLINE       0     0     0
          raidz1-1                                      ONLINE       0     0     0
            gptid/95fb2192-add6-11e5-ae88-0015178a488c  ONLINE       0     0     0
            gptid/9736dfb9-add6-11e5-ae88-0015178a488c  ONLINE       0     0     0
            gptid/98614610-add6-11e5-ae88-0015178a488c  ONLINE       0     0     0

Code:

NAME           SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
Mediapool     21.8T  13.1T  8.65T         -    32%    60%  1.00x  ONLINE  /mnt

My SMB share is also reporting 13.8TB. I am not sure if there is anything I am missing here. Any input?

 

[gpsguy]

No, you're not missing anything.

On of the biggest misunderstands is the drive makers use TB whereas FreeNAS and Windows use TiB. With bigger drive sizes the difference is more apparent.

There are a number of threads, asking the same question. Rather than repeat it again, here's one of them - https://forums.freenas.org/index.php?threads/calculating-available-space.40263/#post-252652

 

[adrianwi]

And if you're only just starting out and haven't filled the pool with data, putting all 6 into a single raidz2 vdev might be a better option?

 

[Mr_N]

yeah don't use raidz1 :)

 

[brando56894]

This threw me off before too, it all comes down to the binary to decimal conversion and the space used for parity.

Sent from my Nexus 6 using Tapatalk

 

[DrKK]

Yeah, I concur. While two three-disk vdevs with RAID-Z1 is certainly "acceptable", it is not particularly recommended, especially since a single six-disk RAID-Z2 would offer the same overall parity ratio (33%), and would be slightly more robust in terms of which disks can fail and when (i.e., you can lose two, provided both aren't in the same vdev, versus, you can lose ANY two).

If you haven't started putting data yet on the system, reformatting it as a single, six-disk, RAID-Z2 certainly seems sensible to me, and preferred in 98% of scenarios.