SOLVED Question about available space

[mastercpt]

I just decided to redo my freenas server. I now have 8x4TB WD Red drives. When I created a new volume I selected RaidZ1 and gave it all 8 disks. Below is what my storage looks like. I feel like I am missing storage. According to the calculator I found on another post, I think I should have 25.47TiB

Here is what the volume status lists. Should that be in 2 raidz or just 1?

 

[Ericloewe]

You have two RAIDZ1 vdevs, which is quite a useless configuration. Sure, you get more IOPS than with a single RAIDZ2 vdev, but error tolerance is much reduced and storage is the same.

The storage you're getting is spot on with what would be expected.

 

[mastercpt]

You have two RAIDZ1 vdevs, which is quite a useless configuration.

Thanks for reply. That is exactly what I was thinking as well. Didn't know why I had 2 RaidZ1 vdevs. It just auto went to that when I added the available disks. Just tried to recreate it and noticed I can drag the slide up so it is now 8x1x4TB. No it is showing the 25.46TiB I should be expected.

 

[Ericloewe]

I should point out that a RAIDZ1 vdev with 8 4TB drives is strongly discouraged due to the likelihood of data loss.

 

[mastercpt]

I should point out that a RAIDZ1 vdev with 8 4TB drives is strongly discouraged due to the likelihood of data loss.

The drives will be just for TV and Movies which will also be backed up to amazon cloud. But can you explain a bit more on the likelihood of data loss?

 

[Ericloewe]

The matter has been discussed in detail, but this is the tl;dr:
RAIDZ rebuilds take nontrivial amounts of time to finish, which opens up the possibility of additional failures occurring during said resilver. Those failures would be uncorrectable, whereas RAIDZ2 would not be affected by an additional failure. You might say "but the same holds for RAIDZ2 and two drive failures", the answer to that being that no properly-managed array is likely to encounter such a scenario and that RAIDZ3 is available for those who want an even more remote likelihood of data loss.

 

[mastercpt]

Thank you. I appreciate all the information. Will read up more on what you discussed.

 

[Kevin Horton]

Your current setup uses approximately two drives worth of space for parity data, but only has one drive of redundancy. You should consider using all drives in a single RAIDZ2 vdev, which would also be using approximately two drives worth of space for parity, but now has two drive redundancy. Performance may be slightly less, but is likely still completely acceptable.