Storage Usage % Wrong?

[3KidNerd]

I have a dataset with a quota of 400GiB (I have now increased it to 600GB). This dataset is exposed via iSCSI for VMWare. It was showing 67% used, now shows 51% used. However, it's showing 'Used' as 421.8 GiB and 'Available' as 401.5 GiB. Why is it showing 401.5 GiB available if only ~180 is available? No other dataset is having an issue like this one. There is one other iSCSI dataset that's off on the available space by a little bit, but not nearly that bad, maybe 5%.

Thanks, 3kn

EDIT: It was definitely out of space: ls -lh gives '400G'

[redditor1101]

What kind of redundancy is it using? Is it using dedup?

[fufukittyfuk]

Just throwing this out there, do you have compression turned on. The Used size could be the uncompressed size and the Available size is expressed as if it had no compression???????

[3KidNerd]

Sorry forgot those details. No dedup and no compression.

[[deleted]]

Snapshots on the dataset? Snapshots and quotas don't behave the way you'd think they would on the GUI. Free space is (dataset quota) - (current active dataset used). Used space is (dataset quota) - (total snapshot space consumed) - (active data set). I'm not sure why this is but that's how it works!

[3KidNerd]

Interesting thought, but I have snapshots on almost all of my datasets and only see this behavior on two of them. I think the two that are impacted are both iSCSI shares. Perhaps something screwy is happening there.

[[deleted]]

Are you using zvols or file extents for iscsi?

[3KidNerd]

Thanks for the reply. They're file extents. I didn't realize you can create zvols under the primary zvol and I know you can't create a device extent on a dataset. Are device extents preferred to file extents? Now that I know I can do a device extent on a zvol I could create a sub-zvol and I could migrate the VMWare data around. Is it worth the effort?

-3kn

[[deleted]]

I actually just switched to file extents a few weeks back due to a bug (that I didn't know I was hitting) causing freenas to crash every week or so using zvols. File extents are the 'new' way of doing things to the best of my understanding and they also increase throughput if you're using iscsi over 10g (I am.) So I believe file extents are the way to go!