zvol quotas

[rwfitzy]

Perhaps someone can help me understand zvol quotas better. I have a set of zvol volumes under a dataset with a quota of 765GB for the dataset. Inside the dataset, there are 6 zvol, each with a quota of 150GB. I realize the total quota for the dataset is lower than the total of zvol sizes. I really wanted to see how all worked and I planned to move those zvols to another user dataset once I do understand.

Each zvol is used for backup on a Windows machine mounted via iSCSI and formatted 150GB NTFS. After a week, one of the zvol runs out of disk space with an alert from netdata and shows 157.9GB used under the Storage pool. Inside the operating system, I see free space of 31.2GB on the 149GB drive size. There are no snapshots for this dataset. Also, there is no quota showing with zfs get:

Code:

NAME                              PROPERTY         VALUE     SOURCE
Backup/iscsi/sp-steph  used             158G      -
Backup/iscsi/sp-steph  available        150G      -
Backup/iscsi/sp-steph  referenced       158G      -
Backup/iscsi/sp-steph  quota            -         -
Backup/iscsi/sp-steph  usedbysnapshots  0         -
Backup/iscsi/sp-steph  usedbydataset    158G      -
Backup/iscsi/sp-steph  written          158G      -
Backup/iscsi/sp-steph  logicalused      119G      -
--------------------------------------------------

I guess there is no quota set even though the size of the zvol is set to 150GiB. Can a quota be set and why would this zvol show 157.9 used disk space?

I did find this post: https://serverfault.com/questions/512018/strange-zfs-disk-space-usage-report-for-a-zvol
This server is using RAIDZ2 with 5 2TB disk drives, 2.1TB free space. The drives are Seagate Constellation with I believe 512 sector size. I chose the default block size and that appears to have been 16K.

 

[dlavigne]

Were you able to figure this out?

 

[rwfitzy]

No, very strange. I have five of these 150 GB zvol volumes under the same dataset. All the other four show 152.5 GB used in the GUI, this one now showing 189.2 GB used. No snapshots have been taken.