Shrink zvol

volsize zvol vm

Source

• https://forums.truenas.com/t/how-to-shrink-zvol-used-in-iscsi-via-cli/3306/6

• make sure that e.g., a VM using this zvol has properly shrunken its partitions and moved all data to the “logical start” of the device
• also ensure that the new zvol size is a bit (couple of MB or 1 GB) larger than the size of the VM’s partitions to prevent data loss

zfs set volsize=32G poolname/zvolname