Mounting ZFS media

[John M. Długosz]

Normally, I expect to be able to mount a file system present on some partition of some drive that's been inserted. I assume it would be the same for a partition containing ZFS, but...

First, I know that ZFS in general allows partitions, the GUI for FreeNAS only knows whole drives, as far as the instructions I've read shows. Can this be done?

Second, what is the deal with multiple drives in a set? If I insert, say, three drives that contain a zpool, does it figure it all out by itself? With traditional RAIDs, I have to be sure to get the drives in the same order and specify the RAID details.

 

[dlavigne]

ZFS prefers to be fed whole drives, not partitions.

The ZFS info is written to the disk itself, so yes, it will figure out itself the layout of the pool and will complain if a disk becomes unavailable.

 

[John M. Długosz]

The stuff I've read stated that whole disks (not partitions) is because the real-for-sure flushing might not work on a partition. But maybe it does now. IAC, it would be for making offline copies not production use, so the dataset or whatever files can be copied and then checked before ejecting and storing the media. If the power went out during that operation, I'd start over just to be sure, anyway.

—John

 

[cyberjock]

ZFS prefers to be fed whole drives, not partitions.

The ZFS info is written to the disk itself, so yes, it will figure out itself the layout of the pool and will complain if a disk becomes unavailable.

ZFS uses partitions now. In fact, that's how FreeNAS sets up zpools by default. :)

 

[paleoN]

The stuff I've read stated that whole disks (not partitions) is because the real-for-sure flushing might not work on a partition.

Actually, this has never been true for FreeBSD. It is true for Solaris based distros. FreeNAS GUI uses whole disks to setup ZFS which it proceeds to partition for you on the backend.

AFAIR, the GUI had issues importing multiple partitions from a single disk. That person may have been using UFS though.