Mirrored iSCSI Targets On Other Machines

[Programming Machine]

Does FreeNAS support mirroring iSCSI targets on other machines (instead of hard disks on the same machine)?
Is it recommended?

 

[jgreco]

I get a funny feeling when you say that.

What do you mean by "mirroring"?

You can certainly mount an iSCSI target on multiple remote machines.

However, that does not mean that any magic is created. People will often try to mount an NTFS iSCSI volume on one machine, put some files on it, then simultaneously mount it on another machine, hoping to "share" the iSCSI volume. That doesn't work. iSCSI happily allows both machines to access the same disk, and does so correctly, but NTFS doesn't have any sort of mechanism to "share" a disk in that manner. It requires what's called a cluster-aware filesystem.

For those of us using systems like VMware's VMFS, though, yes, we routinely mount the same iSCSI volume on several hosts and the hosts use them simultaneously. Because VMFS is a cluster-aware filesystem and is designed to do that.

 

[Programming Machine]

No, that's not what I'm trying to do. I want to run a share on one Freenas file server that is backed by a pair of mirrored iSCSI disks on two other NAS/servers/devices/black boxes.
Or to put it another way: One can make a RAID1 from two local hard disks - can I replace the hard disks with two iSCSI 'disks' (connected over a network cable - not locally)?

 

[jgreco]

I'm going to say no.

You can't do it, at least not via the GUI.

You can probably do a hatchet job at the CLI to make it happen, but it strikes me as a particularly bad idea for approximately all the same reasons we tell people not to use USB hard drives for data disks.