HAST + ZFS + NFS + CARP

[Jordan Hubbard]

> On Jul 3, 2016, at 11:05 PM, Ben RUBSON <ben.rubson at gmail.com> wrote:
> 
> Of course Jordan, in this topic, we (well at least me :) make the following assumption :
> one iSCSI target/disk = one real physical disk (a SAS disk, a SSD disk...), from a server having its own JBOD, no RAID adapter or whatever, just what ZFS likes !

I certainly wouldn’t make that assumption.  Once you allow iSCSI to be the back-end in any solution, end-users will avail themselves of the flexibility to also export arbitrary or synthetic devices (like zvols / RAID devices) as “disks”.  You can’t stop them from doing so, so you might as well incorporate that scenario into your design.  Even if you could somehow enforce the 1:1 mapping of LUN to disk, iSCSI itself is still going to impose a serialization / performance / reporting (iSCSI LUNs don’t report SMART status) penalty that removes a lot of the advantages of having direct physical access to the media, so one might also ask what you’re gaining by imposing those restrictions.

- Jordan