Re: ZFS on a shared iSCSI

On Wed, Feb 7, 2024 at 12:25 PM Ben RUBSON <ben.rubson@gmx.com> wrote:

> > On 7 Feb 2024, at 11:55, Andrea Brancatelli <andrea@brancatelli.it>
> wrote:
> >
> > Would it be "easily possible" to have some (2?) iSCSI LUN exposed to
> both servers and then activate the pool on one or the other server?
>
> Hi Andrea,
>
> Yes, I have such configurations :
> 2 servers with same JBODs configuration.
> When zpool is mounted on server A, mirroring is done on both local disks
> and iSCSI disks from server B.
> When zpool is mounted on server B, mirroring is done on both local disks
> and iSCSI disks from server A.
> Works flawlessly.
> And you can have one of the 2 servers offline for some time, when it will
> be back online, sync will restart.
> What you can't have is zpool online on both servers at the same time.
>
> So you can do the same with iSCSI disks only.
> Disks will have to be mounted on one server at a time only.
>
> You'll have to have a rather low network / iSCSI latency, or it will fail
> / zpool will be unusable.
> If you have high latency, you'll have to go for ZFS send/receive.
>

That sounds like an interesting setup, although we have an external iSCSI
"SAN" so the iSCSI approach would be totally offloaded, without any local
storage.

Imagine Server A having a certain LUN on the iSCSI device and Server B
having another one.

If a server fails, the idea would be to activate the pool "on the fly" on
the other one.

Otherwise I totally take iSCSI out of the picture (less is better), have
local disks and zfs-snapshot stuff back and forth.





-- 
*Andrea Brancatelli*