HAST, zfs and local mirroring

[Slawa Olhovchenkov]

On Fri, Jun 03, 2016 at 01:40:54PM +0500, Eugene M. Zheganin wrote:

> Hi.
> 
> On 02.06.16 19:50, Slawa Olhovchenkov wrote:
> > I am suggesting next setup:
> >
> > node0:
> >   own pool zroot0: mirror-0: local_disk0
> >       	   	   	     remote-iscsi_disk1/1
> >   local_disk1: exported by iscsi as remote-iscsi_disk0/1 to node1
> >
> > node1:
> >   own pool zroot1: mirror-0: local_disk0
> >       	   	   	     remote-iscsi_disk0/1
> >   local_disk1: exported by iscsi as remote-iscsi_disk1/1 to node0
> >
> >
> > No HAST.
> > Disks synced by ZFS over iSCSI.
> But this way I will get two independent zfs pools (or I still didn't get
> it), one half of each will be stored on another machine.

Yes.

> And I need
> something different - a continuously replicated disk resource, that
> would be available on both machines in case either will crash.

I think this is imposible.
All modern FS (cluster also) believe exclusive modifivation of on-disk
data. Cluster FS just acts as services (but still believe exclusive
access to HDD)


> Cluster
> filesystem would be fine, but as far as I know there's no such thing on
> FreeBSD, so I accept it will be unavailable on slave while mounted as
> read-write on the master. HAST looks like a thing thats fits my
> requirement, only that I wank it to be redundant inside each host too,
> and all the documentation shows examples without local redundancy.

You can't touch local HDD HASTed to remote.