[Linux-cluster] CLVM mirroring state (was Re: 2 Nodes, IDE, no SAN Solution?)

[Ed L Cashin]

Benjamin Marzinski <bmarzins at redhat.com> writes:

...
[Re: each node exports its disks for a "big share"]

> If I'm understanding you correctly, there is no good way that I know of to
> do this now. But we are working on changing that.
>
> right now you can use gnbd or iscsi to export block devices to other nodes.
> (I don't know if there are any software iscsi targets that allow you to also
> use the exported block device locally. gnbd does. The unh-iscsi target might)
> Every node could export a spare partition to all the other nodes. If you had
> N nodes, you would have N block devices, all the same size (1 local, and N-1
> remote).  If you had cluster aware mirroring, you could set up a mirror on
> top of all those devices, and then you would have a consistent image on each
> node.  However, to make this reliable, you can't have "the big share" as you
> called it. If there is information that only exists on one device, It's likely
> that the entire cluster would crash in the event of one machine going down.
>
> As soon as cluster aware mirroring is available (it's being worked on)
> This should be easily doable.

Huh.  I thought that CLVM had mirroring support that works now.  In
fact, I was planning to test it soon.  

I plan to set up a GFS filesystem using CLVM on EtherDrive storage
blades so that the CLVM-supplied mirroring provides redundancy.

-- 
  Ed L Cashin <ecashin at coraid.com>