way for failover zpool (no HAST needed)

[Rumen Telbizov]

Hi Denny,

Although I haven't fully implemented this yet I was thinking of a failover
system
based on carp + ifstated (/usr/ports/net/ifstated).

ifstated will allow you to execute stuff on events like the carp interface
becoming the master/backup.

As a side note I'd suggest that you consider using something like IPMI
to shutdown power on the remote node when you take over/import the zpool.
At least this was my biggest fear - getting into a splitbrain and both nodes
using the pool. I was even thinking of telneting to the APC PDUs and
shutting down ports ;)

Anyway I hope this is a useful idea.
Very interested of what others have done to implement a redundant/failover
ZFS solution.

Cheers,
Rumen Telbizov

On Tue, Mar 29, 2011 at 4:17 AM, Denny Schierz <linuxmail at 4lin.net> wrote:

> hi,
>
> my two nodes are running fine with 8.2-stable and the LSI 9200-8e and
> now, I want to build a failover for the Zpool (and later ISCSI target)
>
> Both nodes are connected to the same disks (jbod) and now I need a way,
> to get the zpool(s) running on the node with the CARP public IP.
>
> I found something about carp, hooks, devd etc. pp. My first thought was:
>
> carp -> hook -> zpool import -> devd -> ISCSI target up
>
> Problem HostA: no network:
>
> carp -> hook -> zpool export -> devd -> ISCSI target down -> OK
>
> Back to master shouldn't be a problem, I think ...
>
>
> Problem HostA: power off:
>
> carp -> hook -> zpool import -> devd -> ISCSI target up -> OK
>
> But a bad problem could be:
>
> Problem HostA: SAS Cntrl/cabel problem:
>
> carp is up and running ..., no reason to failover to slave ... -> bad
>
> So, I mean, I have to use devd who takes notes, that the /dev/da* disks
> are gone or inaccessible and inform carp or shutdown the network
> interface to force carp switching over to slave.
>
> So any hints are welcome :-)
>
> If it works, I will write a howto for that one :-)
>
> cu denny
>
>
>


-- 
Rumen Telbizov
http://telbizov.com