[Users] host raiding two LUN from different external storage

[Johan Kragsterman]

 Hi!

Of coarse you can use this feature at the SAN level, if you got it. I can do it in my setup, but there are other complications with doing so, as well, as performance issues. Continues/direct/syncronous replication, whatever you want to call it, is a performance demanding operation, and your SAN controllers need to be able to put up with it, as well as your interconnection needs to be good. 

If you use fibre channel, and you got a proper connection, I can see no reason why you shouldn't do it? The difference in latency will be minimal, if you don't have the two DC's too far apart. And if you use LVM for mirroring, the second node(host) will detect the LVM metadata by itself, so you don't have to perform the mirror operation on the second node.

I wouldn't do it with iScsi though, and/or over an interconnection that you don't control yourself.  

A drawback might be, though, that the data is on a logical volume on the host level, and not on the LUN, which means that you need backup on the host level.

Rgrds Johan

-----users-bounces at ovirt.org skrev: -----
Till: Johan Kragsterman <johan.kragsterman at capvert.se>
Från: Dan Yasny 
Sänt av: users-bounces at ovirt.org
Datum: 2012.07.29 12:56
Kopia: users at ovirt.org
Ärende: Re: [Users] host raiding two LUN from different external storage

You can use replicated at the SAN level storage between different DCs, for DR. You can also use Gluster for the same purpose. 

Setting RAID1 between two geographically separate hosts is asking for trouble.


----- Original Message -----
> From: "Johan Kragsterman" <johan.kragsterman at capvert.se>
> To: users at ovirt.org
> Sent: Sunday, 29 July, 2012 12:08:20 PM
> Subject: [Users] host raiding two LUN from different external storage
> 
> Hi!
> 
> In some setups, like when you got two datacenters that works like
> failover sites, you would like to have two external raid
> controllers(storage devices), one in each datacenter.
> 
> You then send two identical LUN's, from each controller, to a
> cluster, let's say two hosts, for simplicity. What you normally do
> is to host raid these LUN's in mirror(raid 1), so the hosts write
> the same to both LUN's, and both controllers.
> 
> Question for me here is if I can accomplish this in oVirt management?
> Because if I can't, it will be a problem, because if I host raid at
> the host level, then the storage would be local storage for oVirt,
> wouldn't it? And then I suppose it can't be used for live migration,
> can it?
> 
>  Regrds Johan
> _______________________________________________
> Users mailing list
> Users at ovirt.org
> http://lists.ovirt.org/mailman/listinfo/users
> 

-- 



Regards, 

Dan Yasny 
Red Hat Israel 
+972 9769 2280
_______________________________________________
Users mailing list
Users at ovirt.org
http://lists.ovirt.org/mailman/listinfo/users