Re: EVMS or Cluster LVM

I use:
- plain LVM 
- + heartbeat
- + normal file system (reiserfs)

and it works pretty well, after a few modifications to the LVM script (to 
make sure that when cluster switchover, LVM release disk groups).

An idea is that you can use usual LVM, but cluster must maintain it 
mounted on the single host only. So I can modify LVM group without any 
problems and can switchover group to another server (and I can configure a 
few resources in heartbeat so that by defaulkt they spread over 2 
servers).

I really DON'T RECOMMEND running any VM (Vmware or XEN, dont make any 
difference) on OCFSv2 (it's curious but OCFSv1 was suited for VM 
hosting much better) -  OCFSv2 makes too many resource locks and XEN (or 
VMWare) can't lock disk image on the single node when VM guest is alive,
so it cause a huge extra load of the OCFSv2 and wil work very slow.

You can try non-clustered LVM for the clustered data too, but (as was 
saying earlier) you must be sure, that when you change LVM layout, disk 
group is mounted (I mean vgscan groups) on the single node only.

Alex Roudnev
Exigen Group 
415 806 3741





"Ciro Iriarte" <[email protected]> 
Sent by: [email protected]
06/06/2008 05:02 PM

To
"Olivier BOYAVAL" <[email protected]>
cc
[email protected]
Subject
Re: [suse-sles-e] EVMS or Cluster LVM






2008/6/6 Olivier BOYAVAL <[email protected]>:
>  Hi,
>
> I want to create a farm Xen server on a SAN. I don't want to work with 
disk
> file for DomU and I would like to use LVM to manage partition on the 
LUN.
>
> LVM isn't cluster aware and Novell docs tell us to use EVMS instead.
>
> But EVMS is depreciated, no update since 2006 and IBM discontinued
> development of this project.
>
> I found some web page on CLVM but SLES LVM2 isn't compiled with it.
>
> Any ideas to make this farm server other than using ocsf2 ?
>
> --
> Olivier Boyaval
> Direction du Système d'Information Hospitalier
> Responsable équipe maîtrise d'oeuvre informatique
> Tél : 03.21.64.42.20
> Fax : 03.21.64.44.38

I'm seeing i/o wait of about 100% with file disk images on OCFS2 and I
agree it's not a good idea... I'm going with a LUN per domU as i'm not
going to run too many of them, if you're the SAN admin or you can nag
him frequently, it's a good route.

Another option is to use plain LVM, the only catch is that when you
need to modify metadata (resize, new volume creation), only one node
can be online.

Regards,

Ciro
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