[Linux-cluster] Clustered LVM for storage

[Xavier Montagutelli]

On Friday 09 March 2012 16:55:36 Jeff Sturm wrote:
> Sure.   As long as you don't try to make use of any LVM features that
> require metadata consistency (mirroring, snapshots, online resizing, etc.)
> you can get by using LVM without clustering.

Yes, particulary using the (relatively new) options of lvchange / vgchange :

--refresh
   If any logical volume in the volume group is active, reload its metadata.  
   This is not necessary in normal operation, but may be use-
   ful if something has gone wrong or if you're doing clustering manually 
   without a clustered lock manager.


> 
> -Jeff
> 
> From: linux-cluster-bounces at redhat.com
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Charles Riley Sent:
> Friday, March 09, 2012 8:56 AM
> To: linux clustering
> Subject: Re: [Linux-cluster] Clustered LVM for storage
> 
> 
> We're talking 36TB of storage here..  I've never had much success
> partitioning an array of that size (and actually being able to use all of
> the space) without lvm.  But I might give that a try.
> 
> Continuing along this line of thought:
> If I stop access to the array from all of the servers before I make any
> changes, I could probably even make use of lvm without clustering.
> 
> Charles
> 
> 
> On Thu, Mar 8, 2012 at 5:59 PM, Jeff Sturm
> <jeff.sturm at eprize.com<mailto:jeff.sturm at eprize.com>> wrote: With aoe you
> can use old-fashioned disk partitioning.  Just run "parted" (or whatever
> partitioning tool you choose) and allocate storage for partitions as you
> see fit.
> 
> The benefits of doing this are:  Easier/simpler to setup than cluster
> suite, and you can still use all the spindles from your aoe target (for
> example by creating a large RAID-10 array across all disks).
> 
> The downside of partitions is they aren't easy to change.  You can add them
> safely while the storage array is in use, but each host needs to reload
> the partition table when you're done with changes before the new storage
> can be used, and that may not happen until you rmmod/modprobe the aoe
> driver, which you can't do while any partitions are in use, e.g. on
> mounted file systems.  And resizing partitions is tricky because they are
> allocated on consecutive sectors.
> 
> So if you want the flexibility of adding/removing/modifying volumes at any
> time, it may be worth the trouble to get Cluster Suite running so you can
> use CLVM.  If you just want to carve it up once and forget about it,
> partitioning the array will be the fastest.
> 
> -Jeff
> 
> From:
> linux-cluster-bounces at redhat.com<mailto:linux-cluster-bounces at redhat.com>
> [mailto:linux-cluster-bounces at redhat.com<mailto:linux-cluster-bounces at redh
> at.com>] On Behalf Of Charles Riley Sent: Thursday, March 08, 2012 1:59 PM
> To: linux cluster
> Subject: [Linux-cluster] Clustered LVM for storage
> 
> Greetings,
> 
> I have an aoe device with a lot of storage in it that I would like to share
> among four rhel 4 servers.  Each of the servers will mount it's own
> storage, no data is shared between them.  e.g the servers won't be
> mounting the same volumes.
> 
> I could create four different raid groups on the aoe device and present a
> different one to each server, but that would waste space. What I'd rather
> do is create one big raid group and use clustered lvm to divvy the space
> between servers.
> 
> Is it possible?  Would it be enough to run just the clustered lvm daemon,
> or would I need to install all of the cluster suite? Are there
> other/better options?
> 
> Thanks!
> 
> Charles
> 
> 
> 
> 
> 
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> 
> 
> --
> Charles Riley | eRAD<http://www.erad.com> | Director of Technical Solutions
> | O: 864.640.8648 C: 864.881.1331

-- 
Xavier Montagutelli
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