[Linux-cluster] Linux Cluster + KVM + LVM2

Wed Jul 20 09:40:10 UTC 2011

Hi,

thanks for your answer.

On 20 July 2011 09:06, <Ralph.Grothe at itdz-berlin.de> wrote:

> Hi Marc,
>
>
> though Digimer's RHCS tutorial is an excellent introducion to the
> RHCS cluster with a thourough step by step reference to setting
> up a Xen cluster, and I'd highly recommend you read it, you
> probably also would like to have look at these articles in the
> cluster wiki which focus a little more condensed on your
> questions.
>
> Here is described how to set up so called HA-LVM which avoids the
> clmvd overhead and is for settings like yours where you only
> require active/passive VG activation (i.e. a shared storage VG is
> only activated on a single cluster node at any time).
> This is achieved by tagging of the affected VGs/LVs.
>
> https://fedorahosted.org/cluster/wiki/LVMFailover
>
> Unfortunately, this article lacks mentioning of the required
> locking_type setting in lvm.conf.
>
> But if you have access to RHN this article on HA-LVM does, and it
> also outlines both methods, i.e. the so called "preferred clvmd"
> method and the so called "original" (or what I'd call "tagging")
> method which doesn't require clvmd:
>
> https://access.redhat.com/kb/docs/DOC-3068
>
>
> Should you on the other hand require active/active VGs (i.e.
> simultaneous activation of the same shared VG on more than one
> cluster node), which I consider not a requirement for a KVM
> cluster (but I lack any experience in this field) the recommended
> procedure is described here:
>
> https://access.redhat.com/kb/docs/DOC-17651
>

Great links, this is what we were looking for. We'll try this before testing
GFS2 because we are preferably want to work directly over Logical Volumes.

Thanks a lot for your reply,
Marc

>
>
> Important aside, after you've edited the lvm.conf you are
> required to make a new initial ramdisk (or at least touch the
> mtime of the current initrd) or cluster services won't start on
> that node (watch entries in messages or whereever syslogd logs
> clulog stuff to).
>
>
>
> In this article you may find something treating KVM VMs'
> migration.
>
> https://fedorahosted.org/cluster/wiki/KvmMigration

>
>
> Regards
> Ralph
> (an RHCS newbie himself)
> ________________________________
>
>        From: linux-cluster-bounces at redhat.com
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Marc
> Caubet
>        Sent: Tuesday, July 19, 2011 4:19 PM
>        To: linux-cluster at redhat.com
>        Subject: [Linux-cluster] Linux Cluster + KVM + LVM2
>
>
>        Hi,
>
>        we are testing RedHat Cluster to build a KVM
> virtualization infrastructure. This is the first time we use the
> Linux Cluster so we are a little bit lost. Hope someone can help.
>
>        Actually we have 2 hypervisors connected via Fiber
> Channel to a shared storage (both servers see the same 15TB
> device /dev/mapper/mpathb).
>
>        Our idea is a shared storage to hold KVM virtual machines
> by using LVM2. Both server should be able to run Virtual Machines
> from the same storage, but we should be able to migrate or start
> virtual machines on the other server node on crash.
>
>        So the plan is:
>
>        - Virtual Machine image = Logical Volume
>        - CLVM2 cluster: only one server node at the same time
> will be able to manage the volume group-
>        - KVM Virtual Machine High Availability. Machines will
> run on one server node. If for some reason the server node
> crashes, the second will start / migrate the virtual machine.
>
>        Basically we woul like to know:
>
>        - How can we create a cluster for the LVM2 shared storage
> (when we create it, it does not work since both server nodes have
> the VG as Active)
>        - How can we create a cluster service for a virtual
> machine (we guess it has to be done 1 by 1)
>        - Since we have 2 server nodes, how to increase the
> number of votes for quorum (qdisk over a heartbeat logical volume
> partition?)
>
>        Thanks and best regards,
>        --
>        Marc Caubet Serrabou
>        PIC (Port d'Informació Científica)
>        Campus UAB, Edificio D
>        E-08193 Bellaterra, Barcelona
>        Tel: +34 93 581 33 22
>        Fax: +34 93 581 41 10
>        http://www.pic.es
>        Avis - Aviso - Legal Notice:
> http://www.ifae.es/legal.html
>
>
>
> --
> Linux-cluster mailing list
> Linux-cluster at redhat.com
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>

-- 
Marc Caubet Serrabou
PIC (Port d'Informació Científica)
Campus UAB, Edificio D
E-08193 Bellaterra, Barcelona
Tel: +34 93 581 33 22
Fax: +34 93 581 41 10
http://www.pic.es
Avis - Aviso - Legal Notice: http://www.ifae.es/legal.html
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