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Re: OT: Re: [Xen-users] Re: multiple iscsi targets on bonding interface

To: Jeff Williams <jeffw@xxxxxxxxxxxxxx>
Subject: Re: OT: Re: [Xen-users] Re: multiple iscsi targets on bonding interface
From: Christopher Chen <muffaleta@xxxxxxxxx>
Date: Tue, 5 May 2009 22:22:28 -0700
Cc: Ferenc Wagner <wferi@xxxxxxx>, Xen mailinglist <xen-users@xxxxxxxxxxxxxxxxxxx>
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My first stab about it involved setting up cLVM across a Centos/RH
Cluster with rgmanager handling the DomU provisioning. It all works,
but that means LVM gets put in the sandwich at least three times--a
bit much.

My idea for next time is to use dm-multipath on the Dom0 that uses
friendly names associated with scsiSN set on IET on the
target--namely, I provision a lun on the target, give it a unique
scsiSN, then with dm-multipath friendly name mapping, I associate that
scsiSN with, for instance, /dev/mpath/target.guest.root for whatever
you want, that way I can refer to the friendly names in my DomU
configs and all I have to do is manage a single list that gets
propagated via cfengine or whatever.

My 2c.


On Tue, May 5, 2009 at 7:35 PM, Jeff Williams <jeffw@xxxxxxxxxxxxxx> wrote:
> On 10/04/09 23:16, Ferenc Wagner wrote:
>> Don't confuse the different layers.  Each of our PV domUs are backed
>> by independent iSCSI targets, to make independent live migration of
>> domUs possible.  Each domU sees its assigned target as virtual disk
>> /dev/xvda, and has no idea whatsoever that it is an iSCSI target in
>> reality.  Then each domU uses this virtual disk as it wants: some
>> partition it, some use it as an LVM physical volume, some put a
>> filesystem straight on it.  iSCSI is absolutely out of the picture
>> here, with the exception of the iSCSI rooted domUs, which, on the
>> other hand, have no disk devices assigned to them by Xen: they are
>> (virtual) "diskless"; the Xen host doesn't know they mount iSCSI
>> devices as their roots from initramfs.
> Ferenc,
> Just out of interest, do have any problems managing all of those iSCSI
> targets across all of your Xen dom0s? I would imagine you'd end up with a
> very large number of /dev/sd* devices on all of the dom0s?
> Regards,
> Jeff
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-users

Chris Chen <muffaleta@xxxxxxxxx>
"I want the kind of six pack you can't drink."
-- Micah

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