RE: [Xen-users] iSCSI and LVM

["Jonathan Tripathy" <jonnyt@xxxxxxxxxxx>]

 

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From: JP P [mailto:storm66@xxxxxxxxxxxxxxxx]
Sent: Mon 14/06/2010 16:09
To: Jonathan Tripathy
Cc: Xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] iSCSI and LVM

Le lundi 14 juin 2010 à 14:29 +0100, Jonathan Tripathy a écrit :
> Hi Everyone,
> 
> I am going to get a storage server which will be connected to my Xen
> hosts via iSCSI/Ethernet. I wish to use LVM for the DomU disks. The
> storage server will have a RAID10 array, and 2 Xen hosts will connect
> to this (Each will have a 50% share of the RAID10 array, space wise).
> 
> What is the best way to go about this? Should I:
> 
> a) Split the RAID10 array into 2 partition on the storage server, and
> export 1 partition to each xen host, then let the Xen host manage LVM?
> 
> or
> 
> b) Do all LVM stuff on the storage server and export each LVM logical
> volume to the correct Xen hosts via iSCSI? Since each host could have
> around 100 VMs on it, that's a lot of iSCSI exporting!
> 

Hello,

If you export two "big luns" and do the LVM stuff on each Xens server
you will not be able to "switch" a VM from one server to the other (with
xm save/restore for example). With that setup a VM can only be started
on a specific server. Also you will have two LVM sets to manage.

If you do all the storage management on your SAN migrate a VM from one
server to the other will be easy and even done "live". Also the storage
management will be "unified". The only problem could be the maximum
number of iSCSI Luns on yours SAN, but it often is greater than 127
distinct units.

Regards

JPP

----------------------------------------------------------------------------------

Ok thanks for the advice. So I think I shall go down the root of doing all LVM stuff on the SAN.

However, I think that I will need more than 127 virtual machines, so having an iSCSI target per VM is probably not an option. Is there any other solution for Ubuntu/Debian?

 

Thanks

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