I have a question about XenServer running on a ISCSI SAN

If my XENSERVER dies, would I still be able to purchase a new server, install XENServer and then load up the existing VM's on the new server which are stored on the ISCSI SAN?

(Will it just load? or will it fail? windows key will become invalid?)

  • 1
    Better yet, boot the server from the iSCSI SAN. If the server dies you get a new one, pop the iSCSI card in it and the new server thinks it's the old one and takes off like nothing ever happened. – Chris S Apr 28 '11 at 17:46

Yes, as long as you have a backup of the metadata. "Metadata" stores the name, RAM size, and attached disks for each VM. Without the metadata, all you have is a collection of VHD disk images with no names, and virtual machines!!!! If you lose your metadata, you don't lose any of your data, but you must manually piece together each vm, and which drives went with it. What a pain!!

Here's how to configure backups so this doesn't happen to you:

You will need to decide where to store your metadata backups. If you only have one iSCSI drive, then use that. From XenCenter, right click on the Storage Repository where you want to store your backups. Choose "Set as default". This will put a black check mark over your SR. If the black check mark is already there, then your SR is already the default.

Click on the host machine in XenCenter, and click the console tab (or ssh into the XenServer host).

Type "xsconsole" into the terminal. Choose "Backup, Restore and Update". Choose "Schedule Virtual Machine Metadata". (enter your root password if it asks). Choose "Daily". Choose "OK"

Now you have scheduled backups every night! If you want to make a backup right now, choose "Backup Virtual Machine Metadata".

In the case of a total failure, you will need to install XenServer, attach your iSCSI, and then do a "restore" from this same menu. After the restore completes all your VM's will showup in XenCenter!

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Yes, as long as you have a current metadata backup. The metadata restore from backup (configured in the xeconsole, the console GUI) is required to attach the storage repository to a new XenServer or XenServer pool.

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  • what is a metadata backup? how do I create a metadata backup? can I do that within xencenter? – 001 Nov 8 '10 at 13:48
  • I think you need to RTFM here, these sound like basic administrative functions. – SpacemanSpiff Dec 26 '10 at 3:37

Yes, you can do that.

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It is important to save all your metadata.

I use crontab on XenServer to backup hypervisors and Pooldata.

All backup data is stored in NFS storage, the independent server.

There are examples of my backups.

Pool data

22 */3 * * * xe pool-dump-database file-name=/var/run/sr-mount/48e3f1ab-e70c-8706-6a14-5a9e7e2cabaf/xen-backup/pool-dump-database-$(date +\%Y-\%m-\%d-\%H:\%M:\%S)


10 3 * * * xe host-backup host=ruth file-name=/var/run/sr-mount/48e3f1ab-e70c-8706-6a14-5a9e7e2cabaf/xen-backup/backup-ruth-$(date +\%Y-\%m-\%d-\%H:\%M:\%S)
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