Wednesday, January 13, 2010

Agentless backup for Citrix XenServer VM's

By:Rick Rohne
One of the great things about Virtualization is the ability to take quick snapshots of your XENServer VM’s so that you have a restore point to go back to at any time; however, keeping snapshots in your XENServer Storage Repositories is not always the answer to a good solid disaster recovery plan.
Take a look at this product which performs automated online snapshots and archives of your XenServer VM's.

There is always a free way for everything

You can use the XENAPI to perform automated snapshots and even schedule this on a Windows Server, you can even go so far as to archive these images off using SSH etc. But anytime scripting is involved, you have to take into account the changes, additions, and deletions of VM’s in your environment. You can learn more about automating XENServer backups using the XENAPI on the Citrix XENServer Codeshare site

Alike (Agentless Snapshots)

I’ve been using Alike to perform automated snapshots and backups of the VM’s in my lab since it first came out of BETA. Alike is a Citrix Ready product that can perform an agentless snapshot and download of your XenServer VM’s to the servers Disk. This may seem trivial, however, Alike actually performs De-duplication of the snapshots and provides an easy to use interface that allows you to schedule a backup job and perform restores without any downtime.
Take a look at some of the key features of Alike:
  • Data Deduplication - Performs block-level data deduplication across all VMs backed up
  • Friendly UI - This easy-to-use User Interface will get you backing up quickly
  • XenServer Integration - Leverages XenServer snapshots to capture guest VM state. Recomended XenServer 5.5
  • Pool Support - Alike is pool-aware and can back up guests deployed to a XenServer storage pool
  • Quiesce Support - Quiesced snapshots are supported in XenServer 5.5
  • Supported Storage Repositories (SRs) - Alike Supports any SR in XenServer 5.5
  • Point-in-time restore - Versions each snapshot that is backed up
  • Syslog integration - Logging can be sent to a syslog server email/paging notifications
  • Flexible Scheduling - Jobs can be scheduled daily, weekly, or monthly; may be configured for multiple runs per day
How Alike Works
1. The Alike scheduler service launches a Job and connects to the appropriate XenServer host.
2. A snapshot of the Virtual Machine (with or without Quiescence) is created.
3. The snapshot image is exported to the temporary work area in an XVA format.
4. Guest image white space is eliminated, then downloaded and processed (deduplicated, compressed and encrypted).
5. Only delta data is vaulted to the storage repository for permanent storage.
6. The backup is now complete and resides safely on disk.

Now if that’s not enough, here’s an excellent video that pretty much tells you the rest of my story:

Keep in mind, however, that even if you are taking snapshots of your VM’s, it is still a good practice to also perform a nightly agent backup of the data that is within the VM. By using both technologies, you can perform an easy restore of your XenServer VM’s so that all the applications and server settings are restored as well as get all the data since the last daily or hourly backup.

My experiences
1. It's much faster than scripting.
2. Works with Citrix Storagelink technology (Netapp storage).
3. New VM's can be automatically added to the Backups.
4. You can even clean up the old snapshots.
5. It would be nice if it worked with XenServer Tags to automate scheduling.
6. I'm hoping it works with Hyper-V and other Virtualization software soon.

For more information on Alike and to get updated pricing, visit their website at

Read about other products that work with XenServer

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