Saturday, 28 May 2011

Xenserver Backup solutions

There are a lot of different backup solutions available to backup your VMs. So I've compiled a comparative list of some of the available solutions, and in my next post I will tell you about the one I chose for my backups.

Generic Backup Solutions:
  • No agent needed, it uses rsync, rsyncd or smb
  • File level deduplication across all backups
  • Incremental and full backup scheduling
  • Easy to setup
  • Web interface
  • Command Line Interface
  • No support for tape drives
  • disk-based data backup and recovery
  • Free and Open Source
  • No downtime
  • Free and Open Source
  • No downtime
  • Support for tape drives and tape libraries
  • Uses agents
  • Web interface
  • wxWidgets interface
  • Command Line Interface
  • can encrypt data in transit
  • supports snapshots via Windows VSS
  • Data backed up by Bacula must be recovered by Bacula
  • user postings online indicate that it can be quite complex to set up
  • Free and Open Source
  • No downtime
  • Free and Open Source
  • can back up Linux, Unix, Mac and Windows clients to tape, disk and storage grids, such as Amazon Simple Storage Service (S3)
  • Write to Multiple Volumes in Parallel
  • Support for tape drives and tape libraries
  • Virtual tapes
  • use of native tools, such as ufsdump, dump and/or GNU tar
  • Ability to read the backup tapes without Amanda
  • Uses agents
  • Commercial version named Zamanda with added features such as:
    • web-based GUI
    • management console
    • one-click restore and reporting application agents (priced additionally) for Microsoft Exchange, SQL Server and SharePoint, and Oracle
    • 24/7 customer support
    • orderly new feature release schedule
  • Commercial Version Pricing (,3):
    • Basic:
      • Server $400
      • Linux, Solaris and Windows Cients $150
      • Windows Clients for desktops and laptops $200
      • Backup to S3 option $250
    • Standard:
      • Server $500
      • Linux, Solaris and Windows Cients $300
      • Windows Clients for desktops and laptops $300
      • Backup to S3 option $500
      • Oracle agent $300
      • Postgres agent $300
      • VMWare vSphere and ESXi client $300
    • Premium:
      • Server $750
      • Linux, Solaris and Windows Cients $450
      • Windows Clients for desktops and laptops $450
      • Backup to S3 option $750
      • Oracle agent $300
      • Postgres agent $450
      • VMWare vSphere and ESXi client $450
Acronis Backup:
  • Uses agents
  • Server runs on Windows
  • Supports Tape drives and tape autoloaders
  • Compress backups to optimize your storage space.
  • Save storage space and time by excluding non-essential files and folders from backups.
  • Store backups into two different locations — backup to a local disk and a copy to a network share.
  • Automatic or manual splitting of backups
  • Bare-metal restore
  • Perform remote restores of your networked machines
  • Restore to dissimilar hardware-optional
  • Convert backup images to virtual machine formats compatible with VMware, Microsoft Hyper-V, Citrix XenServer and Parallels environments.
  • install Agent on unlimited number of virtual machines
  • Automated deletion of outdated backups
  • Backup validation and consolidation by Acronis Storage Node
  • Consolidate incremental and differential backups to save space (Deduplication).
  • Templates for backup rotation schemes
  • Centralized management
  • Reporting and monitoring
  • Command line with scripting support
  • Encrypted network communications
  • Costs 1784€ per license
Xen specific Backup Solutions:
Manual Snapshots:
XenServer supports three types of VM snapshots: regular, quiesced and snapshot with memory. Regular snapshots are crash consistent and can be performed on all VM types. The VM snapshot contains all the storage information and VM configuration, including attached VIFs, allowing them to be exported and restored for backup purposes.

Quiesced snapshots take advantage of the Windows Volume Shadow Copy Service (VSS) to generate application consistent point-in-time snapshots. The VSS framework helps VSS-aware applications like Microsoft Exchange or Microsoft SQL Server to flush data to disk and prepare for the snapshot before it is taken. XenServer supports quiesced snapshots on Windows Server 2003 and Windows Server 2008 for both 32-bit and 64-bit variants. Windows 2000, Windows XP and Windows Vista are not supported.

Snapshot with memory save the VMs state (RAM).This can be useful if you are upgrading or patching software, or want to test a new application, but also want the option to be able to get back to the current, pre-change state (RAM) of the VM. Reverting back to a snapshot with memory, does not require a reboot of the VM.

Backup across multiple external disks:
  • back up to muliple esata hard drive's so if you have a 1.5 tb image and only 2 1tb esata hard drives you can span it between both.
  • This will work with any number of drive’s as long as the total combined disk space is larger then the vm’s you are trying to back up.
  • This also works if you only have one drive
  • The backup will be just a little larger then the used space on the drive, so even if you have a 2tb virtual drive but it is only using 500gb it should fit on a drive with 600gb or more freespace.
  • need to manualy create a list of VMs to backup
Zero-Downtime Limited-Space Backup Script:
  • Currently, Windows servers are not supported, only Linux VMs and the XenServer instance, itself.
  • based on using the python API and command-line LVM snapshots
  • No downtime
  • Free and Open Source
  • Limited space - "Doing built-in snapshots of VM's was not feasible for us. Currently, there is no way to exclude disks in a snapshot (that we have found). A snapshot will take about double the currently used space for a disk on an SR, and this space cannot be reclaimed until the snapshot is deleted and the machine is shutdown to be coalesced. In one of our VMs we have about 8 TB of user drive space, with no extra space on the SRs where the disks are allocated. We don't have enough room, nor do we care about creating a snapshot with the user data since it is already backed up with netbackup. The script allows us to get no-downtime snapshots of the system disks with only requiring a small and temporary amount of extra space on the SRs".
  • The python API is used to gather metadata about the VM, its disks, and its network interfaces. The metadata is written to plain text files. The data from the disks is imaged by doing a dd on the lvm volumes that correspond to the VDIs for the disks.
  • To restore, a new VM is created and given the memory and CPUs settings stored in the metadata. Then the VIF and disks are restored with the stored images being written to the new lvm volumes.
  • The script is still a work in progress
  • Support for Windows will be added
TINABS (This Is Not Another Backup Script):
  • It is based on using the python API and tested under XenServer 5.6 FP1
  • This library allows you to create simple scripts to backup the skeleton of one or more virtual machines.
  • Data disks are not included and they are recreated empty
  • The core of the library is the backup() function which iterates through a list of user supplied virtual machine and:
    • gets a snapshot of the system disk, attach it to a brand new virtual machine created based on the parameters of the current one in the list,
    • recreates any data disks on a shared SR (I preferly use an NFS SR as destination due to the fact thatt “For file-based VHDs, all nodes consume only as much data as has been written, and the leaf node files grow to accommodate data as it is actively written. If a 100GB VDI is allocated for a new VM and an OS is installed, the VDI file will physically be only the size of the OS data that has been written to the disk, plus some minor metadata overhead” as stated in XenServer Administrator's Guide) and attaches them to the backup one,
    • recreates any VIFs of the original virtual machine and attaches them to the backup one,
    • exports the backup virtual machine in .xva format on a local directory,
    • completely deletes the backup virtual machine.
  • The restoring process simply consists in importing the .xva previously created and restoring any data from a backup!
  • Live backup and export of virtual machines.
  • I don't care about creating a snapshot of the entire virtual machine including even any data disks since their data are already backed up with a backup tool.
  • Run from a remote host (even a Windows machine)
  • Provide a simple GUI (WxPython + XRC)
  • By default (if running through the GUI) all pool's virtual machines tagged with the current day of the week (in the format: Mon, Tue, Wed, Thu, Fri, Sat, Sun) are selected for backup.
  • A single virtual machine can be selected as well
NOTE: In some cases useing the following scritps the disk space won't be freed after deleting the snapshots, if that happens follow this instructions: but according to this problem is solved in XenServer 5.6 FP1

XenServer Live Backup Script:

  • runs on windows
  • written in VBScript
  • Requires that XenCenter be installed on Windows machine you run the script from.
  • Beta Stage
Filippo Zanardo's Xenbackup Script:
  • written in Perl
  • skip VMs by adding them to a list
  • Optional use of snapshot: if set to true backup script try to make a snapshot of the vm, else he shutdown the machine, export and power on the machine
  • Mail Notification
  • Optionaly create a subfolder in the store for each backup based on vm name
  • versioning: Set to true to let the script manage to delete the backup older than a certain day or number or hours specified in the $delnumber variable
  • automount: if set to true script try to mount the backupdir specified in mountcommand at start and umount at end, else no action taken and u have to mount dir manually
  • checkspace: if set to true the script check the avaiable space on the backup dir and if less than $spacerequired quit with a message, size is in MB
  • Free and Open Source
  • the author is also working on a web based Xen backup solution (
Andy Burton's VM export script:
  • Backup of the entire machine
  • Fast recovery in case of disaster
  • Free and Open Source
  • No downtime
  • VDI removal – Run in addition to the standard vm-uninstall command to stop snapshotted VMs allocating all your disk space
  • Backup VM selection – Select between all, running, none and specifically set (by VM uuid) virtual machines.
  • Quiesce snapshots – To take advantage of the quiesce snapshot functionality if the VM supports it.
  • There is an improved version on (posted in: this version adds:
    • some cleanup scripts to handle disk remounts, removal of older backup images, and some logic to not back up if the backup drive is not present and mounted
    • A plaintext dump of all the info needed to figure out what used to be connected to what and where it used to live, all the SR, VM, VIF, UUID's etc. are here in a reasonably readable format if needed.
    • A sctipt that unmounts and remounts the backup disk, and then cleans it up so that we only have the last two backups on it. Needs some logic to abort if the drive isn't, or can't be, mounted.
    • A script to back up the metadata of the Xen Pool in a restorable format. Backs up the host machines over to the backup drive as well.
  • Back up all the VM's, Xen hosts, and metadata from a single Xen host, so you only need to set this up on one machine
  • Backup destination can be an NFS share, SMB share, USB disk, flash drive, or anything else you can get mounted up.
Markround Script:
  • Similar to the previous but more complete
  • Backup and retention policy can be configured from XenCenter
  • Ability to use a different SR for the backups
  • Agentless backup for XenServer
  • Comes in 3 versions, free, Standard ($899/XenServer Host) and DR ($1189/XenServer Host)
  • Volume licensing
  • Block-level data deduplication across all VMs backed up
  • Friendly UI
  • Versions each snapshot that is backed up
  • Alike is able to backup any or all of the drives in any VM
  • Jobs can be scheduled daily, weekly, or monthly; may be configured for multiple runs per day
  • Alike can run on 64-bit Windows, can back up any guest OS
  • Backup to Any Common Storage Type
  • Alike can fully automate and schedule Citrix's Coalesce tool, dramatically simplifying the reclaim process.
  • Alike can schedule the export, migration or replication of your VMs, providing simple offsite support.
  • Alike installs nothing on the XenServer host operating system (Dom0), and does not require disk from XenServer Storage Repository (SR).
PHD backup:
  • Block level deduplication
  • No downtime
  • Backups saved as VHD
  • File level recovery Any OS, Any File System
  • Removes the need to deploy and manage a separate physical server, additional software, scripts or agents for backup and recovery of the virtual environment
  • Simple to Deploy & Easy to Use
  • Integrate management for backup and recovery into XenCenter
  • Data is checked both during the backup and restore processes ensuring data integrity. Self-healing is provided by automatically detecting and repairing corrupt data blocks.
  • Multiple Data Streams for Fast Backup and Restore
  • Job Scheduling
  • Supports Tape Backup Solutions
  • Application Consistent Backup using VSS
  • E-mail notification
  • Support for Thin Provisioned Disks
  • Backup Storage Warnings
  • Distributed Virtual Switch Support
  • Supports all Operating Systems supported by XenServer
  • Licence per host
  • we own the licences with an optional annual subscription.
  • 1395$ until the end of the month, regualrly 2000$ per server. with one year suppor included (email and phone suppot, updates and patches)
  • 280$ per host for the annual subscription 11/5 EST working hours
  • Resellers in Portugal
  • 15 day trial

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