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Open source backup software lags in the cloud and VM backup

The response of open source backup products to server virtualisation and the cloud is uneven. Zmanda offers full VMware and cloud compatibility, but others have yet to catch up.

Since we last looked at open source backup software in 2009, clear trends have emerged in enterprise IT that have affected backup. In particular, server virtualisation has become ubiquitous in production environments while the cloud has become firmly established on most organisations’  IT radars.

The key enterprise backup players have responded to these developments with support for virtual server backup and the addition of the cloud as a backup target. The response from the open source backup software community and commercial supporters has been relatively uneven, however.

Let’s look at those key open source backup software products in detail.

Amanda embraces VMware backup and cloud

Amanda is the oldest of the open source backup products and is available for clients based on Windows, Solaris, Mac and Linux, as well as VMware. Originally developed by the University of Maryland, it is now maintained and developed by commercial organisation Zmanda.

In June 2009, Zmanda introduced Amanda Cloud Backup 3.0. This version added the ability to use Amazon’s S3 cloud service as a backup target. Version 3.1 -- released in June 2010 -- added backup of VMware servers to the Linux, Windows, Solaris and Mac clients already supported.

Amanda backs up to the target using file compression and packaging formats such as .tar and .zip, which are based on open standards widely used for archiving purposes. So, you are not locked into a vendor’s proprietary format but can access that data using a wide range of freely available software packages, although you do of course also inherit any disadvantages of those tools, such as tar's slow performance when handling large archives.

Amanda is wrapped in a GUI that offers ease of use and functionality such as scheduling, automation and tracking. It allows image-level backups of VMware virtual machines in ESXi or ESX. It uses Microsoft’s Volume Shadow Copy Service, which is Microsoft’s way of snapshotting live data, and stores data in Zip64 format, a 64-bit version of the popular .zip compression format that extends size limits in .zip files to 16 exabytes.

Backup of virtual servers is agentless, only blocks changed since the last backup need be backed up and you can selectively restore specific virtual machines.

Zmanda also sells the Zmanda Backup Appliance, a preconfigured backup server that runs as a virtual appliance under VMware ESXi.

Bacula lags behind

Bacula Enterprise Edition was launched in 2009 by the commercial sponsor of the software, Bacula Systems. It is up to Version 4.0.7, released in summer 2011. It can run in Windows, Mac and various Linux and Unix variants, but not VMware or other virtual servers. It also currently doesn’t offer any specialised support for virtual machine backup, treating VMware files like any other large files.

A VMware plug-in is promised on Bacula Systems’ website, although Bacula's support forums do not show widespread demand for this feature. Some users report having developed scripts for the product that provide the ability to work within VMware ESXi.

The commercially supported product features Windows and Linux bare-metal restore, VSS snapshots, a Network Data Management Protocol (NDMP) plug-in for NAS backup, SQL database recording, reporting of backups and a job scheduler.

Meanwhile, the free, community version has reached Version 5.2.1. Launched in October 2011, it adds LZO compression and backup job verification and includes a tray icon for monitoring purposes.

BackupPC not updated for virtualisation, cloud

The latest version of BackupPC is 3.2.0. It was released in July 2010 and has no virtual server- or cloud-related features.

Popularity contest?

Measuring the popularity of any open source backup product is difficult.

In 2009 we used page rankings as a proxy for popularity, because they describe how popular a Web page is compared with all other Web pages.

In 2011, according to, a Web analytics website,’s page ranking is 94,844th, ranks 141,558th and is 747,042th.

If we look at the rankings of SMB-focussed backup software vendors, the open source products appear to have the upper hand. Here we find, for example, CommVault at 183,238th, Atempo at 1,215,716th and Yosemite ( at 1,505,610th.

It is just about impossible to compare these to the rankings of the mainstream Tier 1 enterprise backup products because only measures the popularity of domains. So, for example, Symantec ranks at 1,533rd, but this includes all visits to that domain, which covers its enterprise and consumer backup and security products.

Of course, none of this is evidence of actual use of these products, but it does give some idea of the number of people who have contemplated their use.

Meanwhile, open source product download counts from 1 January 2010 to 8 November 2011 as reported by SourceForge are: Bacula, 577,072; BackupPC, 105,889; and Amanda, 61,821. That puts Bacula way ahead. It must be pointed out, however, that downloads don’t equal actual deployments and that of the three Amanda is the only one to be truly an enterprise product. Still, if only a small fraction of those that downloaded it actually deployed it in a business setting, the SMB-focussed backup software vendors would be envious of those open source downloads.

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