Citrix announced their release of XenServer 7.3 on Dec. 13th, which we’re happy to say Alike fully supports.

XenServer 7.3 includes a lengthy list of new features and improvements, of course as a backup & DR solution the most interesting feature in XS 7.3 is the native Changed Block Tracking (CBT) API.

Alike has provided CBT for XenServer for over a year now, saving users a tremendous amount of time with their backup and replication jobs.   However, at the time we released our CBT (for both XenServer and Hyper-V), no native platform was available so we had to develop our own unique technology to solve the problem.  Now that XenServer provides their own CBT API however, Alike can take full advantage of the power of the XenServer hypervisor’s ability to detect, and track changed data.

So, as of Alike v4.6.2 (#7124), Alike fully supports the XenServer CBT API.  Support is automatic in Alike, so there is no need to configure anything.  When a CBT enabled job is run, Alike will detect if the XenServer host that the target VM is running on supports the new XS CBT API, and it will utilize it.  If the host does not, then Alike will fallback on our pre-existing approach seamlessly.

Please note, as of the writing of this article, XenServer’s native CBT feature is only available in XenServer Enterprise Edition.  You can review the XenServer feature matrix here.

What does the new XenServer CBT API mean for Alike?

The incredible performance of CBT will be essentially identical with either approach.  The most significant benefit of XenServer providing its own CBT API is that it will drastically reduce, if not eliminate the additional SR storage requirements needed to use CBT.   In order to perform the changed data calculations, it is necessary to retain a snapshot (of each VM being protected with CBT), at all times.  Although this snapshot is ‘rolling’, and changes after each backup, it can require a fair amount of extra storage space in your SR.  Leveraging the new XS 7.3 CBT API, Alike is able to eliminate nearly all of the additional storage requirements for the ‘rolling’ snapshots associated with your CBT backups.  This improvement will make CBT backups accessible to nearly all XenServer 7.3 customers.