Citrix Releases XenDesktop 7.12: LHC, EDT, and More

Last week, Citrix showed that it continues to raise the bar on virtualization with the release of XenDesktop 7.12. While Citrix continues to release new versions faster than most organizations can consume them, the strategy behind the accelerated schedule is sound: quarterly releases that excel with regard to planning, development, testing, and overall execution.

For XenDesktop 7.12, there are numerous new features; however, there are three key items that make this release noteworthy:

  • Local Host Cache
  • HDX Enlightened Data Transport and Framehawk functionality
  • Director enhancements

Local Host Cache

This is by far the most noteworthy item in this release. Up until now, loss of connectivity with the Site database meant that the initial session brokering process would fail. While many organizations implemented high availability of the SQL Server database to address issues associated with a single database server issue, a complete failure of the database or SQL Server functionality prevented users from being able to access their virtualized applications and desktops.

For those Citrix administrators who used previous versions, Local Host Cache was a much-used feature that enabled a subset of the database to be retained on Citrix resource so that users could continue to access the system even if the database were unavailable. It’s back with XenDesktop 7.12!

With the reenablement of this feature, the Site database is no longer a single point of failure. As such, administrators won’t receive calls at 3:00 AM when the SQL Servers are being patched and rebooted as part of regular maintenance. While administrative changes can’t be performed when the Site database is unavailable, LHC represents a step forward for redundancy of XenApp/XenDesktop sites.

HDX Enlightened Data Transport and Framehawk Advancements

In this release, Citrix introduces the Enlightened Data Transport layer, which bases the user session on UDP rather than TCP. To step back, the ICA protocol is composed of virtual channels that traverse the network via TCP. Enlightened Data Transport will instead support the virtual channels on UDP. Of course, UDP by nature does not retransmit data packets that are dropped due to congestion, network failures, and other issues; however, EDT takes the best features of TCP and ports them to UDP, making it the best of both worlds.

Although Citrix lists EDT as a non-production feature for this release, it shows that Citrix is thinking ahead about what is next for the ICA protocol. The concern with using UDP is whether corporate and public networks block UDP extensively, making it impossible for EDT traffic to traverse the network.

EDT requires Citrix Receiver 4.6, the version 7.12 VDA, and is enabled via a Citrix policy. In this release, it is not enabled by default due to its experimental state, but when it is enabled, the policy can be configured to fall back to TCP if UDP functionality is not available. Once administrators start testing this feature in their labs, real-life UDP availability can be confirmed. Unfortunately, if UDP is blocked extensively, EDT would not be a next-generation solution.

Enterprises will also need to consider whether EDT and/or Framehawk represent the best go-forward decision for fragile wireless and cellular connections. Until now, Framehawk had some deficits, including lack of support with NetScaler Gateway High Availability, but that has been addressed with this release.  Framehawk is now a viable option.

Director Enhancements

Although the Director enhancements are a distant third following Local Host Cache and the HDX Enlightened Data Transport, improved Director capabilities translate to better management of the XenApp/XenDesktop environment. Key improvements include more detailed failure descriptions, as well as the ability to create custom reports.

Although the reporting functionality of Director has improved dramatically in recent releases, the ability for administrators to now create custom reports through the interface, rather than writing custom queries, makes administration of the Citrix environment much easier. Custom reporting is only available with Platinum licensing.

Those who were considering whether to use Enterprise with a third-party monitoring solution vs. Platinum with the full Director functionality will need to weigh the cost of each against the business and technical needs of the organization.

Overall, this release is a thumbs up for Citrix. Appending XenDesktop 7.12 with Local Host Cache is a milestone achievement that eliminates single point of failure within the Site. That, combined with new protocol functionality that is poised to improve the user experience and monitoring enhancements, continues to demonstrate that Citrix is aggressively addressing its customers’ needs.

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