Failover (im)possibilities of XenDesktop 7.x Part 7 After the XenDesktop 7.13/14 release
- Published: Tuesday, 25 July 2017
In the earlier article series Failover (im)possibilities I wrote about the failover/load balancing possibilities in XenDesktop 7.x, where part 5 was about Desktop 7.12. In this article I will discuss the XenDesktop 7.13 and 7.14 release and will also go into a bit more detail what is expected in future releases (where possible).
The king is dead, long live the king: Citrix Local Host Cache
This was the title of the starting paragraph of the previous part 6 of this article series. In XenDesktop 7.12 Citrix reinvented the Local Host Cache. As described in that part 6 article this is a new build functionality and although it has the same name as the XenApp 6.5 equivalent it is not the same concept and way of working when the SQL database is not available. Citrix is still advising to have a high available SQL (Cluster) infrastructure available. One of the most heard complains when the feature became available in 7.12 was “limited” amount of VDAs supported (5000 VDA maximum). Another much heard comment was about the requirements on the Delivery Controller to host the Local Host Cache functionality.
Logically in 7.13 nothing changed according to the Local Host Cache functionality. In 7.14 Citrix made an improvement on the amount of VDAs support using the Local Host Cache feature. Within 7.14 the amount of VDIs that can be handled by the Local Host Cache feature is increased to 10000 VDAs in a zone. For a single zone infrastructure the maximum is logically 10000 VDAs, when using a multi zone infrastructure 40000 VDAs can be handled, with a maximum of 10000 VDAs in one zone. Some example: 4 zones with 10000 VDAs is possible, 8 zones with 5000 VDA each, 8 zones with one zone with 10000 and the other zones have 2000 VDA each or any other combination as long you will be under 40000 VDAs each and no zone(s) with more than 10000 VDAs.
Looking at StoreFront I don’t think Citrix will add much more functionality for Failover possibilities, which is also logical as I don’t know what should be added on this topic. Would love to see the possibility to configure the feature to host different stores on different IIS websites to also become available in the GUI (for now only in the PowerShell CLI), but it is workable.
Citrix StoreFront 3.9 introduced some nice enhancements (introduced with XenDesktop 7.13), however Citrix StoreFront 3.11 only contains bugfixes and now new functionality. StoreFront 3.11 is delivered with XenDesktop 7.14. Missing StoreFront 3.10? I guess it is just a naming thingy, as we also did not have XenDesktop 7.10, it looks too much the same as StoreFront 3.1 (as XenDesktop 7.10 would look the same as XenDesktop 7.1).
Published App/Desktops & Zones
In the previous part 5 article I described the zones, where I wrote about in part 6 that the situation has not changed and was still lacking the possibility to determine a preferred back-up zone. Also in XenDesktop 7.13 and XenDesktop 7.14 nothing has changed for this part. A missed opportunity for large enterprise organization especially now the Local Host Cache amount of VDAs have been increased when using multiple zones. Hopefully Citrix will work on such a capability.
In XenDesktop 7.12 Tags were introduced. Although the functionality of Tags has not been changed in both XenDesktop 7.13 or 7.14 I think more insights were shown how Tags can be used. Unfortunate it does not help to full-fill my wish list options, however more use cases could be solved. Daniel Feller did a great job on this describing several scenarios using Tags. Some good articles about this topic are How do I define FailOver servers for delivery groups and How do I migrate a XenApp Worker Group structure. Maybe those scenarios can help you in your infrastructure.
Citrix Provisioning Services
The last releases a new version of Citrix Provisioning Services became available a few days to a few weeks after the XenDesktop release with the same version number. On PVS I can be really short for the failover capabilities, nothing has changed. As already said in part six I don’t think Citrix is investing a lot in PVS as my wishes are not high on the priority list. Also there are still rumors about PVS integrating together with MCS and now also with App Layering. So maybe we need to wait for this “product” to get the last wishes into the product.
In this additional seventh article in the series about Citrix XenDesktop Failover (im)possibilities I took a look what XenDesktop 7.13 and 7.14 brought us for failover possibilities. Actually we can be pretty short as only one thing has been changed and that’s the scalability of Local Host Cache that has increased significantly. On the other part nothing has changed, so my wishlist is not changed dramatically.
Currently my wish list holds the following items.
- Application Priority in a two-way method (or moved to Zones functionality
- Additional priority levels in Zone for failover zones
- Different IIS website StoreFront functionality included in the StoreFront console
- Additional priority levels for Load Balancing in Citrix Provisioning Services
The previous wish list item increase the 5000 VDA LHC limit has been fulfilled, with the enhancements in XenDesktop 7.14 (10000 VDA maximum in a single zone, 40000 VDA maximum per side using multiple zones).