Citrix Project Excalibur – The Future of XenApp is a Little Bleak

I have been working with the Project Excalibur tech preview for a while now and I have to admit… I am concerned.  For those who aren’t aware Project Exclibur is the attempt by Citrix to combine the XenApp and XenDesktop management into a single interface.  And if that alone wasn’t a big enough change, XenApp as we know it is goners.  Instead EVERYTHING is done with the VDA.  While I have long advocated for the combination of the two management environments I never anticipated it would be so… radical.  If you have been a long time XenApp/MetaFrame/WinFrame admin, be prepared for something quite jarring.  Because XenApp is no more.  No more massive infrastructure on each server.  No more IMA service or local host cache.  No, all you have now is the Delivery Agent (formerly VDA) and Remote Desktop Services.  Important Note – All opinions are based on the current Tech Preview and discussion in the forums!

Leo Singleton did a great blog post on Citrix about the new Delivery Agent and all of the features so I’m not going to rehash that.  And both Leo and Chris Lau have been very responsive to issues and concerns in the new Excalibur Tech Preview forum.  That said, my list of concerns about this release are extremely long and unlikely to all be addressed before launch (presumably around Synergy in May).  Let me spell out my top 5 here though:

1) The DA is now king.  Sounds great, and it’s certainly an easier install.  But by making the change to the DA architecture you have lost the local host cache.  If you have a super-reliable SQL environment for your XenDesktop already like say mirrored clustered servers with a witness server, that might night be such a big deal.  But even if you have that kind of environment it STILL can go down from time to time… like if your DBAs didn’t configure the transaction logs right and filled up your data drive :).  Not that I have EVER seen that happen.  But you know, it might!  So with every version of XenApp back as long as I can remember, you have had a local host caching that would allow you to function even when connectivity to the data store was unavailable.  Sure that can get corrupt sometimes, but odds were if your data store went down you were ok for a while.  Not any longer.  When your Delivery Controllers are unavilable or your farm SQL servers are MIA your entire environment is down.

2) The VDA has, to date, been terribly unreliable for us.  We have spent 6 months in constant conversations with Citrix escalation trying to sort out a host of VDA registration issues that lead to random reboots, bluescreens, and general unavailability.  Now not only do I have to worry about whether 30-50 desktops are unregistered every morning, but my servers as well.  DA stability has been an issue even in the tech preview and we have frequently seen deregistration issues.

3) Did you like the features in XenApp 6.5?  Most of them are gone.  If you use worker groups, application pre-launch, or preferential load balancing for failover then say goodbye to them at least for now.  If you like to organize applications or servers into folders, you can’t anymore.  Citrix and Microsoft seem have drunk from the same cool-aid fountain and decided that Search and filtering is all you need.  There’s a rousing discussion on the forum about that right now :).  For those of us who are more visually organized the lack of a folder structure is difficult to get around.  On the other hand, folders always gave us a ton of grief with delegated admins so I won’t miss that!  If you’ve set up everything you know and love around Worker Groups, the fact that they got pulled is also a real problem.

4) Want to publish an app and a desktop from the same servers?  You can’t.  There has been some comment that this will change but right now a server OS can provide Apps or Desktops but not both.

5) Want to create app silos?  Well that now requires 2 steps in Excalibur.  First you have to create a catalog for your Server OS machines where you can select the specific servers.  Then you create App group where you assign that catalog.  Then you publish apps to that group.  Frankly it’s needlessly complicated!  The problem is, much like the architecture of XenDesktop, Citrix is assuming you are using MCS or PVS in a much greater penetration than most major corporations are.  When you create the catalog if it was all provisioned machines it wouldn’t matter because when you assign the number of desktops to the App group then it will just provision that many desktops.  One catalog can service multiple App silos when provisioned.  When you use 1:1 machines though EVERY silo will need it’s own catalog and own app silo.  That’s just insane!  If we could have 1 master catalog for 1:1 servers and then pick which of those went into the app silo then you could avoid a ton of needless catalogs.

Obviously much of this is subject to change and I hope it gets corrected.  There is however one serious stick Citrix has to make us move to Excalibur (or XenDesktop 6, or whatever they call it!).  And that is the support for Server 2012 and Windows 8.  Right now the ONLY support for Microsoft’s latest and greatest is Excalibur and I don’t think we will see any of the current versions made compatible.  Both OSes have fairly significant architecture changes that would prevent XenApp 6.5 and XenDesktop 5.6 from being compatible.  So even though both XenApp 5, 6, and 6.5 are not EOL until 2015 it seems likely organizations will be forced to adopt at least a small Excalibur environment to support the cutting edgers and developers that always seem to demand the latest.

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