Citrix Synergy – Day4
Today I attended the session called “Image Management and Replication with Provisioning Services”. Project Merrimack from Citrix supports vDisk versioning while in use by using a new VHD file with the extension of .avhd which holds all of the changes. This supports VHD chains which allow for multiple streams to several revisions of one vDisk. The vDisk lifecycle management consists of maintenance, test, and production; these are the new device types. Lifecycle operations are New, Promote, and Revert & VHD chain operations consist of Merge (2 ways), Delete, and Replication (Import / Export). These can all easily be seen within the NEW vDisk Versioning User Interface. You can have 10 different versions of the same vDisk and in this interface tell it to boot production devices from any of those specific versions. So in the new PS every update and every merge performed creates a new version of the vDisk. You can have Provisioning Server perform an automatic merge after a pre-specified number of versions have occurred. From a performance perspective, the longer the VHD chain becomes the more IOPS and memory it will consume.
So as I got into the lab, I started wondering “What version were we actually doing this on?” As it turned out, this was Provisioning Server version 6.0 that we were doing the lab with as you can tell from the screenshot to the left. The screenshot to the right you can see the new type category which now states ‘Production’. This is called ‘Project Merrimack’ which is in Alpha code currently and there is not a current ETA on this version.
One of the surprises for me was not that we were working with deployment of XenApp through PVS, but we were working with “Project IronCode” which is XenApp version 6.5 which does not use DSC anymore, but it has gone back to a similar interface feel and look as XenApp 5 originally had and it is called Citrix AppCenter. 
It makes me wonder if they did not abandon the XenApp 6 interface because there were so many complaints about it being slow to open and administrate from.
The interface for XenApp 6.5 was extremely quick and responsive and took hardly any time to start up and get going. It appears as if Citrix is going for a singular look and feel across their product line which is a breath of fresh air if you ask me.
The Provisioning Service Console in 6.0 shows the Versions selection now when you right click on a particular vDisk. In this exercise we were requested to make a new maintenance version and make sure that we boot one of the devices in the collection off of the maintenance disk or .avhd file. As you can tell below, the VHD revisioning console shows the Base disk version 0 and the maintenance version which happens to be version 1.
We then placed the specific device into the type called maintenance.
Then we made sure that the boot selection showed the maintenance revision and forced the boot to that version.
At this point you would update the disk by installing applications, security updates, service packs, or whatever you wanted to revise. Then go back to the PVS Server image and right click choosing Versions. Select the maintenance version and then click on Promote setting the version access to Test and clicking OK.
One thing that I really liked about this is that you can select the version and click on properties thereby writing a description of what was done on the disk. This gets away from our best practice of having to keep up with a .txt file with all of the revisions and description of what was done.
Below shows a device in Maintenance mode (Win7.2.avhd) and one in Test mode (Win7.1.avhd). Notice that Test is in Private Image mode and Maintenance is in Standard Image mode.
Below is a glimpse as to what the file structure now looks like.
When you try to promote an image from Test to Production that is in use you will receive an error. You can obviously perform this function after shutting down the VM which is attached to that vDisk version. By right clicking on the vDisk in question and selecting Show Usage you can easily see every VM using any revision of this vDisk.
By right clicking on the vDisk and selecting Replication Status you can quickly tell if replication to/from the other PVS servers is finished or not. As of now in ‘Project Merrimack’ (currently in Alpha code) this feature is not complete, but it will be very cool when this is LIVE and production ready.
By selecting an image and clicking revert you can demote an image from Production to Maintenance or Test.
The final Citrix event of the night was hosted by Train. The concert was excellent and the food was pretty good too.
