PVS or MCS – What to do?

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Earlier this year Daniel Feller wrote a great blog article on how to choose between PVS and MCS. This article can be found here.

With the release of the XenServer Intellicache feature and Provisioning Services 6.0 the question is “Is the decision tree still valid”?

This is what I will try to answer in this article.

Before focusing on the why and how let’s start with looking at the original decision tree.pvs-mcs-tree

Now that we have seen the decision tree it’s interesting reevaluate certain decisions.

One decision is about the expectation of boot or logoff storms. If there are we need Provisioning Services. The reason for this decision is based on IOPS.
Provisioning Services is more IOPS effective then Machine Creation Services. But is this still valid now with the release of a XenServer feature called Intellicache?
Intellicache caches the vDisk on local hypervisor storage (like cheap SSD) and therefore offloads the IOPS issue.

So is this decision stil valid? The answer is yes and no! If you use anything else then XenServer use Provisioning Services. If you use XenServer you can go either way.

Another decision is about the need for dedicated VDI desktops. If the need is there you need Machine Creation Services. The reason for this decision is based on the fact that Provisioning Services falls back to Server Side caching when the cache has to be persistent. This method of caching does have some performance issues.
With the release of Citrix Provisioning Services 6 it is now possible to have a persistent cache on a target device disk.

So is this decision still valid? The answer is NO! I’m not saying don’t use Machine Creation Services but I am saying that you can now safely use Provisioning Services for dedicated desktops.

There is also a decision about the need for the provisioning of physical machines like blade PC’s. As Machine Creation Services does not stream images over the network we don’t have to worry about that!

My conclusion is that the decision model needs some small tweaks and changes after the recent releases to be completely valid again. Why I didn’t provide a new one? I will leave that to Daniel as it still is his work I’m following up on!

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  1. BasBas03-21-2012

    Hi Barry,

    See quote below:

    ‘With the release of Citrix Provisioning Services 6 it is now possible to have a persistent cache on a target device disk’

    Do you mean the new ‘Personal vDisk’ option in PVS 6 and higher?

    Thanks.

    • Barry SchifferBarry Schiffer03-21-2012

      No this is different. Before PVS 6 the option to keep the PVS vCache was only available when the cache was on the PVS server, In PVS 6 this is now also available when target side caching is used.

      PVD is completely different technology. The idea is the same, you save changes made to the image, the big difference is that with PVD the changes are also saved when the master image is updated.

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