snowmizer
Enthusiast
Enthusiast

General VMWare View Question

We are starting the process of evaluting VDI solutions. I've read a little bit about VMWare's solution. From what I understand you have to create multiple VMs for (one for each user or a pool of VMs say for a department). When you start looking at 20 GB images for even 100 - 150 users you're talking about taking up a lot of space. Granted I realize that with ThinApp you can reduce the size of that image because you don't have to install the apps on each image. Plus the issue of maintenance on each VM. Then you get into the whole issue of backing up the individual VMs for use in a DR scenario.

What I want is the ability to create one "golden" image that everyone gets and then their desktop gets customized with icons based on a profile. This would allow me to do maintenance on (and backup) one VM. I see that VMWare View Composer has something called "linked clones". Does this satisfy what I'm looking for? I guess I'm not really familiar with what a "linked clone".

Any input is greatly appreciated.

Thanks.

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5 Replies
mittim12
Immortal
Immortal

I think Linked Clones would satisfy your requirements. Linked clones are basically a snapshot of a master image so you would have one "master vm" that holds the OS, maybe some core apps, and settings. The linked clones would be running snapshot of that "master vm" that would be greatly reduced in size. I think that linked clones should definitely be used in conjunction with application virtualization as well as roaming profiles to alleviate some of the storage overheard. Below is a link to a blog Tom did on linked clones. It should help you understand them a bit better.

http://planetvm.net/blog/?p=61

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snowmizer
Enthusiast
Enthusiast

Linked clones sound like a step in the right direction. However, my concern would be that if they truly work like snapshots then the size could grow over time (only if you allow users to update the VM?). When the user logs off at the end of the day does the linked clone get destroyed? Has anyone seen a performance degredation with a linked clone?

Has anyone compared this with Citrix's XenDesktop? My understanding of this is that there is one "golden image" and when a user requests a desktop there isn't a clone created so there's no extra disk space other than the "golden image". I don't know much about either product and want to get all of the facts before we make a decision on how to proceed.

Thanks.

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mittim12
Immortal
Immortal

I have not had an opportunity to test it yet but yes I assume it would grow over time as you update the OS and application patches among other things. There is a power off and delete option after logoff. I'm afraid I can't offer any insight into Citrix's product as I haven't tested it yet.

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lamw
Community Manager
Community Manager

Snowmizer,

We've tested Linked Clones on small scale for a lab environment and it's working pretty well (not using VMware View). We're not even using an enterprise level SANs (high performance/etc), standard HP SAN. Linked Clones in VMware View basically allows you to take a single pristine copy of a Master Virtual Machine and allow you to deploy many Linked Clones copy from this single master. The way it works in VMware View as I understand it is, you bring in a Master VM, install VMware Tools and View Agent and then snapshot the VM in it's offline mode. Then what happens is a "Replica" VM is basically copied which acts like a mini-master and then Linked Clones are snapshotted off of that replica. This allows you to deploy say 10 Linked Clones who's reads will go back ot the mini-master and all writes (deltas) will go back to their respective Linked Clones. In terms of performance, I too can't speak on a large scale, it would depend on the SAN and other environmental variables. There is an option in VMware View for a given pool to allow you to basically wipe the deltas after a user has logged off, this would take care of the issue of snapshot growing too large over time.

I believe it's been mentioned a few times but for Linked Clones to really take off, folder redirection and application virtualization needs to be utilized to really get this concept going. You still have the issue of updating your Master and having to redeploy when you have to run patching on your Virtual Machine which per VMware View they're calling this "recomposing, reblance, etc". I'm still not sure of the technical details, but I assume the Linked Clones have to be redeploy, they will not automatically get updated to the current active Linked Clones since their base image could have changed and any changes written by the delta could expect certain things out of the base OS. Linked Clones is not a new technology, it's been around since the early days of VMware products, but View gives is a new way of deploying and managing Linked Clones in a larger scale.

I can't speak to Xen either, hopefully this answers some of your questions

snowmizer
Enthusiast
Enthusiast

Thanks for the replies. You both provided helpful information. I guess the best way for me to determine what's going to work best in our environment is to try both products and see how they perform.

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