How can I limit the amount of storage consumed by snapshots

[TheVMinator]

Is there a way to limit the amount of storage space that each virtual machine is allowed to use through snapshots? For example - I create a virtual machine with a 50 GB hard drive, using thin provisioning. Snapshots are taken regularly, until the size of the virtual machine hard drive plus the size of all of its snapshots reaches 100 GB. Suppose 100GB is all the storage I want to allow any one virtual machine to consume on the SAN. Can I create a setting either through VMware or through an open-source management tool, that will kick in at 100GB, and prevent further snapshots from being taken once the 100GB limit is reached? I'm looking for a setting that can be set once and enforced for all VM's in the environment.

Thanks for your input.

[lamw · Accepted solution]

afaik, this not possible. You can set a permission on whether a user has the snapshot capabilities, but you can not set a quota/etc. You can not control the number of snapshots a user can take or how much it can grow by. A single snapshot can grow up to the initial size of the VM.

VMware had an interesting survey around snapshot management awhile ago and some of the questions may hint at future features that may allow some type of control over snapshot growth/etc. We'll have to wait and see, but as it stands today, this is not configurable. You can probably write some scripts to monitor these VMs and after it reaches some threshold, you can alert on it and maybe disable the snapshot feature but that will not stop a give snapshot from growing if there are major delta changes.

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[a_p_]

From what you write, I assume you have a different understanding of snapshots than they are implemented in VMware products.

Take a look at http://kb.vmware.com/kb/1015180 This will explain how snapshots work. You will see that each snapshot will be chained to the base disk and already created snapshots. With snapshots, the hypervisor has to read the data block form different vmdk files, which leads to degration of disk performance with each snapshot you take.

André