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Nov 21 2008   2:25AM GMT

VMware snapshots, live it, love it, learn it!



Posted by: Raj Perumal
VMWare, Snapshot, ESX, ESXi, snapshots, snapshotting

Hi folks, here’s a standard feature of VMware that a lot of people take for granted that I thought would bear mentioning. Snapshots!

So you have an application or patch you want to install and you don’t know what effect it will have on your server. What do you do? Take a snapshot! With VMware you have the ability to take a snapshot of your OS at that point in time and then make whatever changes you desire. After your changes are made you can check to see if everything is working. If there are issues you can just select the snapshot and revert back to where you were before.

I find it quite surprising how many people actually have VMware and forget to use this feature as if they’ve forgotten it’s even existed! Snapshotting can be your best friend when doing upgrades, don’t forget it!

-RP

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Jul 18 2008   12:45AM GMT

VMWare and Snapshots



Posted by: Raj Perumal
VMWare, Snapshot, redo, VMware performance, ESX

This is one of those things you learn the hard way. The ability to snapshot a VM in VMWare is a great feature, but unfortunately if left unattended could grow to be a bit of an issue. Snapshots are great if you need to make changes and need to quickly undo them.

However once you take a snapshot, VMWare starts creating another file which is essentially a copy of all the changes that are happening since the snapshot. Once you are sure you are done with your work you should remove the snapshot instead of leaving it there. By leaving it there, the other file can grow quite large and affect the performance of your ESX server. Also if you finally do decide to remove the snapshot much later on, then the VMWare server will have to write all those changes back into the virtual machine. The more time that has passed, the more changes that need to be written. This can also slow down a server and I have even seen it crash ESX servers to the point where the virtual machines were still running but the ESX server itself couldn’t be managed at all from Virtual Center.

So the rule of thumb is to take a snapshot before rolling out a patch or update of some sort, do your testing and then remove the snapshot in a quick amount of time so it doesn’t have time to grow out of control.

-RP

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