VMware : Snapshots - Part I
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Let's talk about VMware snapshots today. Apart from all the features we have discussed so far, this feature is very useful in saving lot of valuable time in terms of recovery of a virtual machine.
It is the running state image of a virtual machine including the file system and memory state.
What happens when you take a snapshot of virtual machine?
When you take a snapshot of virtual machine, it makes a copy of the .vmdk file and its memory, saves them along with the other virtual machine files. You can take more than one snapshot of a virtual machine. But the problem is, each snapshot occupies the same size of .vmdk file in the datastore. So if you take more snapshots, more space will be utilized. But a snapshot is a lifesaver when we apply patches or install updates or make upgrades on the OS in the VM. If anything goes wrong with the VM after doing these tasks, we can immediately revert back to the working state. In this way we can save our time without re-imaging the OS on to VM, or re-creating the entire VM it self. Every time maintaining one or two successful snapshots will be recommended in the aspect of space utilization.
How to take Snapshot of a VM?
There are three ways to take a snapshot. Using the VC or VI, by connecting to the ESX hosts we can initiate the snapshot process by right clicking on the respective virtual machine. And the other way is through command line using vmware-cmd command. But whatever the way it is, when you take a snapshot its better to make the virtual machine powered off, some times it is required that the virtual machine must be in powered on state.
Command to take a snapshot from the command-line as follows
"vmware-cmd createsnapshot "
ex: "vmware-cmd winvm1.vmx createsnapshot snapshot1 'before upgrade' 1 1"
NOTE: This technology can be utilized in vmware workstation and in ESX servers also.