Snapshot Files ?

[TonyJK]

When I create a snapshot of a VM, I find that it produces 2 additional files (Please correct me if I am wrong) - One is XXX000001.vmdk and other is XXXsnapshot.vmsn.

I would like to know what is the difference between the original XXX.vmdk file and the XXX000001.vmdk file ? If we would like to backup the snapshot (Like VCB), which VMDK file should be backed up ?

From memory, in ESX 2.5, the snapshot file is called REDO log and later, it is named as Delta file. Does it get a new name for ESX 3.0.2 ?

Your advice is sought.

Tony

[virtualdud3]

My understanding is that the original.vmdk is just that - the .vmdk at the time the snapshot was taken.

The original-000001.vmdk is the REDO log file/diff file. This just keeps track of the ongoing changes between the original.vmdk and the current "state" of the VM. So, if you delete the original-000001.vmdk file, the VM will return to its state at the time the snapshot was taken. This is an important point, as I have encounted many people who incorrectly believe that if they delete the original-000001.vmdk file, the VM will remain unchanged from its "current" state and they will only lose the ability to revert to a snapshot.

I am not sure what you mean by "backup the snapshot". As a general rule, I have found that if you are looking for a long-term backup of a VM at a given state, I would highly recommend making a clone of the VM rather than taking a snapshot. Snapshots are designed to repeatedly revert a VM to a given state, not long-term backup.

I believe the naming conventions for snapshots are unchanged in ESX 3.0.2.

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[TonyJK]

Dear Mick,

Thank you for your advice.

From your reply, my understanding is that the original-000001.vmdk file is the snapshot file and it will grow when changes are made to the VM. When we consolidate snapshot (Like Delete All), the information in that VMDK file will be merged with the orignal.vmdk file.

Do you have any idea of what the original-snapshotxx.vmsn file stores ?

Moreover, for some snapshot, I also find the following type of files, do you have any idea ?

1) Origianl-000001-delta.vmdk

2) Original-flat.vmdk

[Dave_Mishchenko]

Original-flat.vmdk is the file that actually stores your virtual hard drive data. Original.vmdk is a descriptor file which contain the disk geometry for the flat.vmdk file. You can view this with cat or nano.

The vmsn is a snapshot file which stores the running state of the virtual machine when you take a snapshot. It's similar to a vmss suspend file.

The orginal-000001.vmdk is a descriptor file, just like the one for the vmdk/flat-vmdk files. original-000001-delta.vmdk is where the changes are written to.