snapshots

[gymiv]

What is the purpose of snapshots in vserver? Can they be used as backups? I did a snapshot of a machine and it only took a couple of sec. unless it was doing something in the background. Or are snapshots just config settings that work like  System Restore files in windows.

[psplnalin123]

Snapshot is not a backup if the parent disk delete then you will not recover the data from snapshot.

Snapshot is basically contains disk state + memory state. Suppose you take one snapshot after that you applied the patch but after applying the patch suppose you are getting blue screen while booting or getting frequent blue screen. At that time you could revert to the current snapshot after you will do the revert it will move the initial stage where you have take the snapshot and you will find the patch you was applied it will not be there.

[a_p_]

I absolutely agree with psplnalin123. A snapshot is NOT a backup.

Snapshots are mainly used in backup applications to be able to backup the virtual disk image and to be able to revert to a working state in case an installation does not work as expected. However, it's your responsibility to ensure reverting to an earlier state does not result in issues like e.g. a corrupt AD in case you revert e.g. a DC (which you should never do) or an SQL server.

Snapshots should only exist as long as needed, since they can consume a large amount of disk space and therefore cause issues if diesk space is limited.

André

[gymiv]

Then i am somewhat confused. In the directory for the vm every time i take a snapshot it creates a new file. 30k or something to that affect. How is it storing any data. Also i only see an option to revert to last snapshot. What if you want to revert to a snapshot before that?

[Troy_Clavell]

see also, http://kb.vmware.com/kb/1015180

[gymiv]

yes this is the doc that originally made me start asking questions for instance

A snapshot preserves the state and data of a virtual machine at a specific point in time.

• The state includes the virtual machine’s power state (for example, powered-on, powered-off, suspended).
  
• The data includes all of the files that make up the virtual machine. This includes disks, memory, and other devices, such as virtual network interface cards.
  

I can buy the first one no problem but the second one say the snapshot contains all the data but the snapshot files i am seeing are 20 - 30k. Not ver big definatly not big enough to hold any data. I took a snapshot then added some files to the desktop and reverted back to the previous snapshot. The files were still there. I am not sure how this works or what exactly it is doing.

[psplnalin123]

after revert you need to delete the snapshot. Basically there are 2 options delete and revert if you delete then what ever changes you did that will merge to the parent snapshot. and if you will revert then it will revert to the parent snapshot and changes will not remain there and after revert you need to delete the that snapshot.

[weinstein5]

Snapshot are not copies of the disk but the delta changes that have occured since the snapshot was taken - so if the disk is not changing that much than the sanpshot will not grow quickly - 

[gymiv]

Can you set this up to take snapshots at certain intervals like every day or 3 days? Also can you tell it how many snapshots to keep, and where do you access those settings?

[continuum · Accepted solution]

yes - you can.
VMware has a super dangerous feature named Autoprotect - it is available via GUI on Workstation.
On ESXi the developers were smarter and did not expose this feature via the GUI.

Actually I use to call this feature AutoDestruct  - I guess that will tell you what I think about it

Honestly I would not even tell anyone to even consider using it.