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I am using VMWare Workstation 7.x. I have a few Windows Server 2003 images which I use regularly. They all started with the same image and were created by cloning. There is some difference on the software installed after cloning on the different images but it's not a very huge difference - one or two products installed.

After I suspend the images, some resume very quickly - in a second or two. Some take a minute or more to resume.

What could be the reason for the difference - is there a way to optimize a slow resuming image or is there a chance something is corrupted in one of the images.

My host machine is also windows.

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migrated from serverfault.com Jan 29 '13 at 13:32

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Does one of your machines have aktive snapshots by now? –  derty Jan 29 '13 at 8:52
    
Can you specify how you suspend the machines ? Do you hibernate them from within the OS or do you use VMWare's suspend feature ? Are all these VMs allocated the same amount of RAM ? –  Stephane Jan 29 '13 at 9:16
    
@derty - how do I find this out? –  user93353 Jan 29 '13 at 9:38
    
@Stephane - I use VMWare's Suspend Feature. All these have the same amount of RAM. –  user93353 Jan 29 '13 at 9:38
    
in the list view of your machines, right klick on it and look for snapshots -> snapshot manager. You should only be able to see something like "you're here" and nothing else. And the other point is if you have like 4 gig ram und 2 machines running, the second of course will take longer to work because your host-machine has to run the other one who already runs runns too. So the second machine will take loger because it can not claim as much resources as the first one. there are so much caching layers that effect the speed and the complexity of the virtual machine may effect itself too. –  derty Jan 29 '13 at 10:20

1 Answer 1

up vote 2 down vote accepted

As you described, you have some active snapshots on the maschines. This will be the biggest cause of slowness seen from this point of knowlage i have from your description.

Let me explain a bit why and how snapshots work.

Lets assume you create a new machine and install an operating system you wish.  
After this installation one might think it is smart to make a snapshot.  
Actually a very logical thought!  
You could have the possibility to set your system back to its start point.  
Or by making regulary snapshots you would have a very good backup system.  

BUT here is the problem with the snapshots.

A snapshot means that in the moment you create it, your "harddrive" will freeze and a new  file will be created where everything you do that would effect the "harddrive" will be stored.    
The "harddrive" will never ever be changed from that moment since the snapshot.   
Now lets assume you work for hours and hours and everything you change, even changes of the change you made will be saved in this file.

An example, you save the amount of candys you have in the candy.txt.

  • Lets say you save 5 candys.
  • Then you make a snapshot.
  • I eat one of your candys and you change the amount in your file from 5 to 4. (Normally you would save this information directly in the candys.txt. But because of the snapshot this will not happen. What happens is that VMWare create a file (lets call it SERVER.changes) where it saves the change "chronically".
  • You eat one of you candys and again you change the amount in your file from 4 to 3. Since time passes you will now save a change of the change you made before.

So if you want to start your computer from suspend or normal boot or access candy.txt, following happens.

  1. the system will boot from the "harddrive"/open the file changes.txt
  2. then every change will be loaded from the SERVER.changes
  3. changes of changes will be loaded
  4. and so on
  5. now you finally can work on your system/file

So what can you do to have a backup and when would one use snapshots?

  • Backup. I don't know the workstation-version but i guess you can freeze your machine and export/duplicate/clone your machine. This will take a lot of storage, and a lot of the storage will be used for saving data you already saved. So you should back up your data in an other, more efficient way. For the use of backing up your System it is one of the simplest!
  • Snapshot. Well use snapshots when you have to do something you're not 100% secure with. If you have doubt about changing something, or installing some updates and you're not sure if your system will work well afterwards, DO snapshots. You can make a lot of snapshots for every step if you like. It will get slower with the time. But that's ok, since you only want to "try" things and if they work you can delete the snapshot.

Deleting a snapshot means that VMWare will put all the differences recorded into the "harddrive" so when you access your data you'll be working directly at the "harddrive".

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I did not make the snapshots of the slow booting VMs. May be it was already there when I copied it from a different VM. Can I delete all the snapshots? Also the other VMs which are cloned from the slow booting one don't have the snapshot - does cloning remove snapshots? –  user93353 Jan 30 '13 at 9:32
    
Asi i said, not removing the snapshot will cause increasing slowness over time. Removing the snapshot will remove the possibility to set your machine back. I reccomend cloing the machine and then remove every existing snapshot. Cloning will remove the snapshots TO the new machine. The original machine will still have it's snapshots. –  derty Jan 30 '13 at 10:18

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