Memory and snapshot management

[MariusRoma]

Where can I locate in depth information about memory and snapshot management in VMware workstation?

Memory:

• How is memory allocated in the host PC?
  
• If I sart a guest VM with 2 GB RAM using 500 MB RAM on a host PC with 3 GB RAM, how much memory is allocated on the host?
  
• What is expected to happen if I start more guest VM and the sum of memory is more that the available RAM on the host PC?
  

Snapshot:

• How are managed snapshot forom the host PC file system view?
  
• What is the role and contents of the files being created each time I take a snapshot?
  
• What is it expected to happen if I delete a file containing a snapshot (the file, not the snapshot)?
  

Regards

marius

[bhaverkamp]

>

> If I sart a guest VM with 2 GB RAM using 500 MB RAM on a host PC with 3 GB RAM, how much memory is allocated on the host

>

I find this question confusing. What does "VM with 2 GB RAM using 500 MB RAM" mean?

Short answer is that if your guests use more memory than is available to the host things will run very slowly. This behaviour can actually be configured. I would not recommend using more guest memory than is available on the host.

[AWo]

That is an old document explaining how memory virtualization for Workstation works: http://www.vmware.com/files/pdf/VMware_paravirtualization.pdf

However, under "Edit > Preferences > Memory" you can configure how Workstation should behave.You can set how many memory will be reserved to running guests, however, this memory is not reserrved in advance. You can set if larger or only a small amount amount of guest memory can be swapped out to disk or not. While on this tab klick on the help button and you'll find explanations.

AWo

[MariusRoma]

I apologize for rimsposing my question. When I say What does "VM with 2 GB RAM using 500 MB RAM" I mean a VM configured to use 2 GB and currently using only 500 MB.

After creating the VM and starting it I see that 2 additional GB of host RAM look busy, while in the VM only 500 MB RAM look busy: is it correct?

Should I expect to use as much RAM on the host as the sum of the configured memory of all the guest VMs?

My problem, at the moment, is rightsizing a host to host some guest VM.

Regards

marius

[continuum · Accepted solution]

• 1. How is memory allocated in the host PC?
• 2. If I sart a guest VM with 2 GB RAM using 500 MB RAM on a host PC with 3 GB RAM, how much memory is allocated on the host?
• 3. What is expected to happen if I start more guest VM and the sum of memory is more that the available RAM on the host PC?

• 4. How are managed snapshot forom the host PC file system view?
• 5. What is the role and contents of the files being created each time I take a snapshot?
• 6. What is it expected to happen if I delete a file containing a snapshot (the file, not the snapshot)?

1.that depens on the settings in your config.ini
2. the host may use somethiong between 2200 MB and a few MBs - depends on config.ini
3. either the host says "not possible" or the VM will be started - with extreme settings you can allocate 5x the available physical RAM to your VM

4. and 5.

vmsd-file = list of snapshots used by the guest
vmsn-file = settings and config of the guest when the snapshot was created
00000*.vmdk file = this has the actual data of the snapshot

6. cant be predicted: anything may happen: system may be unbootable or healthy - so NEVER do this

> Should I expect to use as much RAM on the host as the sum of the configured memory of all the guest VMs?

again this depends on your config.ini settings - if you tweak config.ini for best performance then the answer is YES

some good stuff to read http://faq.sanbarrow.com/index.php?action=artikel&cat=78&id=76&artlang=en