vmeme file for backing up?

[Shamaya]

Hi,

In a menual doc, I found that the vmem file serves as the virtual machine’s paging file, which backs up the

guest main memory on the host file system. while paging file is easy to understand, What means by backing up the guest's memory？

Is that mean vmware save the whole memory of a VM into the vmem file during the VM is running?

Regards!

Shamaya

[continuum]

if a VM has assigned 2 Gb of virtual RAM this 2Gb have to be stored somewhere.

So VMware stores this as a file named *.vmem

The actual memory of the guest then can move between real RAM and this vmem file.

This behaviour can be configured - see my notes

http://faq.sanbarrow.com/index.php?solution_id=1075




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VMX-parameters- WS FAQ -[ MOAcd|http://sanbarrow.com/moa241.html] - VMDK-Handbook

[Shamaya]

Thank you Ulli Hankeln. You helped me a lot! I found much helpful info in your website. ()

I have another question at this point. does VMware store the entire RAM contents of a VM into the vmem file during it is running or it just swap part of the RAM of the VM out into vmem file? What about when prefvmx.minVmMemPct = "0"?

In your site I learn that When suspending a VM, VMware renames the vmem file and remains it in hard disk. Then before the renaming process, does VMware need to save RAM's current state into the vmem file first?

Regards.

[continuum]

As far as I know the virtualRAM moves between real RAM and vmem-file as required.

if teh VM is idle most goes into the vmem-file - if it is busy it moves partially back to RAM.

prefvmx.minVmMemPct = "0" ...

right now I run a test with prefvmx.minVmMemPct = "1" - it allows heavy overcommitting of RAM but you have to pay that with performance.

I found that 0 makes the host unstable - but that is probably always the case if you use lower settings then available via GUI.

Since 4 days I now run 30 VMs at the same time - each with 512 MB RAM = 15Gb of virtual RAM on a host with 8Gb RAM.

performance is lousy ... but it works




_________________________

VMX-parameters- WS FAQ -[ MOAcd|http://sanbarrow.com/moa241.html] - VMDK-Handbook

[Shamaya]

I found, in Windows XP, When doing suspend operation, C:\WINDOWS\system32\cisvc.exe is used to write page data into vmem file.

But the path name is very strange. my expected path is D:\My Documents\My Virtual Machines\CentOS5_vmware7\564d436d-5b7d-5226-1735-134de6aae3cb.vmem, but here is D:\My Documents\My Virtual Machines\CentOS5_vmware7\CentOS.vmem7d-5226-1735-134de6aae3cb.vmem.

any advice?

[continuum · Accepted solution]

no need to be puzzled

if you check the vmware.log you will see how this will be renamed later

_________________________

VMX-parameters- WS FAQ -[ MOAcd|http://sanbarrow.com/moa241.html] - VMDK-Handbook