kevinhill
Contributor
Contributor

Storage allocation for a VM (suspend/resume)

Hi,

I am planning a VI3 deployment and was trying to fix the amount of storage that should be made available for a VM. I went through the document vi3_san_design_deploy.pdf which mentions the following.

(Size of virtual machine) + (size of suspend/resume space for virtual

machine)) + (size of RAM for virtual machine) + (100MB for log files per

virtual machine) is the minimum space needed for each virtual machine

Can someone explain to me what is the 'suspend/resume' space mentioned here. Should this be allocated for each and every VM ?

regards,

Kevin Hil

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4 Replies
spex
Expert
Expert

If you suspend a vm the active ram content for this vm is written to disk.

That means maximum needed is ram configured for that machine (normaly not 100% active).

There is also the need to reserve the ram an extra time, since a pageingfile is allocated with size of configured ram.

Regards

Spex

kevinhill
Contributor
Contributor

Hi,

Wow, that was a fast reply.

The same document that I had mentioned also mentions the following

NOTE: Size of suspend/resume snapshots of running virtual machines is

equal to the size of the virtual machine

This was what confused me.

So what you are saying is that I need to provision for additional space equal to the RAM and not equal to the size of the VM itself. Is this correct?

regards,

Kevin Hill

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spex
Expert
Expert

Suspending is a different to snapshoting.

Suspending does not remember changed blocks of your virtual machine disks.

Snapshots store chnged blocks of the original. So if you change 100% of your vm's disk you need 100% of this disk.

If you are doing a second snapshot you can even need more than 100%.

But normaly you stay in lower regions.

If you delete snapshots all of the changes within the snapshotfile have to be written to the original disk. So a time consuming step....

Regards

Spex

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kevinhill
Contributor
Contributor

Hi,

thanks spex for your responses.

regards,

Kevin Hill

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