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 ?
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.
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?
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....