Suspend and Resume VM much slower on HYPER-V than vmware

jimbo45 · 12 Sep 2016

Hi there

particularly @Kari - you seem to be the resident expert on HYPER-V !!!!

I have two reasonably identical VM's (Linux CENTOS 7 basically runnng SAMBA, PLEX media server, logitech media server and sharing some files).

The shared files are on 2 logical RAID 0 arrays -- Hardware RAID controller used ( actual hardware 2 X 4 TB and 2 X 3 TB 7200 rpm HDD's) connect as RAW HDD's so the native XFS Linux file system is used on the VM's -- no problem there with that BTW.

Running Windows 2010 PRO x-64GB version build 1607 with vmware - suspend VM -- takes about 4 secs. With HYPER-V suspend takes sometimes over a minute.

Both VM's have the OS itself on an SSD and they aren't running concurrently - to get HYPER-V you need to disable vmware and vice versa.

At suspend time the servers don't have any clients accessing them - i.e there's no remote TV's watching streamed video from PLEX.

Any ideas !!! -- can't understand why the suspend and resume function takes so long on HYPER-V -- it's a very useful facility BTW.

Cheers
jimbo

Kari · 12 Sep 2016

First, there are two ways to suspend a Hyper-V vm, Save (#1 in screenshot below) and Pause (#2):

Suspend and Resume VM much slower on HYPER-V than vmware-image.png

Both can also be found in Action menu. Using PowerShell, the cmdlets are Save-VM "vm_name" (to resume Start-VM "vm_name") to save vm, and Suspend-VM "vm_name" (to resume Resume-VM "vm_name") to pause vm.

Difference between these two methods is that whereas Pause only releases all host processor resources still reserving RAM allocated to it, Save releases all host resources, including RAM. Pausing and resuming a vm is instant and the recommended way to suspend if your host has enough RAM to manage without part allocated to vm.

You could say that relation of these two suspend options is as relation of Sleep (Pause) and Hibernate (Save) on a physical machine.

Saving a vm really takes some time. This, the time needed of course depends on how much is going on, how many and how resource hungry processes are running on vm. Testing it just now on three virtual machines with different programs up and running I got Save times from 12 - 15 seconds (resume 5 to 10 seconds, no programs running) up to 25 - 30 seconds (resume 20 - 25 seconds, Windows Update installing updates, a document open in Word, a presentation in PowerShell, video playing in Kodi and so on). These times on low end i5 / 12 GB / 7200 spinner laptop host.

Not knowing Plex I can only guess that it might be at least a partial reason for your slow suspend. Why VMware does this faster, I have not a faintest clue. Sorry.

Tip

Did you know that you can shut down / restart the host letting virtual machines to be up and running? I have selected Save the virtual machine state as Automatic Stop Action for all my virtual machines:

When I shut down the host, all my virtual machines running at that moment will be automatically saved. After restart they are not automatically resumed because I have selected Automatically start if it was running when the service stopped option in Automatic Start Options:

If I want a specific vm be run every time I sign in to Windows on host I would select Always start this vm automatically.

Kari