[Qemu-discuss] Best way to obtain a memory snapshot in QEMU

[Arnab]

Hello,

I am trying to obtain a memory snapshot in QEMU. The steps I follow are 
as follows:-

1. I will run a workload on the Virtual Machine. The VM is running 
Ubuntu 16.04 on a x86_64 machine.

2. After running the workload (a spec2006 workload that runs 32 sec), I 
will immediately pause the VM. This activity is non-deterministic. (I 
will pause the VM as soon as possible).

3. After pausing the VM, I will collect a memory snapshot using the 
below command -

virsh snapshot-create-as --domain generic --name 
generic.snapshot.20170716.img --memspec 
file=/var/lib/libvirt/images/snapshots.16jul/mem.img,snapshot=external 
--atomic

4. After creating the snapshot, I will "un"-pause the VM and carry on 
with my work.

I believe the --memspec command is creating a memory snapshot file.

I wanted to know if this is the right approach to create a memory 
snapshot. I have read about articles stating that we can take memory 
snapshots only if the VM is live and running. Is this correct ? Will 
taking a memory snapshot after pausing the VM give me an accurate 
representation of the VM's memory ?

Thanks and Regards,
Arnab