I built a CentOS 7.6.1810 KVM (libvirtd 4.5.0) system, and I have several VMWare converted guests. The guests are CentOS 7.4, Windows 7 Pro, and Windows Server 2008 or 2012 (I think). I have also built a single (so far) CentOS 7.6.1810 guest "natively" (i.e., not converted from VMWare) under this system.

The only one of which I am able to create a snapshot is the native-built CentOS 7 guest. All the rest give an error for which there's not a lot of information:

Naturally, since I'm writing a post asking for help, when I tried again on the CentOS 7.4 guest which is now running (all the previous attempts were on stopped VMs), it worked. The other difference is that I used a snapshot name 'snapshot1' with only alphanumeric characters, and I used 'xxx' for description (no spaces, no non-a/n characters).

Does anyone know if there are rules I haven't found yet, concerning snapshots on converted guests, and/or running vs. stopped guests?

Thanks - Paul

Quick answer: No, I don’t know, but libvirt should have a log file with more information. If necessary, increase the log level.

EDIT: I should have asked you how you take the snapshot.

The successful one I did in the "Virtual Machine Manager" GUI, View | Snapshots | "+" button, Name=snapshot1, Desc='xxx'

The successful one on my CentOS 7.6 guest was in the cli: sudo virsh snapshot-create-as --domain pactest --name "D20181214-B4-xrdp" --description "C7.6.1810 before adding xrdp"

Paul

I suppose you also used VMM or virsh for the unsuccessful snapshots.

That means you use libvirt. The log file and logging options are probably defined in /etc/libvirt/libvirtd.conf. At least that's the location on RHEL-derived distros and Fedora. Check if there is anything in the log; if not, increase the log level and try again.