[libvirt] libvirt-guests - order of stopping/starting guests

Hi all, on a previous thread [1] Eric Blake mentioned: I poked around the code and experimented a little bit and found the following. * When you first create new guest (or start already created guest) it is assigned a sequential ID, name and also UUID. IDs start from 1 and increase as long as libvirtd is running. * When libvirt-guests wants to start/shutdown guests it relies on the file /var/lib/libvirt/libvirt-guests. The format of this file is: URI <list of uuids> libvirt-guests script will start the guests as written in the file. * The libvirt-guests file is initially created from the output of `virsh list' and `virsh dominfo' (to get the UUID). virsh list will list the guests ordered by their ID. * Order of starting/stopping guests is unreliable. The only thing that matters wrt start/shutdown order is the guest ID at the time when the libvirt-guests file is generated. By default the order is the order in which guests were created and it can change if you randomly stop/start guests while libvirtd is running . Names or UUIDs don't play here at all. I'm not exactly sure what IDs are used for but they change every time when a guest is stopped/started manually. Which in turn reflects the order in which libvirt-guests stops/starts all guests. Example: On a freshly installed system I created 5 guests in the following order: a1, b1, a2, c1, a11. Then I left all guests running. Upon stop/start of the libvirt-guests service the guests were stoped/started in the same order. Then I stopped libvirt-guests and libvirtd, renamed a1 to c2 and restarted both services. c2 was first in the list - name doesn't matter. virsh list shows IDs are 1 to 5 (c2 = 1). Then I did: virsh shutdown c2 && virsh start c2. c2 now has id of 6. Doing service libvirt-guests stop/start again now showed me a different order: b1, a2, c1, a11, c2 You see how the order in which guests are started/stopped is unreliable. If I were to stop c1 while all other guests were running and then start it again (e.g. after attaching a new disk image) then it will have the highest ID number and will become last in the list used for stopping/starting guests. I'm not sure if this can easily be fixed or it needs the concept of groups/relations implemented. [1] - https://www.redhat.com/archives/libvir-list/2011-April/msg00789.html Regards, Alexander.