Re: [libvirt] New QEMU daemon for persistent reservations

On 08/22/2017 06:27 PM, Paolo Bonzini wrote: > Hi all, > Sorry for resurrecting old thread but seems like there was no agreement reached. We don't want to expose any paths because the fact that PR helper is a separate binary that uses a UNIX socket to talk to qemu is a implementation detail of qemu. Other HVs may have it differently. However, we want to be able to turn it on/off or not mention it at all on per-disk basis. So what has been suggested so far is: <disk type='block' device='disk'> <source dev='/dev/sda'> <target dev='sda' bus='scsi'/> <reservations enable='yes'/> </disk> for privileged qemu, then: <disk type='block' device='disk'> <source dev='/dev/sda'> <target dev='sda' bus='scsi'/> <reservations enable='yes'> <source type='unix' path='/path/to/a/socket' mode='server'/> <reservations> </disk> for unprivileged qemu, or: <disk type='block' device='disk'> <source dev='/dev/sda'> <target dev='sda' bus='scsi'/> <reservations enable='no'/> </disk> for PR feature turned off (equivalent to leaving it out completely). Now, my question is, in the first case - how should libvirt chose the path? Should it be different for each disk/domain? How is the daemon started in the first place - should libvirt start it? And when should libvirt kill it?