For those who don't know (this probably doesn't matter, but...), when KVM brings up a system VM, it creates a 'patchdisk' on primary storage. This patchdisk is used to pass along 1) the authorized_keys file and 2) a 'cmdline' file that describes to the systemvm startup services all of the various properties of the system vm.
Example cmdline file: template=domP type=secstorage host=172.17.10.10 port=8250 name=s-1-VM zone=1 pod=1 guid=s-1-VM resource=com.cloud.storage.resource.NfsSecondaryStorageResource instance=SecStorage sslcopy=true role=templateProcessor mtu=1500 eth2ip=192.168.100.170 eth2mask=255.255.255.0 gateway=192.168.100.1 public.network.device=eth2 eth0ip=169.254.1.46 eth0mask=255.255.0.0 eth1ip=172.17.10.150 eth1mask=255.255.255.0 mgmtcidr=172.17.10.0/24 localgw=172.17.10.1 private.network.device=eth1 eth3ip=172.17.10.192 eth3mask=255.255.255.0 storageip=172.17.10.192 storagenetmask=255.255.255.0 storagegateway=172.17.10.1 internaldns1=8.8.4.4 dns1=8.8.8.8 This patch disk has been bugging me for awhile, as it creates a volume that isn't really tracked anywhere or known about in cloudstack's database. Up until recently these would just litter the KVM primary storages, but there's been some triage done to attempt to clean them up when the system vms go away. It's not perfect. It also can be inefficient for certain primary storage types, for example if you end up creating a bunch of 10MB luns on a SAN for these. So my question goes to those who have been working on the system vm. My first preference (aside from a full system vm redesign, perhaps something that is controlled via an API) would be to copy these up to the system vm via SCP or something. But the cloud services start so early on that this isn't possible. Next would be to inject them into the system vm's root disk before starting the server, but if we're allowing people to make their own system vms, can we count on the partitions being what we expect? Also I don't think this will work for RBD, which qemu directly connects to, with the host OS unaware of any disk. Options?
