Re: [Libguestfs] [libguestfs] Options for hotplugging

>(3) The "serial numbers" option > >This was Dan's suggestion. Hotplugged drives are known only by their >serial number. ie. We hotplug them via libvirt using the <serial/> >field, and then they are accessed using /dev/disk/by-id/serial. > >This is tempting, but unfortunately it doesn't quite work in stock >udev, because the actual name used is: > > /dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_SERIAL > >We could add a custom udev rule to get the path we wanted. Presumably you would specify then serial number when adding the drive? I'm not opposed to this, but it's not the simplest.

>(4) The "rewriting device names" option > >Since we already have the infrastructure to rewrite device names, we >could do some complicated and hairy device name rewriting to make >names appear continguous, even though there's an hidden appliance >drive. > >This is my least favourite option, mainly because of the complexity, >and complexity is bound to lead to bugs. I don't think this rewriting is required. Having a hole in the drive letters isn't a big deal. In fact, I suspect it would be simpler in most code to use returned rather than calculated device names. I'd suggest a very simple api: char * guestfs_hotplug_drive(g, path, <opts>) This does the same as add_drive, except that it works after launch and returns the api name of the newly added drive. list_devices will return a list with a hole in it. If it isn't already there, we can add some generic code to methods taking a Device parameter to guard against passing in the root device.