Lets say I would like to make a large volume from external usb drives. I create the lvm volume on drives that have been given certain device names sdf sdg or whatever and at some point they are plugged in differently or in different ports will the volune still be mountable? will I have to change things to mount the volume ? Perhaps it's possible to work around this using UUIDs at the physical volume level? For bonus points is it possible to convert or migrate from device names to uuids ? I'm thinking perhaps through a sequence of pvmoves  
Can lvm2 volumes based on device names like sda, sdb etc be mounted if their names change?
hardware;lvm;storage
Actually I found the answer eventually here: lvm2 FaqThey are identified by uuids always even if you create them using device names and so are resilient if devices are renamed due to renumbering of devices I found that I needed to reboot when I changed drive numbers by changing usb devices to have the new positions used by lvm, running vgscan, lvscan or pvscan didn't update the volumes.FWIW using LVM on multiple USB devices is a bad idea. I was only doing this because I was stuck and had no option.