Comment 22 for bug 1509717

Sorry, I didn't actually test Focal and Groovy.

Xenial will be supported for about a year, so I think it worth to fix it there as well; however it's relative what worth to fix and what not, as most users probably left Xenial behind already or applied a workaround if they were ever affected by this issue. On the other hand it can be a real pain if you don't know about this and just happen to convert your root LV to raid1 and then your system doesn't boot.

"The supported configuration for raid1 is mdadm after all, not removing mdadm and the meta packages that depend on it and using lvm's raid support."

I don't know where LVM over DM-RAID is defined as the "supported configuration" as opposed to RAID1 over LVM. I always thought about them as equal alternatives for slightly different use cases. My rule of thumb is when you can afford to get identical sized disks and mirror everything, go with LVM over DM-RAID. If you can't guarantee to have identical sized disks and need a more dynamic solution, then RAID1 over LVM (i.e. using LVM's raid1 support) is more suitable. I recommend the former in productive server environments and the latter in smaller SOHO, home servers and personal computers. If one of my disks goes bye-bye, I wouldn't want to reinstall my system or lose my documents, so I have my / and /home LVs in raid1. However I couldn't care less about my Steam library because I can just re-download the games anytime, so I don't have it mirrored, as I'd rather not want it to use twice the precious disk space.