Hi Felix, On Fri, Dec 29, 2023 at 04:46:10PM +0100, Felix Natter wrote: > I have /dev/md0 mounted at /storage which consists of two HDDs. > > Now I would like to add an SSD drive for better performance of > VMs. Usually, before doing this, I make sure that all of my disks are > mounted using UUID and not device names. I do not think this is > the case for the two member HDDs of md0 (cat /proc/mdstat). > Is there an easy way to fix this?
What are you trying to fix? Filesystems have a UUID. MD RAID devices have a UID. And MD RAID member devices also have UUIDs, but they are all different *kinds* of UUID. Only filesystems have a filesystem UUID that you use in /etc/fstab and other places. You mount things by filesystem UUID. You don't mount MD RAID member devices; mdadm assembles them. RAID assembly normally happens automatically by udev finding block devices that have the same array id as the one that mdadm is trying to incrementally assemble, until all their member devices are found. So what is it that you are actually wanting to do? If you just want to mount whatever filesystem is on md0 by *filesystem* UUID, you do that in the normal way as it has nothing to do with MD: you use blkid or tune2fs or whatever to read the fs label and put that in /etc/fstab. > If I need to reinstall, can I keep the two member HDDs with all the > data, i.e. does the Debian12 installer recognize the member HDDs > and will allow me to configure /dev/md0? Yes. When you come to the partitioning and software RAID section of the installer your existing md0 should already be there. But to be absolutely sure you may wish to totally ignore md0 and its member devices during install as all their data and the metadata on their member devices will still be there after install. You should just be able to see the assembled array in /proc/mdstat, and then mount the filesystem from /etc/fstab. Totally ignoring these devices during install avoids you making a mistake where you alter one of them. Thanks, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting
