* Eben King <e...@gmx.us> [25-03/21=Fr 15:32 -0400]: > I have a 2x1TB RAID-1 array on one of my computers. It holds > a backup. It's starting to become too small, not because it's > shrinking, but because I'm getting more stuff. So, I need to > do something that ends up with a larger array using 3, maybe 4 > disks. It'd be nice if it supports disks of disparate sizes (and > actually uses the extra space), so I can upgrade by attrition. > > I am by no means an expert at mdadm. Heck, I'm barely competent at > it. So I have no particular attachment to it. My friend uses btrfs > to make a (for me) massive array, some 6-8 disks and probably 40 TiB > of space. But it seems he spends a lot of time on administrivia, > balancing the array and whatnot. Maybe that's because it's so > large? Dunno. I've heard there are other filesystems that do > similar things, but I'm not familiar with them. Any recommendations?
LVM is used for this kind of thing. You can install LVM over RAID (which is better than installing RAID over LVM): https://serverfault.com/questions/217666/what-is-better-lvm-on-raid-or-raid-on-lvm This gives a reasonable procedure to follow: https://tomlankhorst.nl/setup-lvm-raid-array-mdadm-linux However, note that if your filesystems aren't already part of LVM, you'll either need to clobber them (trusting backups for restoration, which is slow as well as scary) or shrink your existing partition(s) and use a new one for LVM, planning to extend that new partition by later adding more drives. Hmm, what consumer-level motherboard supports more than 2 NVMe drives? Or are you using SATA? If you need vastly more information and have many hours available for leisurely reading, you might want to look at <https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/ html/configuring_and_managing_logical_volumes/ configuring-raid-logical-volumes_configuring-and-managing-logical-volumes>. For dealing with humongous multiline URLs like that, I sometimes find smush() { tr -d '[:space:]' <<< "$*"; echo } to be helpful.
