On 3/21/25 18:06, Will Mengarini wrote:
* 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?
That mobo has no M.2 slots. Technically I could get a PCIe M.2 card if
I found an exceptional deal on M.2 drives.
Or are you using SATA?
SATA. Spinning-rust even, but that'll change when 1-2 TB SSDs reach
price parity. Heck, they may already be there now that I know about SMR
vs CMR.
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>.
Thanks. After de-duping and removing some old backups, the array has
some 136 GiB (14%) free, so while the end is in sight it's no longer
threatening ominously.
For dealing with humongous multiline URLs like that, I sometimes find
smush() {
tr -d '[:space:]' <<< "$*";
echo
}
to be helpful.
tinyurl or similar is also good.
