On 19/03/2023 18:58, Ram Ramesh wrote:
Hi,
My primary DVR is old and I need to move it to more recent hardware.
I have two md raids (a raid1 and another raid6) called /dev/md0 and
/dev/md1. I plan to have root on the new machine on raid1 and thus I
like to rename my /dev/md0 to /dev/md1 in the old machine before I move
it to the new machine. After that I want to move the disks in the most
recommended way to minimize the chance of loss.
Do you have an mdadm.conf, or do the arrays auto-assemble without one?
Since the data is large and usually contains recordings and videos
that have backup on Hulu/Ultraviolet, I worry less about backup. Still
it will be big task to repopulate all my data from the source and
therefore prefer not to do stupid things and loose the data.
Online search showed me a way to rename using just mdadm.conf and that
did not work at all. In fact it messed up my raid6 that I had a panic
for a short time. Luckily, I got everything back working normally. So, I
am not sure which one of the online instructions to follow to rename my
/dev/md0 to /dev/md1 before the move. So, I thought best to ask here.
Your raid shouldn't be named md0 (md1) at all. By default they now count
down from md127 (I think ...)
If you're going to give it a name, give it a name like "root", or
"data", or "home". But I've found that very tricky post-facto - it's
best done when the array is first created.
Also, once I renamed /dev/md0 to /dev/md1, I want to move all 6 disks
in raid6 to the new machine. What is the correct procedure so that after
the movement, I will be able to reboot both the old machine without
raid6 (ie /dev/md1)and the new machine with the moved disks as /dev/md1?
Ideally, I like to teach my old machine to forget /dev/md1 that I want
to move and not touch the disks. If I do not do that, I am afraid my
reboot (of the old machine) will get stuck at some point trying to look
for the missing disks/md. All online tutorial talks about how to
assemble on new machine. Does not talk about gracefully removing an md
from an old machine. I want to know if there is any trick to this other
than shutting down and pulling all disks and rebooting.
Old host runs debian bullseye (linux 5.19, mdadm v4.1) and new will
run debian testing/bookworm (linux 6.1, mdadm v4.2). Let me know if
you need anymore information.
Old host, new host ...
Sounds to me like the best way to move the raid would simply be to
transfer the disks across. The new system should just recognise the
array. If it doesn't you can just put the disks back in the old system.
What I would NOT do is put the old disks in the new system and then
build it. Make sure the new system is up and running before you move the
disks across. (There have been reports of
installers/updates/stuff-like-that not recognising raids and trashing them.)
Thanks and Regards
Ramesh
https://raid.wiki.kernel.org/index.php/Linux_Raid
Dunno where you looked on-line, but this is the best place. Any
improvements you think of, let me know.
Cheers,
Wol
