On 3/8/2023 4:08 PM, Chris Adams wrote:
Once upon a time, Bowie Bailey <Bowie_Bailey@xxxxxxx> said:
What is going to happen when I try to mount a drive that the system
thinks is part of an existing array?
I don't _think_ anything special will happen - md RAID doesn't go
actively looking for drives like that AFAIK. And RAID 1 means you
should be able to ignore RAID and just access the contents directly.
However, the contents could still be a problem. If LVM was in use on
it, that will be a problem, because LVM does auto-probe and will react
when it sees the same UUID (IIRC LVM will only block access to the newly
seen drive). I don't think any filesystems care (I know I've mounted
snapshots of ext4 and IIRC xfs on the same system, haven't touched
btrfs).
I'm not using LVM on this drive, so that won't be an issue.
My concern is that since the raid info on the drive will identify itself
as part of the active raid, the system will try to add it to the raid
(probably as a spare) when it comes online. I don't think that would be
destructive, but I would have to figure out how to separate it out if
that happens. I'm hoping that it won't be an issue since there are no
missing drives in the existing raid.
I know I will have to bring the drive online as a broken array, but I've
done that from other systems. The only question there is can I simply
rebuild it with a different name. I assume I can just do "mdadm -A
--run /dev/md0 /dev/sdc1" (possibly with "--force" due to the broken
array) even if sdc1 was originally part of the existing md127 array?
The system in question is in a data center, so I'm trying to get ahead
of any possible problems to avoid having to deal with unexpected issues
while I'm there.
--
Bowie
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