Re: How to salvage a degraded mdadm RAID1 with as little data loss as possible?

Am 21.06.26 um 16:12 schrieb Michel Verdier:
> On 2026-06-21, Paul Leiber wrote:
>
>> I just noticed that I didn't manage to make clear that (1) I don't think that
>> there is one specific failed partition, but that both partitions containing
>> databases seem to work, but not at the same time, and that (2) I want to keep
>> the data on the seemingly failed device.
> [...]
>
> I used raid for tens of years and never had the problem you described. So
> I believe it should come from something else than raid failure. raid
> duplicates data on both partitions. If you don't have a failed partition
> the duplication is done transparently and quickly (<second). When a
> partition fails you can add a new and clean partition and the original
> one, the partition still in raid, is synchronized into it. As others told
> you you should use smartd to monitor your disks.
>

My knowledge in IT is limited. I just can describe what I can observe and make guesses. (The md RAID is part of a setup I do for fun at home.) I know that it sounds strange, but my best guess is that there are two differing databases stored on my hard drives. How else can the repeated switch between different data sets be explained?

To comment on your suggestion to monitor hardware status of the disks: Both disks are monitored using smartd (short and long tests being conducted on a regular basis), smartctl doesn't indicate any issue with the drives.