[Wylug-help] Help needed with 'failed' Linux software RAID 10

[Dave Fisher]

Some years ago I made the mistake of putting my main home directory on
a LVM2 over RAID 10.

It's been a pain in the backside from the very start, made worse by my
ignorance of both technologies and by the fact that never worked out a
proper backup strategy ... despite several false starts.

Now I've run into what (at first sight) looks like my second
near-death experience with the RAID array ... and just like last time,
I mistakenly deleted both backups a couple of days ago.

mdadm -A -s tells me that my array cannot be assembled from only one
of the four partitions in the array.

My previous lucky escape leads me to hope that there may be very
little wrong with the 'missing' 3 partitions ... other than some
(possible) problem with their metadata.

There is certainly not the slightest indication of physical damage, or
file system errors,  and the entire array was working cleanly until a
system crash some hours ago.

My guess is that someone who really understands Linux RAID could fix
the thing in minutes.

Unfortunately, if I were to say I understand a tiny bit about Linux
RAID, I'd be exaggerating ... so I desparately need advice on how to
set about diagnosing the problem.

The key thing is that there is a small (but critical) amount of data
on the RAID that I cannot afford to lose through 'diagnosis by
tinkering'.

So, good advice on completely safe diagnostics is desperately needed.

If there is anyone out there who does this stuff professionally, I'd
be happy to pay for genuinely expert help.

Thanks in advance.