Jimmy Wilkinson Knife wrote:


At what age does the data become unreadable if the drive has not been
powered up?

Flash is generally quoted as holding charge on a floating
gate for around 10 years.

That means, if you're using SSDs for archival storage, they
should be plugged in and re-written every five years, at a guess.

For a given design, I don't know how to guess at that value,
and the 10 year number is merely a "starting point, ball park number".

If I had an SSD today, that was as old as the oldest hard drive
in the room, chances are it would throw a CRC error or two, signifying
the error correction couldn't fix the number of errors accumulated
in a sector.

It's a mirrored array, and the drives have different SMART data, even
though they're identical and were installed together, so one should fail
well before the other and prevent a problem.

Well, I don't want to propose something stupid to you,
and cause the mirror to break as a side effect. You have
to be careful that any soft-raid methods don't "track"
what you do to them, and then the next time you boot
into the "working" configuration, the status is
degraded and it costs you another rebuild. If you move
one of those drives somewhere so you can read the SMART,
you might upset the array status.

If you don't have SMART visibility, and you insist
on running a RAID 1 mirror, I would recommend
to you that you mix drives from different manufacturers.
Pair an Intel branded 512GB drive with a Samsung branded
512GB drive. That should de-correlate things enough, that
there won't be any unfortunate accidents. I personally
would not pair two identical Intel drives in a RAID 1
mirror, if you paid me :-) I'm be a "lucky enough guy"
to have Windows Defender and Search Indexer keep writing
to C: just after the first drive fails, until the second
drive fails and I'm toasted. That's what would happen
to me if I tried that.

With mirrored drives *you still need backups*.

If the 5V rail on your PSU overvolts, and burns both
SSDs at the same time, "you got nuttin". We do backups
to protect against lightning and PSU failures and ransomware.
The mirror idea, isn't "the Space Shuttle". It's not sufficient
redundancy for disaster planning. It's *not* a substitute
for backups.

Paul