Wolf K wrote:


But RAID cannot restore a compromised computer. It merely stores two (or
more) copies of the compromised system. NB that RAID does have error
correction, so it helps reduce file corruption. But it can't protect
against a compromised system, because that is not necessarily the same
as file corruption.

To restore a system, one either repairs it, or replaces it with an
earlier, non-compromised version. That's why you need a back-up scheme.

Have a good day,


Actually, there is one more failure mechanism.

Someone set up a RAID 1 mirror on a SIL3112.

Then, one day, one of the disks died. On a mirror,
the other disk immediately takes over and the user
can continue to work.

Well, on the SIL3112 in question, when the user
examined the Downloads folder, the latest file
on it was three months old. It turns out, the
driver *stopped mirroring* three months
before the failure! Three months worth of
downloads, saved files, were missing. The
only copy of them being on the dead hard drive.

Both funny and tragic. The notion of a mirror
that does not mirror. Who knew...

And this is yet another reason, why your data
should be backed up on an external drive,
and kept well away from that "quality" RAID
implementation.

We had two RAID arrays at work, wiped out by a
firmware bug on the $500 RAID card. In prime time,
at 2PM in the afternoon in one of the cases. Again,
RAID is sensitive to common-mode failures. The
RAID controller card can ruin the array, as can
the power supply, if the 12V rail shoots up
to 15 volts and burns all the hard drive motors.
When I mentioned the possibility of an ATX supply
overshooting like that, someone posted in later
in the day, to say that exact thing happened to
them (ATX PSU ruins hard drives).

Yes, you still want those backups.

Paul