Small business backups solutions?
Bill McGonigle
bill at bfccomputing.com
Wed Feb 6 00:07:28 EST 2008
On Feb 5, 2008, at 18:23, Ben Scott wrote:
> I've discovered SMART isn't always that smart. I've had drives
> which were actively returning media errors to the host adapter, and
> were then unable to complete the smartctl tests successfully, still
> report their overall SMART health status as good. I imagine this
> varies with manufacturer/drive/firmware/weather/etc.
>
> Just an FYI. Better to have SMART than not, for sure.
Good point. What I was thinking is, "If SMART is complaining you
know to pull the drive". False positives get very little slack in
backups. But you're right, false negatives can exist.
One nice thing about my setup is that all the blocks on the moved
device are exercised on RAID-1 rebuild. Linux is pretty dumb that
way, which works out nicely. And having two copies offsite helps the
odds, even if one drive is bad, you'll have another from the week (or
whatever) before. You can throw redundancy at that depending on your
tolerance for data loss. I often ask, "if your building has burned
down, can you afford to lose a week's worth of data?". That usually
changes minds about needing up-to-the-minute offsite backups.
In my experience I've had to deal with more bad backup tapes than
backup drives. I've also had tapes that apparently can be read only
on the drive that wrote them. And very few folks write FEC data to
the tapes (PAR can be used, and I do on important optical archives,
but is *so* slow to calculate). Warts all around.
-Bill
-----
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