If you don't care about location-based risks (eg fire), then I don't
see why you would bother removing the drives. Leaving disks in the
machine basically only protects you against 'oops' moments (rm -rf and
such like)., but not much else.

In this instance location based risks (fire, earthquake) are a
concern. My original idea when I started exploring backup ideas was
something I could leave unattended to start when I went to bed and if
for some reason I was forced to evacuate in the wee hours of the
morning all I had to do was yank the drives from the server and leave.

As far as oops moments, only the applications have direct access to
files on disk. All user access to disks is via Samba and I've enabled
the recycle bin vfs module.

The advantage in RAID1 is that it makes a copy constantly, so it takes
no time to create the backup - using other methods (rsync, tape,
rdiff-backup) with a huge amount of data, this time can be
prohibitive.

That was part of why I was looking at RAID for the backup. I've also
had a few suggestions about getting an external eSATA drive and
leaving it plugged in overnight. Just have a cron job do a nightly
rsync or such and *if* I have to evacuate, hopefully rsync will be
complete.

Also, I'd say that plugging/unplugging disks would historically be a
problem, but SATA shouldn't be, IMO. Also, there are solutions
specifically designed for plugging/unplugging - which makes the point
moot - so you might consider one of those.

My SATA controller supports hot plugging so I'm not worried there.


-- 
Drew

"Nothing in life is to be feared. It is only to be understood."
--Marie Curie