software raid on removable drives for backups

[Jason Joines]

    I'd like to use sets of big removable drives as backup media.  
Ideally, a 3 disk RAID-5 set would be built and a weekly backup written 
to it.  Then, another 3 disk set would be stuck in .....  Only problem 
is I would need to be able to non-destructively reinsert the first set 
to get data off of it if a restore was needed.  Can software raid do this?

    For the past three years I'd been using an Adaptec 2400A ATA raid 
card to do this.  Actually 2 cards.  One card had four 80 Gb drives in 
RAID 5 and daily backups were written to it.  The other card had six 
sets of four 80 Gb that were swapped in and out for weekly and monthly 
backups.  It was much faster and cheaper than tape.  We recently needed 
to upgrade our capacity so an Adaptec 2810SA card was purchased and the 
same thing attempted with big SATA drives.  After many problems and 
destroyed backups Adaptec just told me the card couldn't be used this 
way and it shouldn't have worked on the 2400A either.

Jason Joines
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