software raid on removable drives for backups

[Mike Reinehr]

With my _very_ limited knowledge of  RAID this may be a case of "fools rush 
in ...", but  I've been spending time this winter setting up new servers with 
software RAID and what you describe sounds feasible to me. Using mdadm and 
writing a RAID superblock to each drive you should easily be able to manually 
assemble (run) your pre-defined RAID devices. Once assembled, you just would 
mount the assembled RAID device, e.g. /dev/md0 read-only, to access the data. 
When finished, unmount and stop the RAID device and unplug the drives. (I 
have no experience with hotplugging SCSI drives -- caveat emptor.)

I would suggest reading up on mdadm & see what you think. If you already have 
the drives and your sure that they hotplug safely, what have you got to 
loose?

cmr


On Tuesday 01 February 2005 03:30 pm, Jason Joines wrote:
>     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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