software raid on removable drives for backups

[Jason Joines]

Roger Oberholtzer wrote:
> Just curious why the RAID for a backup? Just to be sure it is good (a
> damn good reason). Or is there some other factor?
> 
> On Tue, 2005-02-01 at 22:30, 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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> +????????????????????????????+???????????????????????????????+
> ? Roger Oberholtzer          ?   E-mail: roger at opq.se        ?
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> 


	My boss wanted to be able to retrieve data up to twelve weeks old even 
if one drive of a set died.  We were using RAID 5 with 4 drives.  We had 
several drive failures over the years they were in use but no data loss 
thanks to the RAID.

Jason
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