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Backing up to a pair of USB harddisks?


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I read the Knowledge Base article "How to backup to hard disks (Mac)" (http://www.retrospect.com/en/support/kb/how-to-backup-to-hard-disks-mac), but its Last Update is August 20, 2012 and it seems woefully out of date (talking about Mac OS Standard disks seems pointless these days, and it mentions a preference "Use USB/Firewire disks as Removable Disks" which does not appear to exist as far as I can see.

 

 

Is it possible to configure a Retrospect media set to span a pair of USB disks?

 

 

I currently operate a rotating set of three backup disks (Retrospect does not make this particular easy with the scheduled backups needing to be changed each time, but mostly it works fine). But I need a bigger disk, so I'm considering buying another set of identical disks to double the space and swapping them in pairs.

 

 

One option might be to use Core Storage to make a pair of disks appear as a single disk to retrospect, and I'll probably investigate this, but if there is a native way in Retrospect, that might be better. I am happy to make sure both disks are present at any given time.

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Although a disk media set can't be configured to span two disk volumes, it can use the second and any subsequent volumes as additional members of the media set. (The only downside is, if you are grooming a multi-disk media set, you can only reuse the free space generated on the last member.) Would this meet your needs?

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Thanks Tim - yes, it is quite possible that would meet my needs.

 

I have settled on taking two 3TB drives and RAID0-ing them to make a 6TB drive to avoid Grooming altogether.

 

There is some concern that this double's the failure rate, but I have three rotating (off-site) backup sets (eg a pair of disks) so that should mitigate the issue.

 

If I had gone the 2-member route, and one of the disks failed, would Retrospect be able to cope with that or would it destroy the entire backup set as well?

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If I had gone the 2-member route, and one of the disks failed, would Retrospect be able to cope with that or would it destroy the entire backup set as well?

Losing a member of any media set only loses the data on that member; the rest of the data is accessible.

 

If a member ever becomes lost or unreadable you should mark it as lost in the Media Sets window. That way, Retrospect will back up the data from that member again (assuming, of course, that the files are still on the source volumes).

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