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View Full Version : newbie questions re: partitions, volumes, rotating backups


ChrisJ
05-30-2006, 07:00 PM
Hi,

I just purchased SuperDuper! after researching and finding good reviews. The simplicity, reliability and versatility seem great. I also just got my first external drive (iomega 160GB Black Series FW-800).

After reading a bunch of the manual, there are a couple things I'm still not quite clear on. I was hoping someone here could help sort them out.

Page 4 suggests doing 'rotated' backups, but the idea isn't really elaborated on. How would this work in practice? Say you want to do Smart Updates daily for the current back-up but also want access to a week-old and a month-old version. This functionality isn't critical, but if easy then sure I'll do it.

Page 16 says, "In general, we strongly recommend that you store a backup on its own volume or partition, on a FireWire or internal drive that supports booting the Macintosh." What I'm not clear on is whether you can boot from a volume of a bootable drive (e.g. using the 'New Image' function of Disk Utility). That way I could store more than one bootable copy on my external drive (e.g. for doing rotations), or else keep data like large movie files backed up separately from the my main backup.

Finally, how are partitions different from volumes, and why can't the SandBox effect be accomplished using volumes? I like the idea of a SandBox, but I'm hesitant to partition my computer's drive. (And the manual for the drive I bought says they don't support multiple partitions.)

Thanks!
Chris

dnanian
05-30-2006, 11:19 PM
Hi, Chris. I didn't elaborate because it's relatively simple to do. First, partition your destination into three (or use three different drives, or two, or whatever) -- one volume for the daily, one for the weekly, and one for the monthly.

Then, set up the three backups using our scheduler. One is daily -- so, all weeks and all days. One weekly -- all weeks, one day. One monthly -- one day, one week.

That's all there really is to it.

You can boot from a volume of a bootable drive. A "normal" drive has one volume (partition). You can create more, of course... and all drives support partitions, it's not a hardware function. I don't know why Iomega says that, frankly.

You can store a Sandbox on your external as well, no problem. Just remember that you have to boot and run from a Sandbox for it to be truly useful.

Hope that helps.

ChrisJ
05-31-2006, 12:24 AM
Thanks, Dave.

First, partition your destination into three (or use three different drives, or two, or whatever) -- one volume for the daily, one for the weekly, and one for the monthly.

Then, set up the three backups using our scheduler. One is daily -- so, all weeks and all days. One weekly -- all weeks, one day. One monthly -- one day, one week.

That's all there really is to it.

Hmm. But doing it this way, it seems you wouldn't have access to a week-old version right after the scheduled weekly backup. Same goes for the monthly. And the week the monthly backup happens, you wouldn't have access to a week-old OR a month-old version. Am I missing something?

You can boot from a volume of a bootable drive. A "normal" drive has one volume (partition). You can create more, of course... and all drives support partitions, it's not a hardware function.


When I said "volume," I meant volume in the sense of creating a new "Disk Image" in Disk Utility, and then clicking that to create a "Volume." That's what my Mac calls it when I click Apple-I for info. I assume this kind of volume is different from a partition? So instead of partitioning the external drive, can I create these kinds of volumes using Disk Utility, use SuperDuper! to create backups in each one, and then boot from those? That was my question.

Okay, thanks for your help,
Chris

dnanian
05-31-2006, 07:50 AM
No, you're absolutely right: there's always a point where you update the backup, but you've had it around for a longer time period, during which you could have recovered. (In other words, if you haven't found anything during that week/month you need, it's unlikely you'll need that particular checkpoint and can move the bar forward.)

A Disk Image is just that -- a disk image. It has a volume in it, of course. But you cannot boot from an image: you can only boot from physical drives stored on supported boot devices. Images, though, can be booted from once restored to a supported boot device.

ChrisJ
05-31-2006, 11:41 AM
Okay, then. I see it now. To create a true weekly rotation, you would want two backups. Every other week you would Smart Update the other (like leapfrog). That way there will never be a limbo period: you will always have access to a backup at least a week old.

Thanks for all the help & clarification!

dnanian
05-31-2006, 11:47 AM
Indeed, additional rotations would provide additional rollback capabilities. Similarly, alternating A/B daily backups would allow two-day retrieval.