Time machine backup question

[guitarist]

When I bought and set up my Mac Min a few weeks ago, I transferred a couple of my external HDs to it as well, connected them via USB and FW to my new Mini, instead of my old iMac. One of these external HDs contains my Time Machine backups for my MacBook Pro.

When my MBP tried to backup, naturally, it couldn't find that external HD. Because I had moved. So I just now went into Time Machine preferences in System Preferences, to redirect it, so it can find it on the network. So, that worked okay, got it redirected. Then enabled it to begin using that backup location again.

What it's trying to do now, is start backing up on that drive from scratch. When its previous backup is right there, on the drive.

I stopped it, before it transferred 80 GBs of data, as if its backing up for the first time, while I try to remember what one does in this situation.

How do I tell it to pick up and continue using its already-established backup?

[guitarist]

Update:

I see the issue more clearly.

I moved the backup disk from having been directly connected to the MBP, to being on the network.

In the direct connection method, Time Machine doesn't create a sparsebundle, a unique mountable disc image. It just has a backup folder where the data is stored.

Now that the MBP's being directed to the same drive, but which is now connected on my home network, Time Machine is creating a sparsebundle.

Which means it's not using the same backup data as before, it's starting over, creating a new backup image.

Help!

I don't know how to solve this.

[deckeda]

I only know how to overcome this in the future, which is to manually create a sparsebundle yourself first---those can be used either locally or over a network, so when you switch from one to the other (and let TM know it's location) it just picks up where it left off. A side benefit is that you could then easily make backups of your TM backup, since the Finder or backup utility would simply see a sparsebundle disk image to copy.

I keep meaning to write something up here on how I did it (there's more than one way). And today isn't that day.

But in your situation there would have to be a way to convert what you had over to the sparsebundle. I haven't pursued this and don't know if it's possible.

[guitarist]

deckeda, thanks. I was discouraged to see no comments for a long time, it's a quirky problem that doesn't often come up, so few here might have had to explore this.

Your post reminds me that I had gotten curious about sparesbundles, not long after Time Machine was introduced, and because I had an interest in disk images at that time, I read about this unfamiliar kind, using sources on the web. Next, I learned how to make this kind of disk image manually. If I recall, I think you can do it using Disk Utility.

At that time I wanted to manually make that kind of disk image for no particular reason, except curiosity. I was interested in what benefits it might have, how I could make and use one for my own purposes.

Not long after, I drifted on to other projects, and forgot about it.

Perhaps I'll go into Disk Utility and see if I can make that existing folder into a sparesbundle.

Thanks again, I'll report back if I make any progress.

If not, perhaps I'll call Apple and ask for phone help, since my Mac Mini is new, and I have access to 90 days of support.

[deckeda]

The cynic in me thinks calling Apple on this will be fruitless but you never know, give it a try. Or Google something like, "convert network Time Machine to local" or whatever. I'm supposed to be taking a nap before heading out to a wedding tonight or I'd pursue this a little with you today ... I saw your original post but didn't have enough to go on until your second, by the way.

When making the sparsebundle you have to do it in such a way that the Mac's MAC and UUID are taken into account. There's no opportunity to do that with Disk Utility, which can only create normal, non-TM compatible sparsebundle images.

Basically what happens is, when you point TM to use a certain disk or disk image, it matches up info unique to that Mac (using the MAC and UUID) to know whether or not the backup is new or existing to that Mac. Creating the sparsebundle with the info already wedded to it is the trick that lets TM pick right up where it left of, regardless of HD enclosure, network location and so on.

If I can get to writing it up next week I will. Watch this space. In the meantime if you Google how to make your own network TM sparsebundle you'll find the pieces anyway most likely. Another benefit to making your own is that you can limit their growth so that it doesn't just swamp a HD used for other stuff. Good for those of us that really only need a few versions of recent stuff, not months or years of crap they stopped using long ago.

[guitarist]

"convert network Time Machine to local"

it's the other way around, just to clarify. I'm trying to convert a local time machine to network.

I do think Apple would be obligated to come up with an answer, or have suggestions.

At the moment, I'm considering a different direction. That backup is taking up a lot of space, I have redundant backup anyway, and I'm interested in just freeing up the space (trashing that huge file) and starting over.

Ditto for my iMac's TM backup, stored on an external drive connected via USB to my Airport Extreme Base Station. I want to just delete the massive backup (I have redundant, non-Time Machine backup for the iMac as well) and start fresh.

But that brings up a new problem!

Ever try to delete a sparsebundle image?

No can do! Not on a network drive, anyway. The Finder just hangs.

I'm thinking i may have to temporarily plug that drive directly into a computer, then try to delete it.

I'm curious why it resists being deleted. Protection from accidental deletion? Access over the network doesn't like that command?