Time Machine hangs. Cannot manually restore

I'm using Yosemite. After changing to a time capsule for wireless backups, Time Machine hangs at the Preparing Backup stage. When I go to look at the Backups.backupd file I used to have with my old attached hard drive to trash the .inProgress file, I now have instead a sparse bundle folder called bands which contains literally thousands of files called things like 1a50d up to eb48 and also files com.apple.TimeMachine.MachineID.bckup, com.apple.TimeMachine.MachineID.plist, com.apple.TimeMachine.Results.plist, Info.bckup, token, Info.plist.

So I can't even do manual restore anymore.

I have searched the internet but cannot find any mention of this. Any idea what's going on here?

Your throughput is going to be dramatically different backing up over WiFi than it would be with a locally attached disk. Have you just let it sit for a few hours while it's 'Preparing Backup'? That first backup is going to take forever, especially if you have a sizable disk on your Mac(s).

Thanks cwa107. I did the first back up with the TC attached to ethernet. Even then it took 20 hours to back up 1.2 TB. So perhaps that all it is, just very slow to respond.

Anyone any idea about this sparse bundle thing? I always liked the idea I could just go into the backup drive and find files manually, but that's not an option now. Is this a Yosemite thing or a TC thing? What are are all those thousands of little files? And will it still be possible to restore a drive with the backup? I cannot find any documentation about this anywhere.

Captain Slocum said:

Thanks cwa107. I did the first back up with the TC attached to ethernet. Even then it took 20 hours to back up 1.2 TB. So perhaps that all it is, just very slow to respond.

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I might be wrong on this, but I'm pretty sure the TC does traffic prioritization and QoS to prevent extremely bandwidth intensive operations tramping on other network traffic. And if this is true, then backups are probably going to be fairly low priority and this would explain the extremely slow initial backup. Fortunately, subsequent backups will be incremental in nature and should be pretty quick. It's just this first one that will be particularly heinous.

Anyone any idea about this sparse bundle thing? I always liked the idea I could just go into the backup drive and find files manually, but that's not an option now. Is this a Yosemite thing or a TC thing? What are are all those thousands of little files? And will it still be possible to restore a drive with the backup? I cannot find any documentation about this anywhere.

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To tell you the truth, I have never had a need to go manually sifting through TM's backup files. I've always found what I wanted either via the Time Machine GUI or via a full system restore. So, I can't really comment on this piece, other than to say that you should keep in mind that Apple designed this system to be dead-simple to operate. The idea was to keep it as hand's off as possible. So, while old hands like you and I will tend to gravitate toward picking it apart, it's really meant to be a "set it and forget it" type of system.

Thanks cwa107. I'm sure you are right about the prioritisation. Perhaps if I'm more patient, things will settle down. As regards the sparse bundle - I was being too clever right clicking on it and unpacking it. Apparently (so I just read) you double click the sparse bundle file and it opens it up to look like the familiar backup file. The sparse bundle is something that happens with network drives, which I don't normally use, so I had not seen it before. There's a great explanation here: How Time Machine Works its Magic How Network Backups are Stored in Sparse Bundles

Totally agree about the "it just works" philosophy, Macs are for people who want to get stuff done, but backups are so precious I like the idea that I can get at the files through finder. (And truth to tell I hate not knowing how things work!). I'll have to accept that with wireless networked drives "it just works - slowly".

Great article, thank you sir. Also, thanks for the laugh on "it just works - slowly".