Time Capsule: Backing up slowly, but surely

Posted by Pierre Igot in: Macintosh
March 2nd, 2009 • 4:40 pm

Using Apple’s Time Capsule for Time Machine-controlled backups for my wife has been a rather frustrating experience. (I don’t use Time Machine or the Time Capsule for my own backups, because I have long used my own SuperDuper!-based automatic backup scheme. But I do use the Time Capsule as a remote disk for manual backups occasionally.)

I have already mentioned the problem with the bad disk image causing kernel panics. This issue was probably due to a bug in early versions of Apple’s software, which presumably has been squashed.

(Since posting that blog item last year, I have also received private correspondence indicating that it is actually possible to repair a damaged disk image without mounting it—which was systematically causing a kernel panic at the time. In order to repair a disk image without mounting it, you just need to drag it to the sidebar of the Disk Utility window and then repair it from there. You can probably also do it with Terminal.)

Another problem with the Time Capsule is the lack of customizability of Time Machine. There is no option to change the frequency of the backups. Fortunately, there are third-party utilities that let you access hidden options to do so, such as TimeMachineEditor. I have been using this software quite successfully to reduce the frequency of the backups to once a day, which is more than enough for my wife.

But then, recently, the Time Machine/Time Capsule combo on my wife’s laptop started acting up for no apparent reason. My wife’s office is a separate room, but the Time Capsule sits in my office, so I can hear it each time it wakes from sleep for backups (which is another reason why I wanted to reduce the frequency of the backups).

Suddenly, I started noticing that the Time Capsule kept waking up again and again, over long periods of time. I went to check my wife’s Time Machine information, and saw that there had not been a proper backup in more than a week.

I tried to initiate a backup manually (via the Time Machine menu extra), but that failed to work as well. The Time Machine backup process appeared to be permanently stuck at the “Preparing backup” stage. You would expect a process called “preparing” (with the animated candy bar that gives you no indication of anticipated duration) to last only a few moments, but in this case it would go on and on, for half an hour, an hour, etc.

I tried all kinds of things, including power-cycling the Time Capsule and the laptop, repairing the disk image on the Time Capsule with Disk Utility (which took a long time, and ended with a report that no problems were found). Eventually, somehow, without really understanding how, I got things to work properly again, and my wife’s daily backup schedule started working normally again.

Unfortunately, after a few days, we had a recurrence of the same problem. For a technology provided by a company that prides itself on products that “just work,” it certainly was not very impressive. I tried all kinds of troubleshooting steps again, but this time to no avail. No matter how many times I power-cycled everything, the backup would always get apparently stuck at the “Preparing…” stage forever, or eventually fail altogether.

I finally ended up going to the Apple Discussions forums to try and find other users with the same problem. And sure enough, I found them:

Not a pretty picture! Fortunately, while browsing through the forum postings, I found clues about what was actually going on. There were reports that, in some cases, a backup failure could leave the disk image in an unreliable state and that the only way that Time Machine had to restore the reliability of the backup was to go through a very lengthy repair process with exhaustive file comparisons.

The poster’s advice was to just let Time Machine do its “Preparing Backup…” thing, even if it took apparently forever.

Of course, a laptop being a laptop, it is set up to go to sleep after a period of inactivity, even when running on the power adapter and not on battery power. So I suspected that either that or my wife’s habit to close the laptop when not using it (thereby forcing it to go to sleep) was what was preventing the “Preparing Backup…” from ever completing.

I went to the laptop and changed its energy saving settings when using the power adapter to never put the computer itself to sleep, only the screen. And I instructed my wife to just leave the computer open when she was done.

And sure enough, a few hours later, when I checked again, Time Machine had completed its backup. And the next day when it needed to update its backup things went smoothly, with a very short “Preparing” phase and a complete backup process that only took 10 or 15 minutes.

So everything is well again now—or is it really?

The thing is, I still have no idea what caused things to fail in the first place. Of all the things that Apple produces, it seems to me that an automatic backup solution for the rest of us should be the one thing that should never fail without obvious reasons, and that should recover in a smooth, user-friendly fashion.

I am sad to report that this does not appear to be the case at present with Time Machine and Time Capsule. When it works, it works fine, and there are no worries. But when something goes wrong, for whatever reason, the recovery process requires extensive troubleshooting on the part of an experienced troubleshooter. That is simply not right. As my wife and all my Mac-using family members say, “What would we do without you?” While this might sound flattering, it is actually an indictment of all things technological, including Apple’s own products.

I cannot help but feel that part of the underlying problem here is that the Time Capsule system is so slow. The initial backup process takes a very long time. (I tried over Ethernet rather than via the wireless connection. It didn’t improve things in the slightest. I still achieved a throughput of only 1 to 2 megabytes per second.) And the reason that the “Preparing Backup…” process mentioned above takes so long is probably that comparing hundreds of thousands of files over such a slow connection is obviously going to take a very long time too.

The thing is, if Time Capsule is so slow, why isn’t the user interface designed to give the user a better idea of how long the processes are going to be? That’s where Apple’s biggest shortcoming is. In their endless quest to simplify everything, they simply have gone too far in simplifying the user interface for the backup process, by withholding duration information that might not be so important when things are running smoothly, but that becomes essential when things start going wrong.

And, if my experience is any indication, things will go wrong. And Apple, I am sorry, but if the “Preparing Backup” process is, all of a sudden, going to take two hours instead of a few seconds or minutes, then the user interface should say so!

Will our Time Machine/Time Capsule combo continue to work properly again now that things seem to have gone back to normal? Unfortunately, since I don’t know what happened in the first place, I cannot tell. But at least the next time the backup process starts getting stuck at the “Preparing” stage again, I will know—and my wife will know—what to do.

Live and learn, I guess.

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