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Level 2

171 points

Time machine backups take way too long

Greetings,

Having trouble with Time Machine backups taking way too long. (No, it's not the first backup after some momentous event, as 90% of what I read about slow backups mentions; it's _every_ backup.)

20" iMac purchased Oct 2008. OS 10.6.8. 500 GB internal hard drive. 3 TB external backup drive. Was tested at the local "Genius" Bar, but they found nothing wrong with it. The best they could do is to recommend a restore from Time Machine, and if that didn't work, start clean and reload the OS and then copy my stuff back. I don't think so. I actually did a full Time Machine restore for a different reason, and it didn't help (except that I gained a few GB of disk space!).

My Time Machine backups now take about 39 minutes to complete. I have a 500 GB internal drive and this problem happens regardless of which external drive I use. (I have 3: 2 WD hard drives and one [noisy!] G-drive.) My current backup drive is a 3 TB WD drive with 2 TB of free space.

These are small incremental backups, typically about 35 MB. It doesn't take half an hour to copy 35 MB!

All phases take a long time, but the most irritating one is where TM appears to get stuck for a long time at the beginning and end of the copying phase. For example, at one point it will say something along the lines of Backing Up 7 KB of 34.4 MB. And it'll be like that for minutes on end. Later it will say something like 35 MB of 35 MB and hang there for minutes on end. During these periods the write I/O rate will go up and down, and CPU usage will often be very high (with backupd using 90 - 100%, in addition to highly elevated System CPU usage). In one particular backup the I/O write rate for one part of it looked like a heartbeat on an EKG! I should have taken a screenshot.

At the beginning during the Calculating Changes phase, backupd is using between 90 and 100% CPU.

There is also high CPU usage during the next phase, Preparing. And the number of items being prepared is in the thousands.

It always goes in two rounds because it finds that the root directory (/) has been modified.

I've Googled and searched Mac forums and found nothing useful. I started with a new .plist file and nothing's changed.

Can anyone help? Thanks!

I wrote the above Jun 28. Yeah, finally getting around to posting it. Since then it's gotten worse. I now do a manual backup once a day and it takes almost an hour. I tried re-indexing Spotlight. No good.

Can anyone help? Again, this is not a "first backup." It is _every_ backup.

Thanks!

AEF

20, Mac OS X (10.6.8)

Posted on Jul 18, 2013 6:42 PM

33 replies

betaneptune Author

Level 2

171 points

Dec 11, 2013 5:11 PM in response to Unkle e

1. It shouldn't, but from what I researched on this problem, in some circumstances it does. I think I read about it here: http://pondini.org/OSX/Home.html

2. I don't know. Unless there's some big mismatch of something or other, TM should be doing incremental backups.

Sounds easier to me that you just do a Repair Disk on the internal drive than all that copying and re-partitioning.

Backup apps? I'd think so. If your hard drive died, and you reinstalled the OS from CD/DVD, you'd have to go through all the updates.

I always thought that there should be the following partitions, or directory trees: SYSTEM, APPS, DATA. Somewhere in there you need app configuration data. I'm not sure where that should go. But this way you'd have them completely independent of each other. You could back up your DATA more often than the other two. There might be some interactions bewteen them that would make this sceme unworkable. Just a thought to put out there.

AEF

Unkle e

Level 1

6 points

Dec 13, 2013 1:09 PM in response to betaneptune

Thanks for being a helpful and sympathetic ear. It seems TM is now running OK - at least I'm not noticing it much now. So trashing the old backups and starting again in a larger partition seems to have worked for me.

I realise I made a mistake in one comment. I can choose what I do and don't back up, I just hadn't seen exactly how to do that (I didn't find it intuitive). But I agree about backing up everything, when I think about it more. If it's doing incremental backups, a lot of software won't change, and won't slow up backup.

It wasn't too much trouble to re-format the external HD, and I wanted to change the partitions anyway.

But I do wish TM had the option to do backups less often.

I just did this post to tidy everything up, in case someone else searches for the same topic. Thanks again.

betaneptune Author

Level 2

171 points

Aug 21, 2014 5:55 PM in response to betaneptune

I have some news about this problem -- a new clue, that is.

Some months ago the problem started happening again and the make a new partition and hope it kernel panic's trick didn't work. Later I tried it again and it worked! Now backups are getting longer again, but I noticed a pattern. The first time and this time I had changed backup disks and back. So I think that might have something to do with the problem. Does anyone have any idea why swapping time-machine backup disks would cause this?

Time machine backups take way too long