Time Machine Backup extremely slow

I recently experienced a hard drive failure on my iMac, and once I actually figured that out and replaced the drive I was happily back on my way with a complete Time Machine restore.

However, I have noticed my iMac has suffered slow Time Machine backups. Typically it takes over 6 hours to complete a differential backup and thats without hardly any changes.

I have tried wiping the Time Machine drive, but I am starting to worry I will have no choice but to do a clean install which completely defeats the purpose of the restore.

Any have suggestions?
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I have two suggestions:

1. Start "Disk Utility" (resides in /Applications/Utilities/ folder). Then do a scan on your start up drive, "Verify Disk" button
2. Check the permissions via the "Verify Disk Permissions" button in Disk Utility

Typically, when I have a slow Time Machine, #1 is the cause.
Are you using a network Airport disk or a USB / Firewire hard drive?

What method is your backup disk connected to your computer?  What stage is time machine halting / being slow on?  
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do you use itunes, iphoto or entourage? If so these maintain a database and have to be copied again for each differential backup as the whole file changes each time it is updated.
RE: gmbaxter - iphoto and iTunes do have libraries that change when you use them, but they are nothing compared to entourage.
RE: Mac 2010. If the problem is caused by a bad directory structure per comment #1, DiskWarrior does a much better job of finding an solving directory problems. The repair permissions idea is a good one.

The other issue could be size of TM drive. It needs to have tons of extra room, or it will go through a long "maintenance" process, consolidating and deleting old versions of files. This problem combined with a large entourage database can really hammer TM. If you are backing up a 500GB disk, use a 1TB backup drive.
AsiaITAuthor Commented:
Running the Verification checks and let you know if this fixes the issue.

Regarding other comments, Time Machine drive is hooked up to an 1TB portable USB drive. The start-up drive is only 500GB so there is plenty of space on the TM drive.

I use iTunes (who doesn't! if you have a Mac) and iPhoto, (not entourage) but i doubt these databases are causing this issue since this issue only occurred after the restore.
> Running the Verification checks and let you know if this fixes the issue.

Good. Keep in mind this will only give you a report of found issues. You cannot fix these while being booted from the same drive. In case there are issues found (probably directory-related), please report those here and I (or others) can give you instructions on what to do.
P.S. You can fix permissions in Disk Utility while being booted from the affected drive.
AsiaITAuthor Commented:
Verify Disk and Permissions did not find any issues.

Back to square one...

More info on the Time Machine status during backup:-

Scanning items is quick, but seems to take a long long time to Preparing items.
Typically it takes 1 min to prepare 1000 items and there are over 1 million items hence it take hours to complete the preparation then there is doing the actual backup.
There are several possibilities:

1. You have a slow network connection -- I have this problem if I am backing up wirelessly from our second floor bedroom, but not when I am backing up from the basement where the wireless router is connected.

See this Apple KB for other suggestions and explanations.  http://support.apple.com/kb/TS1516

Also, try connecting directly to your router by ethernet and letting a backup run overnight. This might fix the problem.

You could also try using your system prefs to turn off Spotlight indexing of your backup drive.
A question about the back up drive. Is it formatted as HFS+ (Mac file system)? Or is it still "FAT" (factory default)?
Does the drive have a Firewire connection?  Are you connecting through a USB Hub?

If you look in console does it hang on a particular file?  Post console log of when it hangs.
AsiaITAuthor Commented:
External drive is connect direct to Mac via USB. External drive does not have firewire.

External drive is formatted in Mac OS Extended (Journaled) the same as the startup drive.

Does not hang on any particular file, it just prepares them extremely slowly.
strungConnect With a Mentor Commented:
Is the drive enclosure USB or USB2?  USB is incredibly slow. You need USB2. If your drive is USB2, make sure the cable is also USB2.

Another thought. Does your drive have its own power or is it relying on getting power through the USB cable?

Also, did you run Repair Disk on both the external USB drive and your internal hard drive?

Try excluding the external drive from your spotlight search.

Are you running any antivirus software? It might be slowing the backup.

Do you have any VMWare or Parallels virtual disks on your drive? These should be excluded from the TM backup and backed up manually periodically instead because TM cannot back them up incrementally.
AsiaITAuthor Commented:

Something weird happend when i got home this evening.

Mac was kind of in a hanged state, i was able to login and move the mouse pointer around but the clock had stopped from lastnight and all the applications that was opened was not responding.

So i decided to cold reboot, once it cameback up, i kicked off a backup and this time it was able to scan, prepare and backup like normal...however right at the end it go stuck on 'Cleaning up' for hours and hours.

Finally i decided to Verify and Repair Disk on the Time Machine drive even though on the verification there was no issues reported.

Ran another backup and this time it was able to complete the backup in a few minutes.

Issue fixed!
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