How long should Time Machine take to back up 200GB?

With 200GB of data, I'm assuming you have a bunch of very large files. Something like multiple 10-20GB video files. If that is true, then the time calculations are not accurate because USB2's throughput is too inconsistent. On paper, USB2 has a burst speed of 480Mbps, but often can't maintain that speed over long periods of time. But Windows and OSX's time calculations assume "average copying" of small files and can't correctly calculate when a large file is copied. They see how many "files per second" are being copied, so when it takes several minutes for just one large file, the OS thinks that the copy is slowing down, when in fact the same bits-per-second is happening.

That said, my experience a while ago when copying a single 25GB file, it took 40min using Firewire400 versus 2.5hrs over USB2 to the same hard drive. (The drive had both Firewire and USB2.) You can see why Firewire is usually recommended for transfering large amounts of data. So to improve, definitely replace the USB drive with a Firewire one. I believe your Mac has a Firewire800 port so a 25GB file would be less than the 40min it took with my Firewire400 drive.

So for 200GB of data, my benchmark infers something around 8 hours over USB2. My experience is that USB2 "chokes" when copying for that long so it may take a little more time than that. I mentioned that USB2 can't maintain it's maximum speed over long periods of time. What that means is that some data packets don't copy over correctly and the USB protcol has the packet sent again, which means it actually sends much more than 200GB, in your case. Therefore 8-10 hours would not be unreasonable IMO.

And realize that the calculations you're seeing are for Time Machine, which also has to index/catalog all those files after it's done copy, which obviously will take additional time. Probably not 14 nor 26 days, but using a USB2 drive for Time Machine, definitely overnight at a minimum.

...Given that iPhoto and iTunes are essentially databases rather than images or music is there a further slowdown for indexing or something of that nature? Or is data just data?

Time Machine has to do it's own indexing, independant of iPhoto & iTunes' indexing. In addition, Time Machine may not be able to correctly backup anything that is in use. For example:

iPhoto '11: Back up your iPhoto library

http://support.apple.com/kb/PH2504

I don't know if this has been fixed yet, but as a matter of habit, I always try to close all my apps as much as possible, just to be safe. "Open files" are a problem with many backup programs, not just Time Machine. For example, the enterprise grade Backup Exec for Windows Servers, the Advanced Open File Option is a $500 add on, if one wanted to ensure backing up files left accidentally open by users on the network.

My point is, as the support article says, occasionally close iPhoto and other apps just to ensure that all your documents are backed up correctly, particularly for this initial backup.

zakthedog wrote:

I have an iMac 24" (mid-2007) running 10.7.2 and I'm trying to use Time Machine to back up about 200GB worth of data to a WD My Book for Mac (USB 2.0).

Once all indexing is completed, that should run at, very roughly, about 40-50 GB/hour, overall (it will be considerably slower at first, faster later on).

However, the structure of Spotlight indexes on Lion are different; Spotlight must create a new index for each drive/partition on your Mac. Until your Mac's internal HD is indexed, everything will be slow, especially Time Machine backups.

Then the first backup will be lengthy, as a new index must be created there, too, and of course the new version of OSX and default Apple Apps must all be backed-up.

If the backup is still very much slower than that, see #D2 in Time Machine - Troubleshooting.

zakthedog wrote:

. . .

I tried everything in D2 and also found that my hard drive was set to sleep every 15 minutes; so I don't think its a stretch to think its loosing connectivity and thus causing excessive back up time.

That shouldn't be a problem, unless the drive is beginning to fail and not "spinning up" quickly enough.

Once the indexing gets caught up (if that's the problem), the TM drive should never go more than a few minutes during a backup without being accessed, so it shouldn't go to sleep.

I have 200Gb and it has been 4 days and it seems that it will take 10 more days.

I am using a normal USB.

Hard drive is a Seagate for Mac.

I understand the average calculation part due to file size and numbe rof files, but still in 4 days only 50Gb.

This doe snot seem normal.

Any clues please let me know.

See #D2 in Time Machine - Troubleshooting.