I received an e-mail this morning from Seth, who was having difficulty getting his initial Time Machine backup completed. Seth graciously agreed to having his question posted here in another edition of Aaron Answers. Below is his question and after the break is my response.
I really appreciate your blog, and wonder if you'd be willing to answer a Time Machine question i've run into. My old backup HD failed, so I bought a new 2T Iomega eGo desktop HD. Partitioned it into 3 partitions, including a 1.1T partition for my time machine backup. All seems to be working fine, except that the backup is too slow to get done unless I leave the computer running for 3-4 days, which I can't do as it's a laptop and I use it all the time. After the first night (8 hours of so) it had only done 20 Gb (out of my 400 Gb). After the second night, it did about 120 Gb. i don't know if I just need to find a 4-day window when I can leave my laptop backing up or if something is wrong with the software. I'm using the new USB2 cord, and it works nice and fast for manually backing up video files etc to other partitions in the drive. The drive seems to work quite fast. If you're able to offer any advice, that would be greatly appreciated!
Time Machine's first backup is a hog
The first time TM backs up your computer it runs slow on average. The slowness isn't because of drive speeds from what I can tell, but rather the amount of data you are backing up. My laptop has about 140 GB of data stored on it. The first time I backed it up it definitely took over night if not quite a bit through the next day. So your 400 GB drive and 3-4 days isn't an estimate that seems too far off the mark. In general (from my experience) once TM gets past the first backup additional backups are incremental and run much, much faster. TM is then only backing up what has changed.
Drive speed and/or connection cables could be an issue
It's possible your connection to your external hard drive isn't as fast as it could be. I'd test it. Use regular USB2 and copy a large (5GB+ if you can) file to the drive. Use a timer or stopwatch and record how long it takes. Next, run the test again with a second USB2 cord (to rule out issues with the first). Finally, if your hard drive supports firewire (IEEE 1394) you should absolutely use it. Especially if it's firewire 800. You may already know this, but there's firewire 400 and 800, and 800 is about the fastest thing on the consumer market right now until USB3 is more prevalent. I do off-site backup with Carbon Copy Cloner to a 250GB external drive via firewire. The first time I did a backup it took one to two hours. That's fast.
You need to get through a full backup. That's the only way to see if you are having longer-term issues with TM or if it's just a matter of the first backup being so burdensome. Second, use the fastest connection your external drive supports. Firewire 800 if possible.
Thank you so much for your detailed response. I left for the morning, leaving my computer to keep chugging away, and was astonished when I returned that it had completed a backup. I was expecting it to run until late tonight, at the very least. I think that both of your issues you raised were going on, especially the first one (as the USB2 cable I'm using transferred quite quickly with drag-and-drop). I think the backup ended up taking about 11 hours. One the first attempt, though, it ran for about 8 hours and only backed up 20 Gb of data before I cancelled it.