Time Machine 108GB initial backup about 2.5 hours

Question

I had a few issues getting Time Machine to do it's initial backup.
Here are some tips that might help you.
1) In System Preferences, Spotlight, Privacy, add the external drive so it will not be indexed (included in Spotlight searches). I would assume it's okay to remove that setting after the initial backup.
2) Before doing the first Time Machine backup, do a Shut Down... and then press the power button to boot up.
3) During the initial backup. Do not open the Finder. At least, don't open the Finder for the backup drive. When I did that, the drive would start thrashing and the data transfer would slow to a crawl. Not sure what the heck the drive was doing.
4) With a WD My Book Premium 320GB Drive, connected via FireWire, I got about 0.7 - 0.8GB copied per minute. When the backup was running too slow, it was about 30 - 40MB per minute (that would have taken forever.)
Here's the whole story:
I turned Time Machine on in the System Preferences and selected my Western Digital My Book Premium 320GB drive(connected via FireWire 400). I was already doing backups to this drive with ChronoSync, but there was enough room for it to do the backup of my system with room to spare. (I will free up more space by deleting that backup after I'm sure Time Machine is good.) Time Machine started doing it's initial backup and I noticed that it was going very slow... about 25GB after about 3 hours, which is pretty pathetic. I stopped it because the drive was thrashing like crazy and it didn't seem to make sense that it was doing that. It seemed like Spotlight might be trying to simultaneously index the drive, thus slowing things down. I added the drive to the Privacy setting on Spotlight, so it is now excluded. Then, I deleted the Backups.backupdb folder and emptied the Trash. After that, I rebooted. I then started the whole Time Machine initial backup again and it seemed to run much faster, so I let it go for a bit. I had about 25GB copied after about 30 minutes. Much faster. However, I decided to open up Finder and take a look at the Backups.backupdb folder to see what it looked like. After doing that and seeing the *.inprogress file, the drive started thrashing again and the copy slowed down. I stopped it again, deleted the folder again and rebooted. Started Time Machine initial copy again. Very slow this time. So, again, I stopped it, deleted the backup folder and this time, I shut the computer down. I let it sit for 10 seconds or so, then started it back up. Started the Time Machine initial copy again and it was going fast again. I think the shutdown cleared out something. ( a cache maybe?) Anyway, I made sure not to open Finder again during the initial backup and left it running. After about 2 - 2.5 hours, the initial backup of 108GB was complete. I just heard it do it's first hourly backup, which was basically nothing, because I haven't made any changes to anything yet.

Answer 1

Time Machine backups to AirDisks (e.g. USB HDD attached to Extreme) is unsupported, but has been successful by some. As well, once you decide to move any old TM backups (HDD connected directly to the Mac) to an AirDisk, you cannot continue backing up to your previous TM backup. The format it saves to vs. a local HDD is different. The folder structure you see becomes a sparsebundle/disk image via the AirDisk.
If you are interested in proceeding with your plan, check these links out:
http://discussions.apple.com/thread.jspa?messageID=8225748&#8225748
http://discussions.apple.com/thread.jspa?messageID=8650723&#8650723
http://jamesshore.com/Blog/How-to-Accelerate-Time-Machine.html