I got a Western Digital My Book Live for Christmas and have set it up to take Time Machine backups over my home Wifi network.
Unlike many other posts I've seen, my initial backup took a reasonable amount of time in my opinion. My initial backup was about 400 GB and it did it over night in about 12 hours. I did however plug my Macbook into my router via ethernet in hopes that would be faster (the My Book is also plugged into the same router via ethernet). This was 2-3 weeks ago.
Since then, I have set Time Machine to off as I use my Macbook at work each day and manually tell Time Machine to backup when I'm at home with my computer. I didn't want Time Machine to constantly have errors while looking for my backup disc when I was at work and not at home.
I have been trying to a manual backup all weekend now with no luck. I have approximately 5 GB to backup, and Time Machine is only backing up 50 MB an hour if that. I have even plugged in my computer via ethernet again.
Any ideas on how to speed this up? I've also read a lot about Spotlight indexing slowing TM down, but I don't think Spotlight is indexing right now.
I reset the drive and my computer a couple of times and everything returned to normal. I also disabled the drive's "Eco" sleep function so the drive never sleeps - not sure if this is important or not.
I also received an error message at one point stating that the TM backup image was in use. After some quick Googling, I found out that if you have the drive open in Finder it can cause this problem. I then made sure to eject/disconnect from the drive in Finder before telling TM to backup. Perhaps I still had the drive connected before - but not specifically the TM backup share - and that caused it to slow down.