BackBlaze, MDS Worker, and Spotlight

I recently began experiencing my system fans kicking in and running all the time. The fans began running so much that I almost didn’t notice them any more. When I pulled the Activity Monitor up, the md worker was using over 100% of my system resources consistently.

After looking up what md worker does, it appears to be a process spun off by spotlight to index your drive for quick searching. Even after a reboot, the fans would kick back in after a short idle time of maybe a minute. This process was seriously heating up the mac.

After doing some more research, I found this excellent question and answer from the SuperUser site. I ran the following command in the terminal to log what Spotlight was trying on index at the time.

sudo fs_usage -w -f filesys mdworker

The terminal showed the last file to be indexed was in the /Library/BackBlaze/bzdata folder. This was not Library in ~/Users, but the one at the base of the volume. It was indexing this file over and over. My initial thought was that the system was hung on the file. A google search turned up this result on the BackBlaze support page. BackBlaze frequently writes log data to a file. All files in the BackBlaze folder should be added to the Privacy exclusions so that Spotlight will not attempt to index them. According to the support article, this exclusion should be added when BackBlaze is installed. Since the Lion version for BackBlaze was very recently released, this may be a bug in the BackBlaze installer.

In my case, the folder had not been added.

After adding the BackBlaze folder to the Spotlight Privacy exclusions, the problem disappeared at once. Good job on BackBlaze for having an excellent support document.

UPDATE: I recently had to replace my hard drive and decided to do a fresh install rather than pulling over my Carbon Copy Cloner backup. I experienced the exact same problem, and had to follow the process outlined above to fix it. This issue hasn't been resolved in the BackBlaze installer as of yet.

Comments

[Rasmus]

Came to the same conclusion after tracing file accesses by mds using fs_usage, and stumbled on this page when Googling to see if I was alone in my findings. So I just wanted to confirm that more people have the same problem - I had it on both my Macs.

[Matt Henderson]

Hi Mark,

Thanks so much for taking the time to post this. I was experiencing the same, and adding the Backblaze folder to Spotlight Privacy list solved it. (Note that I'm running Backblaze 2.0 on 10.7.2)

-- Matt

[Andrew]

I am trying to work out which is the best online backup site. Used to use LiveDrive on PC but on Mac it was memory and CPU hungry.

Just tried Carbonite and it seems to use a lot of CPU - it is doing the initial backup but when I leave computer, after a few minutes the fans kick in. Cant be doing with that all the time!

I hear that Backblaze is better for CPU and memory usage. But then I read your article. Sounds like your fix, fixes the problem so going to give it a go.

Thanks

[jordan314]

Thanks for this! I'm a new Backblaze user and was having the same problem.

[Michael DiStefano]

Thank you so much for posting this! It had been driving me nuts since installing Backblaze.