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User profile for user: elagache
elagache Author
User level: Level 1
8 points

How to throttle down the mds daemon?

Dear OS-X gurus,


I recently "upgraded" to a 2011 MacBook Pro and a Solid State Drive. I'm stuck with running Snow Leopard to continue to run a PowerPC based application. Shortly after this upgrade, I noted that the CPU fans would run wildly whenever I left the computer idle. A little troubleshooting quickly uncovered that the spotlight indexing daemon was running up the CPU load. I assume the problem is caused in part by the high-speed file access on the SSD.


This computer is in a bedroom and the fan noise is quite annoying. Hunting around on the Internet I found two blog entries that described modifying the com.apple.metadata.mds.plist file so that the mds daemons would run at the lowest priority:


http://newartisans.com/2008/04/run-the-spotlight-indexer-at-a-lower-priority/


http://thegreyblog.blogspot.com/2012/04/is-mdworker-jeopardizing-your-resources. html


I succeeded in modifying my com.apple.metadata.mds.plist as suggested and this does help. At least at night, the fans rarely disturb me. However, during the day, very offen I'll return to my computer to find the fans running at full power once more. I would very much like to further "clip the wings" of the mds daemon to prevent this unnecessary extra effort. My computer runs 24/7 in order to collect data from a weather station, so there is more than sufficient computing opportunties throughout the day to complete the spotlight indexing.


I have read up on the options of launchd and in particular noticed the SoftResourceLimits and HardResourceLimits controls. I was hoping to limit the resources of mds enough to reduce CPU use, but I couldn't see any obvious way to use those controls to accomplish this.


Does anyone have a clever suggestion on how to throttle down the mds daemon so that this annoyance with my MacBook Pro could be minimized?


Thanks in advance for any wisdom you'all might have,


Cheers, Edouard

MacBook Pro, Mac OS X (10.6.8)

Posted on Jan 21, 2014 3:58 PM

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User profile for user: Eric Root
Eric Root
User level: Level 10
684,039 points

Posted on Jan 22, 2014 10:24 AM

Try a SMC reset. The article covers when this is required, but doing this will not affect anything.


Reset SMC

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User profile for user: elagache
elagache Author
User level: Level 1
8 points

Jan 22, 2014 1:30 PM in response to Eric Root

Dear Eric and OS-X gurus,


Thanks for the suggestion. I had some trouble getting the SMC to actually reset. I'm not sure if the instructions you gave me worked or this alternative suggestion for the 2011 MacBook Pros.


https://discussions.apple.com/thread/2718879?tstart=0


Either way, the recipes weren't entirely accurate. Using either technique, my MacBook Pro restarted after the keys where held down and released. The recipes insist you should invoke the key-sequence and press the power-on key a second time to start the Mac. Also, I read on other forums that the period to wait is longer than prescribed by Apple, which I tried. Nonetheless, after the procedure, it seemed that my fans were behaving better.


Alas, I am still coming to my computer and catching it with the fans running rather hard. Checking the previous CPU load, it seems justifed because there was a steady process going that stopped the instant I moved the mouse. So I remain suspicious that the mds daemon is making my computer work harder than it really needs to.


So if anybody has another idea on how to actually reign in the mds daemon, please do suggest!!


Thanks again for the help!


Cheers, Edouard

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User profile for user: elagache
elagache Author
User level: Level 1
8 points

Jan 25, 2014 1:33 PM in response to Eric Root

Dear Eric and Apple OS-X gurus,


Well, it wasn't as simple as that one support article, but I think I've hunted down the suspect.


For starters, I goofed when upgrading from a 2009 MacBook Pro to a refurbished 2011 MacBook Pro. I had bought a nice Solid State Drive and obviously swapped that into the newer Mac. I then tried booting and - it worked! It was still the wrong thing to do though. Part of my problem was that OS-X wasn't controlling the fans correctly. So, I erased the drive, Installed Snow Leopard from the 2011 install disk, and then restored my hard drive from the Time Machine backup. Now the fans were modulating more as I expected.


Alas, that didn't solve the mysterious fan activity when the the computer was idling. In frustration, I used the UNIX launchctl command to disable mds since it seemed like the most likely culprit. However the fan acitivity continued, so mds was off the hook. That lead to a search for a rogue application that would run only when the computer was idle. So I changed my display settings to so that the display wouldn't sleep, started Activity Monitor and waited in ambush!


The unexpected rogue: the Postbox email application (a commercial variant of Thunderbird.) It appears that Postbox is attempting to reindex my copious email archive during idle times. Even "renicing" Postbox doesn't prevent the CPU load to increase to the point that the fans kick in during the day. However, I compared the CPU activity graphs during those idle periods to the CPU load when explicitly indexing a modest-sized folder and they are very consistent. Therefore, I assume this is a temporary phenomena which will work itself out over time.


Thank you Eric for the help!!


Cheers, Edouard

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How to throttle down the mds daemon?

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