in Mac Apps and cloudd

If you’ve started using the new Photos app for Yosemite and you have a slighter older Mac1, you may notice your fans spinning up and your computer getting hot even though it seems like you’re not actually doing anything.

As best as I can figure out, the culprit seems to be the syncing service running in the background to keep your in sync with what you have in iCloud Photo Library.

activity monitor

I believe “cloudd” is responsible for all iCloud syncing, including the possible thousands of photos being flung from Mac to iPhone to iCloud. “” is likely doing exactly what it describes – any videos that aren’t in a compatible format for iCloud are being converted in the background while you’re trying to get other work done.

The blessing with Apple’s iCloud syncing system is that it’s all behind the scenes and there’s nothing to configure beyond checking a box and signing in with your iCloud account. The curse is that Apple’s iCloud syncing system is all behind the scenes and there’s no way to know if it’s going to be done soon or way to pause it and restart later like you can with a service like Dropbox.

I’m sure syncing is especially rough right now as millions of people are all throwing their photo libraries at iCloud at the same time. The scale of it is impressive, scary and interesting.

With iCloud Photo Library there’s one less thing to worry about backing up if you switch to a new Mac – now you can just sign in and your photos are all there ready to keep using. As long as Apple keeps building data farms to keep up.

  1. It may also happen on new Macs, I just don’t have any around to test my theory with.


  1. That’s a logic argument, but I have the same problem with one difference: I don’t have iCloud Photo Library activated, and I see the same process on the Activity Monitor. Do you have an idea about why it happens?

    Many thanks and congratulations for your blog.

  2. Which one? Cloudd? I think that’s the iCloud syncing service.

  3. It is possible to pause the upload for one day in the preferences.

  4. This process is actually generating medium and small sized videos for quick playback on any devices that are not holding your full sized library. The videos are temporarily stored here before they are uploaded to iCloud.

    Photos Library.photoslibrary/private/

    As far as I can tell the additional space does not count against you. It seems that Apple has decided it is cheaper to take up a bit more bandwidth than to do the video processing on their end.

  5. Cool. It’s interesting to figure out what all Apple is actually doing behind the scenes during the “simple” process of uploading your photos.

  6. Cool, I’d been wondering about this process. I noticed it in the beta and assumed it must’ve been doing something as described by TomK.

    It certainly slows things down on my 2010 13″ MacBook Pro with puny Core2Duo!

  7. Heh you and me both. My 2007 iMac seems like it’s trying to climb a mountain when it’s going in the background.

  8. My 2007 MBP can’t keep up either. I’m averaging about 5,000 photos a day upload. CPU is pinned regularly from the VideoConversionService and ImageConversionService.

    At least this way I don’t have to worry about blowing out my ISP quotas.

  9. Heh that’s a good point. Hadn’t thought of that angle. But if you optimize for minimal storage on your computer, original photos/videos must be headed to the cloud right?

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