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Old Feb 6, 2012, 08:02 AM   #1
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Disk Activity overload! Slowing my iMac from an unknown source?

Hi guys. I own the high-end iMac 21.5 for about 10 months now. Absoloutley no problems with it until yesterday, when everything slowed down as I did tasks like browse firefox and even getting the beachball from just going to the dashboard. Im not a heavy user, I just web surf, and watch videos etc ..... I thought this would correct itself by restarting my machine, but the iMac took within 5 mins to load up (previous day and within the last 10 months it only took 1 min), and the sound from the harddrive looked as if it doing overtime.

I checked the activity monitor and results below. Seems data writtern/read is working a fair bit. Does anyone know what might be the cause of this? (im running lion).

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Old Feb 6, 2012, 08:21 AM   #2
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That activity might be quite normal, if you don't have enough RAM and contents of it have to be copied (swapped) to the HDD.
It can also be log files and temporary cache files, that are created during normal use.
You can check via Terminal to see, that you have quite an active disk life.

In Terminal you need to enter this:
sudo fs_usage
Enter the admin password password (no worries, that no characters appear in the Terminal window, that is a normal Unix behaviour) and now the Terminal is listing lots and lots of data and showing you which process does read or write to the HDD.
You can stop this listing via pressing CTRL+C.

Here is a more detailed article about the fs_usage command: Watch file system activity in real time

Last edited by simsaladimbamba; Feb 6, 2012 at 08:42 AM. Reason: no need for the root user
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Old Feb 6, 2012, 04:08 PM   #3
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Originally Posted by Zelnaga View Post
I checked the activity monitor and results below. Seems data writtern/read is working a fair bit. Does anyone know what might be the cause of this? (im running lion).
Change "My Processes" at the top to "All Processes". Then click on the System Memory tab at the bottom and post another screen shot. If a drive is constantly active or your CPU utilization is high (possibly with increased temps and fan speed) when you're not running any apps, check to see if Spotlight is indexing by looking at the Menu Bar icon: (not indexing) (indexing)
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Old Feb 24, 2012, 10:01 AM   #4
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possible disk activity solution

You may have already figured this out, but I just happened upon this after resolving on my system, so figured I'd share the fix that worked for me. I noticed VMware on your Activity Monitor list. In my search, I found that many people were able to resolve the problem by dragging their Bootcamp partitions into the Privacy area of Spotlight (in System Preferences) - Spotlight (more specifically the mdworker function) goes nuts trying to index the Windows partition, which isn't possible since it's closed. So I decided to see if that goes for virtual Windows volumes as well, so I dragged my virtual machine volumes (had an older vmware volume that I haven't tossed yet, plus a newer Parallels volume) into Privacy in the Spotlight settings so they'd be off-limits for indexing, and now my 6-core is flying again, no more constant disk activity bogging it down. So might be worth giving that a try - good luck.

Last edited by inmania; Feb 24, 2012 at 02:56 PM.
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Old Feb 24, 2012, 01:57 PM   #5
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I actually had a very similar issue with my MBP. I tried everything in the books but got nothing. When I ran a HDD benchmark, I could only get around 20MB/s read and write speeds. Beach balls everywhere.

I ended up backing up my drive and wiping it to start fresh. So much faster now. HDD benchmark now reads 70MB/s and next to zero beach balls. I know it's kind of a last resort, but it does work.
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Old Apr 4, 2014, 06:40 AM   #6
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Thanks to simsaladimbamba - for the "sudo fs_usage" tip.

I discovered that Google Chrome was killing my hard disk (I think the Google Calendar module is badly written - Overall, I think Chrome tries to be too fracking smart and do too fracking much).

Killed Google Chrome, and now the system / hd usage back to normal.


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