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How to read Disk Activity in Activity Monitor

Hi. I understand what the different values pertain to at the bottom of the Disk Activity screen in Activity Monitor (number of times the computer accesses the HD to read and write data, and the amount of data read from and written to the disk per sec.) but I'm not sure how to evaluate them as to whether or not they're indicating a problem or less than ideal performance from my HD or if they're out of balance. Can someone give me a few pointers as to what I should be looking for?

Final Cut Pro 6, Mac OS X (10.4.11)

Posted on Dec 12, 2013 9:02 PM

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Posted on Dec 13, 2013 1:50 AM

Hello,


I think there may be other factors to look at.


See if the Disk is issuing any S.M.A.R.T errors in Disk Utility...


http://support.apple.com/kb/PH7029



Open Activity Monitor in Applications>Utilities, select All Processes & sort on CPU%, any indications there?


How much RAM & free Disk space do you have also, click on the Memory & Disk Usage Tabs.


Open Console in Utilities & see if there are any clues or repeating messages when this happens.


In the Memory tab of Activity Monitor, are there a lot of Pageouts?

User uploaded file

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Question marked as Best reply

Dec 13, 2013 1:50 AM in response to stopmotion

Hello,


I think there may be other factors to look at.


See if the Disk is issuing any S.M.A.R.T errors in Disk Utility...


http://support.apple.com/kb/PH7029



Open Activity Monitor in Applications>Utilities, select All Processes & sort on CPU%, any indications there?


How much RAM & free Disk space do you have also, click on the Memory & Disk Usage Tabs.


Open Console in Utilities & see if there are any clues or repeating messages when this happens.


In the Memory tab of Activity Monitor, are there a lot of Pageouts?

User uploaded file

Dec 13, 2013 11:21 AM in response to BDAqua

Hi. Thanks for responding again. My question about interpreting the values shown for Disk Activity in the Activity Monitor relates directly to an issue I'm having w/ my audio recording application where as my song file gets more complex w/ added tracks and processing effects, imported sounds, etc., the app. begins to halt and proceeds in a very jerky manner w/ very uneven playback and w/ audio randomly dropping out. I contacted Tech Support for my audio app and they thought the problem might be with my hard drive speed, fragmentation or free drive space. So I was trying to nail down the source of the decreased performance. Before I answer your questions, let me just mention that in the audio app. there's a window called Performance Monitor (kind of similar to Activity Monitor but on a much simpler scale) and that shows a high overload for Hard Drive performance but CPU and RAM are not being taxed at all (according to Performance Monitor).


To address your questions.

S.M.A.R.T. status is verified in Disk Utility for my Hard Drive.

In Activity Monitor, CPU% is in the 90s but sometimes going as high as 107% for my audio app. My machine is a Dual 2.3 GHz PowerPC G5.

I have 4.5 GB RAM. 3.20 GB is shown as free.

0 Page outs.

Free space on disk: 25 GB.

Yes, there is a repeating message in Console: ### Warning: Audio render: Preload segment not ready

Dec 13, 2013 2:48 PM in response to BDAqua

I believe my drive is 250 GB w/ 232.89 capacity. I'll try clearing another 10 GB to give me 35 GB of free space and see if that makes any difference.


Thanks for the link, although I didn't follow all that was being discussed on that forum and no one seemed sure what the error message meant. But I will take it up w/ Tech Support now that I am aware of it. So thanks for suggesting to check the Console.

Dec 13, 2013 3:19 PM in response to stopmotion

For what you're doing AND if it is a Disk speed problem, I'd try to keep 80 GB+ Free.


A really rough over simplified explanation might go like this...


If a drive has 10% free space, then the odds are 1 in 10 that the head will be close to where it needs to write, if it's 33% free space then chances are 1 in 3 that the head will be close to where it can write if need be. 🙂

How to read Disk Activity in Activity Monitor

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