How to measure individual disk activity...?

Question

How to measure individual disk activity...?

Hi all,

I have one internal HDD, "Macintosh HD". I also have some external drives that are used for Time Machine backup.

I would like to measure disk activity per disk. That is, I would like to be able to see what the "data" and "io" activity is that Activity Monitor report but per disk (Activity Monitor gives a cumulative average across all devices).

I am happy to use the Unix shell command set. Just throw it at me. Actually, I'd prefer to have the detail that the good ol' Unix shell commands provide.

Thanks in advance,

Posted on Nov 27, 2019 2:50 PM

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Answer 1

macjack

Level 10

111,242 points

Nov 27, 2019 3:03 PM in response to Community User

The command "iostat" may give you what you need.

man iostat for the manual page.

Also you may be interested to have a look at the free GUI Drive DX:

https://binaryfruit.com/drivedx

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Answer 2

dot.com

Level 4

2,455 points

Nov 27, 2019 3:00 PM in response to Community User

Take a look at "man iostat" -- has lots of options and shows some examples. If that isn't enough, then Google is your best buddy.

Good luck...

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Answer 3

dot.com

Level 4

2,455 points

Nov 27, 2019 3:35 PM in response to Community User

Well, bing is certainly a "search" service but Google has a lot more content that it searches in my opinion, and almost always gives much more results. I assume you searched for "iostat" not instate...I searched for "how to measure disk io on mac from command line" and that is what led me to the link I searched...came up with over 10 screens of possibles...i merely looked at a few and picked what I considered a good one...and then tried to condense that down to simply use "man iostat".

Good luck...

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Answer 4

dot.com

Level 4

2,455 points

Nov 28, 2019 9:05 AM in response to Community User

I completely agree about how good Unix/Solaris/BSD/ATT/etc feels -- it gets in your bones and refuses to leave no matter how long between meals and just makes you feel good all over whenever you dive in to use it ;-)

Another good thing to use as a tool to see what is happening is the "Activity Monitor" in /Applications/Utilities -- you can list all processes from all users and has screens specifically for CPU, memory, disk, network so makes it handy depending on what you want to do. Unfortunately it doesn't let you drill down and get details that the command line stuff will expose.

Good luck...

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Answer 5

Nov 27, 2019 3:26 PM in response to Community User

Thank you both. I got it. Believe it or not, my "Google" search (actually it was Bing) yielded nothing on instate. I got a lot of nonsense about old Linux versions. So thank you. I'm on my way to monitoring and figuring out what processes are using which disks and why....

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Answer 6

Nov 27, 2019 3:44 PM in response to dot.com

Well, actually, I searched for something like "how to measure disk activity" or something like that. I admit sheepishly that, despite being an old Unix system programmer (years ago) I couldn't remember the iostat command, which now believe was the same on Solaris. But all is good. I'll now go back and look at how to take the process names and correlate them to the particular disk activity I want to monitor.

This research started when I noticed RTProtectionDaemon (I have the Premium version of Malwarebytes) was running for very long periods of time, not taking too much CPU but definitely affecting disk performance. I could see the disk access light on my iomega external drive blinking but not the Western Digital external drives nor the internal Mac hard drive.

I feel like I'm back in the good ol' days once again....

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Answer 7

Nov 28, 2019 3:26 PM in response to dot.com

Thanks much, dot.com. Yep, I'm still an engineer at heart despite working as an enterprise architect for many years now.

Use the right tool for the job. Despite the usefulness of GUI tools, sometimes there is just no substitute for the wealth of shell-based commands in any of the Unix-based systems.

;-)

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How to measure individual disk activity...?

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