The disk activity monitor charts show blue line, green line with the green shaded area below and sometimes also the orange line. Of course, the higher the lines the more the activity and horizontal axis is clearly the time but what is exactly plotted there? I have looked into disk activity monitor help but did not find the legend of these charts there.

I mean, Resource Monitor, Disk tab, charts on the right.

  • 3
    I find it quite deplorable that the help does not explain the diagrams, or buries it so deep that it cannot be found. Jul 12, 2017 at 9:11

2 Answers 2



Many thanks to RoG below for more clarification on this answer:

Green is data being WRITTEN TO and READ FROM the drive.

Blue shows a statistical quantifier of the amount of data that has been written to and from from the drive, as explained by RoG below:

"...Blue...showing the current value of the green line divided by the maximum value of the green line, as a percentage."

Orange shows the impact of a specific task, as chosen by checking a box to highlight the task on the left of the window.

  • I'm fairly sure that this is incorrect, see my answer. It can easily be shown that writing a large file to disk increases the blue line also.
    – RoG
    Sep 15, 2017 at 7:28
  • @RoG Hi, I thought the blue line increased because files are read immediately as and after they are written to verify the files and also to add them to various indexes. I have checked the TechNet article you link to and you are right, but it is not very clear. technet.microsoft.com/en-us/library/…
    – Matthew
    Nov 11, 2017 at 13:05
  • Good that you corrected your answer, and referenced mine multiple times, but I think the correct thing to do is to delete the incorrect answer in this case. Not a big deal though. Cheers.
    – RoG
    Nov 13, 2017 at 12:51

According to Microsoft TechNet:

Disk displays the total current I/O in green, and displays the highest active time percentage in blue.

Notice that this corresponds to the Disk Activity list on the left (might need to expand it), which shows "XX KB/sec Disk I/O" and "XX% Highest Active Time". So, I interpret this as green being both reads and writes, and blue also being reads and writes, but showing the current value of the green line divided by the maximum value of the green line, as a percentage.

Admittedly my source is for Windows Server 2008, not Windows 7.

The orange line shows I/O for a specific task, enabled by checking a box in the "Processes with Disk Activity" list on the left (might need to expand it also).

  • Hi, whoa, mind blown!
    – Matthew
    Nov 11, 2017 at 12:52

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