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I have a sick Windows XP laptop; something's making the disk thrash and the entire system is sluggish to unresponsive a few minutes after boot. How do I figure out what is making the disk thrash? Task Manager is fine for finding what's using the CPU or memory, but doesn't show disk I/O.

Details: running Win XP Home, the machine was working fine until a few days ago. I've verified it's not paging because it's out of RAM. There's no scary SMART errors according to DiskCheckup.

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Do you have a virus scanner or active malware scanner running? – Troggy Aug 31 '09 at 17:39
up vote 11 down vote accepted

Download Process Explorer from Microsoft / Sysinternals.

Run it and click view > Select columns. Click on the Process Performance Tab, and select "I/O Reads" and "I/O Writes".

You can do this from Task manager, but I prefer using Process Explorer.

You can then sort by these columns and see what is doing the most read / writes.

(if using Vista / 7 remember to run as ADMIN (or click file then "show details for all processes" which will do this for you)

I tend to find that Dropbox and mesh on a few machines I support seem to run wild with read/write bytes 24/7 so if you use any sycn software, first bet is to look at that, however running this tool should tell you exactly what is wrong.

In addition, you can click on any of the graphs at the top of the screen which brings up a "System Information" dialog of historic information. One of the graphs (third one down) is "I/O Bytes", Simply hover your mouse over any of the peaks, and it will tell you what is taking up the most resources. - Exactly what you want!

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Kansas State University has an awesome 14-page handout on how to use Process Explorer, complete with screenshots (warning, PDF link):… – Jared Harley Aug 31 '09 at 17:50
Thanks! One extra tip: the "delta" views are useful for sorting on what's using the disk right now. – Nelson Aug 31 '09 at 18:24

You can set task manager to show each applications Disk I/O. Navigate to:

View -> Set Columns

this dialog will pop up, check the disk read & write i/o boxes:

alt text

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hivemind – John T Aug 31 '09 at 17:46
+1 for ZoomIt – Ian Boyd Aug 31 '09 at 18:19
thank you! +1 for an option that doesn't require extra software, but I found the Process Explorer history graph very helpful. – Nelson Aug 31 '09 at 18:26

In addition to the mentioned Process Explorer, i would try Process Monitor.

With Process Monitor you can watch file activity happen in real time; which file is being read/written, and by what process.

  • If it's only happening during startup, then it is due to everything being read off the hard-disk as the machine starts up. Use msconfig to do a startup that doesn't involve "startup items".

  • Another culprit during startup is the size of your User or Machine registry hives. Years of programs installing themselves grows the hives. Try creating another user account, log onto that one and see if it's any faster.

  • Having too many fonts installed can slow Windows' startup (e.g. Photoshop installs hundreds of fonts i know i'll never use).

The common thread is that there's just a lot of I/O happening on startup. Trim what has to be read, defragment so that Windows can take advantage of it's multiple asynchronous I/O requests, or add more RAM so it can cache more.

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My Windows Vista was thrashing more than 50% of the time. I stopped indexing and superfetch. Still churned away much of the time even when I was doing nothing on the computer. What finally fixed my problem was to...........defragment the hard drive. Since then the computer is quiet; no noise whatsoever. I've had this machine four or five years and never defragmented. When I tried to defragment it in the past it would check the disks and report tht the system was working GOOD and there was no need to defragment. That's what I got just a couple of days ago. Finally I went ahead and now the thrashing problem seems to be cured. I restarted indexing and superhost and still zero noise from the machine. Bliss!

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I would suggest getting Process Explorer and replacing Task Manager with it. With Process Explorer you can look at I/O activity as well as all the information tha task manager gives plus much much more.

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I be too slow...waaa.waa.waa...:) – EBGreen Aug 31 '09 at 17:45

As a general bit of advice, take a look at Defragmenting the drive.

(Right-click the Local Disk drive and select "Properties" and then the "Tools" tab, followed by "Defragment Now...".)

Just click on "Analzye". The thing to look out for in the report, is large fragmented files. Somoething I've come across a lot is people with fragmented Outlook PST files. They might have a 500Mb PST fragmented into 1000+ bits and when they open Outlook, the disk goes crazy picking up all the pieces.

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Procexp is awesome, but you can add disk i/o columns in the task manager. If you're not allowed to install software you can download it from their live site.

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