Windows – How to find out why the computer is thrashing its drive

hard drivewindowswindows-vista

I booted up today and my disk hasn't stopped thrashing in 20 minutes. CPU activity is flat; the only processes using anything right now are firefox and dwm.exe and it's ~1%. So I figured I'd look at what's happening with Procmon.

svchost.exe is making thousands of requests per second. It looks like something or the other is running an install, because it checks HKLM\System\Setup\SystemSetupInProgress every few milliseconds. It's also looking at files in C:\Windows\System32\wbem\repository a lot; I presume that's WMI queries. Everything else looks like random hard drive queries (for example, it looked for "close.WAV" in 7 or 8 program files directories.

I want whatever it is to STFU and stop thrashing my hard drive (since starting this post it sounds like it's calming down.) But since it's hiding in svchost.exe, it's pretty hard for me to tell it to calm down. The Event Viewer doesn't seem to indicate much, though there's about 15 failures that seem to hint it tried to install some automatic updates. I set my computer to ask before installing them; I'm not sure why it'd do this.

Why is there not a "WTF are you doing?" button? Why is it so easy for a process to perform hard drive olympics while I have nothing to do but sit back and hope it's for the better? Is there any way to figure out exactly what's going on when this happens?

Best Answer

From my Post on What’s making my disk thrash in Windows XP?

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!

Related Solutions

Disk Thrashing – How to Reduce Disk Thrashing (Paging) in Windows

Mark Russianovich has written a good long article on Virtual Memory,
Pushing the Limits of Windows: Virtual Memory

Virtual memory separates a program’s view of memory from the system’s physical memory, so an operating system decides when and if to store the program’s code and data in physical memory and when to store it in a file. The major advantage of virtual memory is that it allows more processes to execute concurrently than might otherwise fit in physical memory.

While virtual memory has limits that are related to physical memory limits, virtual memory has limits that derive from different sources and that are different depending on the consumer. For example, there are virtual memory limits that apply to individual processes that run applications, the operating system, and for the system as a whole. It's important to remember as you read this that virtual memory, as the name implies, has no direct connection with physical memory. Windows assigning the file cache a certain amount of virtual memory does not dictate how much file data it actually caches in physical memory; it can be any amount from none to more than the amount that's addressable via virtual memory.

It is a very good read.

How Big Should I Make the Paging File?
Perhaps one of the most commonly asked questions related to virtual memory is, how big should I make the paging file? There’s no end of ridiculous advice out on the web and in the newsstand magazines that cover Windows, and even Microsoft has published misleading recommendations. Almost all the suggestions are based on multiplying RAM size by some factor, with common values being 1.2, 1.5 and 2. Now that you understand the role that the paging file plays in defining a system’s commit limit and how processes contribute to the commit charge, you’re well positioned to see how useless such formulas truly are.

Earlier article: Pushing the Limits of Windows: Physical Memory

You can see physical memory layout with the Meminfo tool by Alex Ionescu.

Hard Drive – Why Cycle Count Increases Rapidly

These values you got from man hdparm apply to -S option – spin-down, making platters stop rotating.

My quick research indicates that Load_Cycle_Count is connected to parking heads and it seems the -B option (Advanced Power Management, APM) is the right one. The description in the man page is not perfectly clear to me but your value of 128 is the most aggressive one that doesn't permit spin-down. My guess is it parks the heads most often.

You calculate a spin-down time from this value of 128 using the description of -S and I think it's wrong. This calculation confuses -B and -S. The same confusion occurs when you set APM to 241.

I've seen claims that hdparm -B 255 /dev/sdX helps. It disables Advanced Power Management though. My disk is set to 254 and it has what I think is a moderate Load_Cycle_Count with respect to Power_On_Hours: 200k and 20k respectively, so the ratio is way better than yours.

My advice is to use one of the following:

hdparm -B 127 /dev/sdX
hdparm -B 254 /dev/sdX
hdparm -B 255 /dev/sdX

I guess if you set -B to a value that permits spin-down (i.e 127 or less) then you should also adjust -S option to get not-too-short spin-down time. This is because every spin-down requires heads to be parked.

While man hdparm warns about various dangerous options, -B is not among them. Even if I'm completely wrong it should be safe to experiment.

Best Answer

Related Solutions

Disk Thrashing – How to Reduce Disk Thrashing (Paging) in Windows

Hard Drive – Why Cycle Count Increases Rapidly

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