In Windows Task Manager, in the Processes tab, what does I/O Other mean

I typically use a combination of two tools when I doing this.

First Process Explorer, which is basically Task Manager on crack. I really don't know why Micorsoft doesn't just replace one for the other. this application will tell what processes are running, whether they are a sub process of another, who the owner of the process is, what files are in use by that process, the time in which it started, its path, etc. There is very little that this tool won't tell you from a basic level. It even has built-in Google searching for looking up further info on the internet about a process.

Second is the Process Explorers close cousin, Process Monitor. Process Monitor is similar to process explorer, only it shows you much more verbose information about what a process is doing. This tool will show what files and registry keys a process is try read/delete/modify, what is being written to registry/file system whenever changes are made. Because this one is so much more verbose, I have to warn you with caution that if you are trying to use it on a older/weaker computer as it may crash the system do to system overload. You can however apply filters to help limit the amount of input which comes out of it, which is probably the preferred way since this tool really shows you too much when the view is not filtered to hide whatever is not related to your troubleshooting.

The "Page Faults / sec" counter for each instance under the "Process" object (i.e. each process running on the box) is going to tell you which processes are creating the page faults. You can see the page faults with "Task Manager" by turning on the "Page Faults Delta" column, as well.

The problem with "Page Faults / sec" is that it includes both hard and soft (that is, page faults where the page needed is still in physical memory) faults. Soft faults aren't expensive.

You really want to see whether you're having a significant number of hard page faults (that is, page faults that have to go to the disk) or not. Watch the "Pages Input / sec" counter in the "Memory" object to get a feel for how many hard page faults are occurring.

Hard page faults occur when the memory page needed to fulfill the request must be read from disk. The "fix" for hard page faults is to add physical RAM.

Soft page faults occur when an application first writes to a new page (copy on write), asks for a page to be zeroed, or accesses a page that's already elsewhere in memory (like a memory-mapped file being used by another process). You probably can't do a lot to "fix" it if you're seeing a lot of soft page faults, but you shouldn't be too worried about them either.