help; inexplicable hard drive activity

[FredAkbar]

Hi all. Lately, for lengthy periods of time, my Intel iMac (see sig)'s hard drive has been making whatever sounds hard drives make (you know, the usual kind) for no apparent reason. It will go for a while and then stop. I thought maybe it was because of Parallels, but I uninstalled that and the problem persists. I even reinstalled OS X but the problem has returned.

I have Activity Monitor open and sorted the list by CPU and the only things using any CPU at all are things like pmTool, kernel_task, mds, launchd; that's about it besides actual apps I'm using, like Firefox and Adium, but quitting those never solves the problem.

I don't think it noticeably slows down the computer, since Activity Monitor isn't showing anything using much CPU at all (sorting the list by RAM usage doesn't help either; the most RAM being used is by kernel_task, 100 megs or so of real RAM), but it kind of worries me, and it probably heats up my computer more than I'd like.

Any ideas about what this could be or how I could find out?

 

[plinden]

You are probably just noticing the Mac swapping to disk. Take a look at Activity Monitor/System Memory. Is "page outs" high, in the 10s - 100s thousands?

It probably started doing it more with Parallels so that you noticed it, but then you can't help noticing it now.

 

[FredAkbar]

My VM size is 7.85 GB and my page ins/outs are about 70000/0 (uptime is about 25 hours). What's the difference between page ins and outs? One is swapping to the hard drive, and one is reading back from it into RAM, right?

But why would it do it so suddenly and for so long at a time, when I'm hardly doing anything (just chatting/browsing, if anything at all)? Especially with 2 gigs of RAM.

update:

It started doing it again so I looked at the Disk Activity tab of Activity Monitor.
Reads in: 56594
Writes out: about 6 million
Read in/sec: 0
Writes out/sec: 68
Data read/sec: 0 bytes
Data written/sec: 288.00 KB

In the memory tab, page ins/outs hasn't changed at all, so I don't think this is a memory thing.

The CPU tab shows almost half my CPU being used by "User" processes, but these aren't showing up in the list of processes. What gives?

edit: to give an idea of how long this is going on, it has been going for the past 5-10 minutes at least, nonstop, with me doing absolutely nothing except sitting here watching Activity Monitor. It has been consistently writing data to the disk at around 280 KB per sec.

one last update for the night: after restarting, the hard drive stopped, as always, and Activity Monitor showed that disk writing had returned to 0 KB/sec.

Also, I logged in as root (by the way, the hard drive stuff keeps on going even if I log out; only a restart stops it) and used TinkerTool to show hidden files, and I sorted my hard drive's contents by Date Modified, and some invisible DS_Store files had been updated within the last minute. Aren't these used for indexing? I considered Spotlight indexing as a source of the problem, but that usually happens on the fly, from what I understand; it wouldn't need to arbitrarily index for tens of minutes at a time.

 

[FredAkbar]

I may have figured it out. I ran sudo fs_uage in Terminal while the writing was going on, and I saw a bunch of messages with "samba" in them. I went into the Sharing pane of System Prefs and turned off Windows Sharing, and the sound immediately stopped. Now let's see if it stays stopped.

[edit: for the record, yes it did stay stopped; as imacintel's post below says, Windows sharing apparently creates lots of HD activity for whatever reason]

 

[imacintel]

I was just about to post"turn off wondows sharing". It really takes a big toll on your HD.