How can I get I/O stats for a particular disk in OS X?

May 9, 2010 9:31 AM

How can I get I/O stats for a particular disk in OS X?

Activity Monitor will give total I/O stats for all disks, but I just want to know how much is being read/written to a particular disk.

Thanks!

posted by mpls2 to computers & internet (11 answers total)

Open Terminal.app and type 'iostat',
posted by doteatop at 9:45 AM on May 9, 2010

Thanks doteatop, but I was hoping for something more user friendly.
posted by mpls2 at 9:53 AM on May 9, 2010

Open the Apple utility "Activity Monitor" and select Disk Usage or Disk Stats.
posted by zippy at 10:02 AM on May 9, 2010

Oh D'oh, I didn't see the second line of your question, and only Disk Usage (space free) lets you select a disk
posted by zippy at 10:04 AM on May 9, 2010

Um...not to be sarcastic here, but...what's your idea of user friendly? My iostat output looks like

disk0 cpu load average
KB/t tps MB/s us sy id 1m 5m 15m
31.25 1 0.04 0 0 100 0.11 0.05 0.01

And the man page explains

The standard iostat device display shows the following statistics:
KB/t kilobytes per transfer
tps transfers per second
MB/s megabytes per second

So this particular machine averages 31k transfers once a second with an overall throughput of 0.04 MB/s (i.e., nothing at all). You're really not going to get any clearer than that unless the program just lies (which Activity Monitor does---google for the "massive VM size" bug).
posted by d. z. wang at 10:42 AM on May 9, 2010 [1 favorite]

zippy: "Disk Usage (space free) lets you select a disk"

Also, maybe zippy is thinking of df? The disk usage program is du, and it lets you choose by directories (which, of course, can be used to get usage of a disk, but df is much easier for that).
posted by d. z. wang at 10:44 AM on May 9, 2010

One of the first things I install on a Mac is iStat Menus, which lets you monitor many things including individual disk activity.
posted by caaaaaam at 10:53 AM on May 9, 2010

dz: user friendly is something that doesn't involve typing. I'd like to be able to get this info at a glance, or with a single click, and I'm more interested in total values vs transfer rates.

caaaaaam: yup, i have iStat menus, but that sadly doesn't have what I'm looking for.
posted by mpls2 at 12:41 PM on May 9, 2010

Also, maybe zippy is thinking of df?

Nah, I was referring to the Disk Usage tab of the Activity Monitor app.

Also, 'iostat -I' reports totals.

Is it possible to invoke iostat via AppleScript or Quicksilver?
posted by zippy at 1:41 PM on May 9, 2010

Ah, double strike-out then.

zippy: "Is it possible to invoke iostat via AppleScript or Quicksilver?"

Try GeekTool (tutorials from Lifehacker tutorial and ThemeMyMac, lots of scripts at the MacRumors forums).
posted by d. z. wang at 2:52 PM on May 9, 2010

mpls2: Ah, sorry, I missed "total". GeekTool looks like it'll get the job done.
posted by caaaaaam at 8:59 PM on May 9, 2010