What program is reading my CD/DVD/Blu-Ray drive in my external drive?

Question

I have two external USB optical drives, both burners, one that will work with DVDs and CDs, the other that will also handle BDs (Blu-ray Discs). I use these sometimes with MakeMKV. Recently I had an issue with reading a BD with MakeMKV and had to force-quit MakeMKV. I tried to eject the BD, but Disk Utilities would not because it was in use. (I remember at one point I found a way to still eject it, but I was unable to use that drive to read anything until I rebooted because the OS still saw it as in use.) I rebooted.

On reboot the OS recognized the BD in the drive and it came up in Finder. But I still heard a fair amount of activity from the drive. It's no longer making noise, but the access LED on the drive is still flashing. I've had this happen before, where I have discs in either drive, usually DVDs or BDs, and I hear movement in the drive even when I haven't been using any software to access that drive for hours or even a day or more. So it seems that something is accessing my external USB optical drives even when I'm not using any software to do this.

How can I find out what program is trying to access discs in my optical drive?

Answer 1

If you're comfortable with the command line, you can open a Terminal window and use a command like:

lsof +D /Volumes/<volumename>

‘lsof’ stands for ‘list open files’, and lists information on files opened by processes.

It can take a very long time to run (as it has to list all files on the given volume and then search for processes using any of them).

It includes only files your user has permission for, so you may want to prefix it with sudo , to run it as root.

By default it lists the command name, process ID, username, file descriptor number, device numbers, file size, node number, and filename — but there are options to show other info. (Type man lsof to see info on all the various options.) The command name is probably the most useful item here; though if that's not enough, you can note down the process ID and look that up in ps or the Activity Monitor app.

(You don't need to search an entire volume, as that command will work with any file or directory; the fewer files it has to search for, the faster it'll run.)