USB device activity when not mounted

Thomas Mueller mueller23 at
Fri Jun 15 09:26:17 UTC 2012

> I can understand why I would see activity on a USB device when it's first plugged in.  But why do I see continued activity (i.e. the light blinks on a usb disk or memory stick)?  When I umount one of these, they keep being beat up on and it makes me nervous...  At what point is it sync'd and safe to unplug?  I assume when the umount returns, but what's going on after that?

> Gary

I had that problem/quirk with a SanDisk Cruzer 8 GB USB stick. 

Light would slowly blink in all OSes (FreeBSD, NetBSD, Linux) I use, but not in FreeDOS.  This even happened before mounting and persisted after umounting.

I just tested on the new computer, running FreeBSD 9.0-STABLE #10 amd64, got the slow blink even without mounting.

No other USB sticks ever did this in my experience, though I can't speak for brands I've never used.

USB sticks are not all created equal.  One lot of Kingston Data Travelers would not work in NetBSD but were good in Linux and FreeBSD, and even FreeDOS and OpenIndiana on the new computer. Other USB sticks, including Kingston Data Travelers, worked in NetBSD as well as Linux and FreeBSD.

But I was not able to install OpenIndiana on the new computer because it couldn't access a GPT-partitioned hard drive, neither could FreeDOS.


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