USB device activity when not mounted
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. Tom ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: USB device activity when not mounted
On 06/15/12 03:23, Thomas Mueller wrote: 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? I had that problem/quirk with a SanDisk Cruzer 8 GB USB stick. Heh. My 4 gig one does it too. However, so does my seagate usb hard drive, so it's not specific to one mfg. On 06/14/12 07:49, Daniel Feenberg wrote: Is it possible that there is volitile memory buffering in the stick that may not have been written to flash when umount thinks it is complete, and the flashing light is an indication that power is still required to complete the write to non-volitile memory? I'm pretty sure that's not it. My devices (memstick and usb disk) will blink happily for hours. Well, minutes, anyway. I haven't got the patience to wait it out beyond that... ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: USB device activity when not mounted
Polytropon wrote: On Wed, 13 Jun 2012 22:26:16 -0600, Gary Aitken wrote: 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? I don't think that's a problem. I've got a USB stick here that has a blinkenlight as soon as it's powered on (plugged in), even if there is no reading / writing / mounting activity. After you've successfully performed umount, the USB stick _is_ synced and can safely be removed, no matter what you assume the funny lights want to tell you. Maybe that's just a modern feature to make the USB stick more entertaining. :-) I think der Blinkenlights is a Windows thing - some Windows driver bit turns it on and off. When you click the 'safe to remove' thing it's supposed to turn it off to tell you it's OK to pull it out. Totally meaningless and useless 'feature' if you're not using Windows, aside from the entertainment. :-) -Mike ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: USB device activity when not mounted
On Thursday 14 June 2012 07:05:11 Polytropon wrote: I don't think that's a problem. I've got a USB stick here that has a blinkenlight as soon as it's powered on (plugged in), even if there is no reading / writing / mounting activity. After you've successfully performed umount, the USB stick _is_ synced and can safely be removed, no matter what you assume the funny lights want to tell you. Maybe that's just a modern feature to make the USB stick more entertaining. :-) I have a Kingston one here which does appear to only blink while data is being transferred but one thing I have noticed is that the light continues to blink for a few seconds after the umount command completes. Presumably syncing is not compled until a few seconds after umount. Perhaps it's always safer to wait a few seconds after umounting before removing any USB storage device? -- Mike Clarke ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: USB device activity when not mounted
On Thu, 14 Jun 2012, Mike Clarke wrote: On Thursday 14 June 2012 07:05:11 Polytropon wrote: I don't think that's a problem. I've got a USB stick here that has a blinkenlight as soon as it's powered on (plugged in), even if there is no reading / writing / mounting activity. After you've successfully performed umount, the USB stick _is_ synced and can safely be removed, no matter what you assume the funny lights want to tell you. Is it possible that there is volitile memory buffering in the stick that may not have been written to flash when umount thinks it is complete, and the flashing light is an indication that power is still required to complete the write to non-volitile memory? Futhermore, are we sure that umount even waits for a sync? There is no mention of that in the man page and I don't recall any long waits for umount to return. daniel feenberg ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: USB device activity when not mounted
On Thu, 14 Jun 2012 09:49:00 -0400 (EDT), Daniel Feenberg wrote: Is it possible that there is volitile memory buffering in the stick that may not have been written to flash when umount thinks it is complete, and the flashing light is an indication that power is still required to complete the write to non-volitile memory? That is possible, but then, the light should be silent after a finite amount of time. Futhermore, are we sure that umount even waits for a sync? There is no mention of that in the man page and I don't recall any long waits for umount to return. If I remember correctly, the umount command instructs the kernel to write all pending file buffers and then detach the device from the file system hierarchy. When the device has been detached (doesn't appear anymore in mount output), everything should have been written. However, as you said it might be possible that _inside_ the USB stick there is still an action that needs to be performed and therefore requires power. But I doubt this takes several seconds to complete... -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ... ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: USB device activity when not mounted
On Thursday 14 June 2012 15:45:46 Polytropon wrote: However, as you said it might be possible that _inside_ the USB stick there is still an action that needs to be performed and therefore requires power. That's a possibility. But I doubt this takes several seconds to complete... I've just run a test here. The umount command returns almost instantaneously and the light, which is normally only lit while data is flowing, flickers for about 2 seconds after the umount command. But further testing showed that it flickers for 2 seconds after reading single byte file so perhaps the blinkenlight is configured with a minimum activation time. Being cautious however, I always wait a few seconds before removing any USB stick from any computer. -- Mike Clarke ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
