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omgwtfbyobbq

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Registered: 2006-07-04

Posts: 226

Linux equivalent of safely removing a usb device in windows?

I'm trying to get a wireless usb stick working well, and the last stumbling block I have is getting it to shut down (in a way) on a restart. If it doesn't it won't reinitialize properly, and I'll have remove it, then reload ndiswrapper, and plug it back in again. Windows automatically does this somehow, but I'm not sure what the linux analog would be.

dunz0r

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From: Sweden

Registered: 2009-03-30

Posts: 258

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Re: Linux equivalent of safely removing a usb device in windows?

You might try setting up a udev rule for it.

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graysky

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From: :wq

Registered: 2008-12-01

Posts: 10,696

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Re: Linux equivalent of safely removing a usb device in windows?

Gnome does it for you but I'm thinking that you're not using Gnome.

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omgwtfbyobbq

Member

Registered: 2006-07-04

Posts: 226

Re: Linux equivalent of safely removing a usb device in windows?

I can use gnome np, or if I can modify the udev rules that's fine too, just point in the right direction.

yngwin

Member

Registered: 2009-05-08

Posts: 67

Re: Linux equivalent of safely removing a usb device in windows?

umount

icarus-c

Member

Registered: 2009-11-12

Posts: 17

Re: Linux equivalent of safely removing a usb device in windows?

note that omgwtfbyobbq is asking about  usb wireless adapter, but not usb flash drive...
and yea,  udev is the way to go

omgwtfbyobbq

Member

Registered: 2006-07-04

Posts: 226

Re: Linux equivalent of safely removing a usb device in windows?

What would a udev rule do in my case? I can't seem to figure out how to turn it off (the kernel power stuff doesn't support suspending the device), so can udev perform the equivalent of safely removing it in windows somehow?

Mohandas

Member

Registered: 2010-08-08

Posts: 4

Re: Linux equivalent of safely removing a usb device in windows?

Try something like :
sdparm --command=stop /dev/sdX

Last edited by Mohandas (2010-08-20 13:06:58)

parintachin

Member

Registered: 2009-05-25

Posts: 72

Re: Linux equivalent of safely removing a usb device in windows?

try eject /dev/sdx works also for flashdrives not just cd's plus the hardware-cache is flushed befor the device is unmounted and ejected

o1911

Member

From: Hobart, Australia

Registered: 2009-04-28

Posts: 106

Re: Linux equivalent of safely removing a usb device in windows?

Perhaps take a look at 'pmount' - it's meant for user-based permissions mounting.

However, I think this doesn't work for sata/esata drives... if that's the case, then what's a safe way to remove these drives without root and/or gui?

Last edited by o1911 (2010-08-21 02:21:21)

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ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,349

Re: Linux equivalent of safely removing a usb device in windows?

I think I speak for the OP.  I have wondered about this for some time.  On every Linux I have encountered, unmounting a USB thumbdrive does dismount the device, but leaves the annunciator on the device illuminated. 

Certain other operating systems from the US Pacific Northwest manage to turn off the annunciator providing positive feedback that it is safe to unplug the device without the risk of corrupting it.

I had never seen Mohandas' suggestion so I tried it:

ewaller@odin:~/devel/wxwidgetsprojects/spacewar 1181 %sudo sdparm --command=stop /dev/sdb 
    /dev/sdb: SanDisk   Cruzer Mini       0.1 

The light blinked, but stayed on.  I verified it is truly unmounted.

How does one truly know when the drive has finished all of its house keeping? (Hint that can be thousands of milliseconds after the sync and dismount)?

edit: fixed typo

Last edited by ewaller (2010-08-21 04:50:07)

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o1911

Member

From: Hobart, Australia

Registered: 2009-04-28

Posts: 106

Re: Linux equivalent of safely removing a usb device in windows?

You could try lsusb.

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falconindy

Developer

From: New York, USA

Registered: 2009-10-22

Posts: 4,111

Website

Re: Linux equivalent of safely removing a usb device in windows?

I'm trying to get a wireless usb stick working

note that omgwtfbyobbq is asking about  usb wireless adapter, but not usb flash drive...

Wireless. Network device. Not a storage device.

You might see if you can turn it off via a utility like rfkill.

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cubeist

Member

Registered: 2010-08-01

Posts: 36

Re: Linux equivalent of safely removing a usb device in windows?

umount is safe to use most of the time.  It will perform necessary housekeeping and unmount the drive, however, it does not cut off the power to the drive (which is why most USB sticks will still have an illuminated led).  You can use dmesg to ensure the USB is actually dismounted and it will show a message like: usb 2-6: USB disconnect, address 2

Safely remove drive, as I understand it, is just umount with a power kill command.  So after the drive is unmounted it kills the USB power and the drive cannot be mounted unless it is unplugged and plugged back in.

The reason most computer OS's have 'safely remove drive' is because many USB controllers (the chip on the USB drive) have a persistent remount feature.  If you don't kill the power to the darn thing it will start broadcasting the initialization handshaking sequence again...which will probably be ignored by the OS since, ironically, the computer thinks the hardware space the USB drive is broadcasting from has already been allocated.  At this point most users yank the USB drive out of the socket leaving the device in a non-clean state (remember the drive started to handshake with the computer and was waiting for a reply). 

however, my knowledge on this stuff is from several years ago, so things may not function the same way today

Last edited by cubeist (2010-08-21 18:51:31)

capoeira

Member

From: Vila Velha - Brasil

Registered: 2010-05-25

Posts: 470

Re: Linux equivalent of safely removing a usb device in windows?

as I use dolphin to mount I use it to unmount, too

Roline

Member

From: Netherlands

Registered: 2009-12-05

Posts: 207

Website

Re: Linux equivalent of safely removing a usb device in windows?

try terminal

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omgwtfbyobbq

Member

Registered: 2006-07-04

Posts: 226

Re: Linux equivalent of safely removing a usb device in windows?

The problem is that it only shows up as a usb storage device in windows. In arch, there's no /dev/sd* besides my hd partitions at /dev/sda*, so I can't unmount it in that context. rfkill list doesn't pick it up unfortunately, but thanks for the ideas everyone!