安全的移除U盘，移动硬盘（使系统能关闭U盘的电源）

[zenglanmu]

我的8.10U盘卸载后灯还亮，在windows下安全删除硬件后灯是灭的
论坛上也不乏这样的讨论
viewtopic.php?f=48&t=161607&p=1004336
viewtopic.php?t=26759

关于U盘卸载后灯还亮的问题，这样分析下：
U盘在卸载后虽然不挂载在文件系统上了，但还是连上电脑的，用fdisk -l就还能看到U盘的设备名，就/dev/sdx之类的。
可以说U盘的控制芯片并没认为已从系统上离开。
有的网友认为从数据安全的角度讲，这时文件读写完成了，不会对数据造成损害了。而且USB设备应该支持热插拨功能，这时U盘就能直接拔下了。但我觉得还是能把U盘的电源断开比较好
http://code.google.com/p/wdleds/wiki/Pr ... ementation
此贴分析了一下windows下安全删除硬件都做了哪些事情。linux要使U盘卸载后灯不亮还要给U盘送停止等指令才行

http://elliotli.blogspot.com/2009/01/sa ... linux.html
这个帖子作者写了一个脚本，在我的威宝U盘上试验成功。在一个80G刀锋移动硬盘上试时虽然LED灯还亮，但fdisk已经看不到了

#!/bin/bash
#
# suspend-usb-device: an easy-to-use script to properly put an USB
# device into suspend mode that can then be unplugged safely
#
# Copyright (C) 2009, Yan Li <elliot.li.tech@gmail.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# To reach the auther, please write an email to the address as stated
# above.

usage()
{
cat<<EOF
suspend-usb-device Copyright (C) 2009 Yan Li <elliot.li.tech@gmail.com>

This script is designed to properly put an USB device into suspend
mode that can then be unplugged safely. It sends a SYNCHRONIZE CACHE
command followed by a START-STOP command (if the device supports it),
unbinds the device from the driver and then suspends the USB
port. After that you can disconnect your USB device safely.

usage:
$0 [options] dev

sample:
$0 /dev/sde

options:
-l show the device and USB bus ID only
-h print this usage

This program comes with ABSOLUTELY NO WARRANTY. This is free
software, and you are welcome to redistribute it under certain
conditions; for details please read the licese at the beginning of the
source code file.
EOF
}

set -e -u

SHOW_DEVICE_ONLY=0
while getopts "l" opt; do
case "$opt" in
h)
usage
exit 2
;;
l)
SHOW_DEVICE_ONLY=1
;;
?)
echo
usage
exit 2
;;
esac
done

DEV_NAME=${!OPTIND:-}


if [ -z ${DEV_NAME} ]; then
usage
exit 2
fi

# mount checking
if mount | grep "^$DEV_NAME[[:digit:]]* "; then
1>&2 echo
1>&2 echo "detected above partition is still mounted, can't suspend device"
1>&2 echo "umount them first"
exit 1
fi

# looking for the parent device with name like
# /devices/pci0000:00/0000:00:1d.7/usb5/5-8

DEVICE=$(udevinfo --query=path --name=${DEV_NAME} --attribute-walk | \
egrep "parent device.*usb[[:digit:]]+/[[:digit:]]+-[[:digit:]]+'" | \
head -n 1 | cut -d"'" -f2)

# the trailing basename of ${DEVICE} is USB_BUS_ID
USB_BUS_ID=${DEVICE##*/}

if [ ${SHOW_DEVICE_ONLY} -eq 1 ]; then
echo Device: ${DEVICE}
echo USB bus ID: ${USB_BUS_ID}
exit 0
fi


if [ -z $DEVICE ]; then
if [ -z $DEVICE ]; then
1>&2 echo "cannot find it's parent USB device, "
1>&2 echo "perhaps it's not an USB device?"
exit 1
fi
fi

# flush all buffers
sync

# root check
if [ `id -u` -ne 0 ]; then
1>&2 echo error, must be run as root, exiting...
exit 1
fi


# send SCSI sync command, some devices don't support this so we just
# ignore errors
sdparm --command=sync "$DEV_NAME" >/dev/null || true
# send SCSI stop command
sdparm --command=stop "$DEV_NAME" >/dev/null

# unbind it
echo -n "${USB_BUS_ID}" > /sys/bus/usb/drivers/usb/unbind

# check if CONFIG_USB_SUSPEND is enabled
POWER_LEVEL_FILE=/sys${DEVICE}/power/level
if [ ! -f "$POWER_LEVEL_FILE" ]; then
1>&2 cat<<EOF
It's safe to remove the USB device now but better can be done. The
power level control file $POWER_LEVEL_FILE
doesn't exist on the system so I have no way to put the USB device
into suspend mode, perhaps you don't have CONFIG_USB_SUSPEND enabled
in your running kernel.

Read
http://elliotli.blogspot.com/2009/01/sa ... linux.html
for an detailed explanation.
EOF
exit 3
fi

echo 'suspend' > "$POWER_LEVEL_FILE"


这个附件的用法是sudo bash usb /dev/sdx(用前要先卸载掉U盘）
这时我目前找到唯一能行的办法。我曾经试过sdparm -command=stop /dev/sdx的方法，但不起作用。
各位如果有更好的方法请无私的贡献出来吧

[wangdu2002]

[wangdu2002]

[feng8899]

其它的USB设备不知道可不可以直接拔出

[eexpress]

只要卸载了，就拔出就是。不管是不是-l 强制卸载与否。

[东风唯笑]

反正。移动硬盘是一定不能热拔插的，数据丢失是很要命的

[hcym]

瞎折腾啥

9.10默认就这功能

[pxw816]

只有XP或者更老的才是这样，删除后灯会灭。但VISTA已经改进了！VISTA删除U盘后和LINUX一样，灯不会灭！

[longdeng]

一直都是直接插拔的！

[minoru_harvest]

这个。。。真不好说呢。
我一个闪盘，在win下，即使弹出后不亮了，还是发热得厉害。我觉得亮不亮没有区别，对于我这个盘。

[swindh]

金剑银剑各有所见啊...
google了一下就到了这个贴子了...
我也不知如何是好啊...继续搜...!

[syrano]

瞎折腾啥

9.10默认就这功能

[大宝]

卸了直接拔，未见小U、小硬有何不良反应~

[hubert_star]

未挂载状态虽然通电，但是硬盘没有读写操作，直接拔下来没问题

想想scsi的热插拔硬盘，通电过程直接拔

[frankvista]

我在gnome-disk-utility,就是"磁盘实用工具",有一个叫做"安全移除"的点一下,USB的LED灯就灭了,不知道调用什么Terminal指令也可以做到?