一. umout 移動硬盤
開始用sftp 將安裝文件copy到服務器的時候，速度太慢了，500k/s。幾個G的東西，copy 這些就要半個多小時，扛不住，拿移動硬盤來copy了。 結果移動硬盤的格式不對。 是NTFS 格式，Linux 識別不了。 只能格式化成FAT32的。 而GG 的win7 系統又不具備格式化成FAT32的功能。 有點小變態。讓同事在XP 下幫我格式化了。
安裝文件copy到服務器後，同事直接將移動硬盤從服務器上拔下來了。 導致的結果是，用df 命令查看，掛載的移動硬盤還存在。
[root@qs-wg-db1 ~]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/sdb3 125G 3.3G 115G 3% /
/dev/sdb1 99M 12M 82M 13% /boot
tmpfs 3.9G 0 3.9G 0% /dev/shm
/dev/sda1 275G 72G 189G 28% /u01
/dev/sdc1 10G 2.0G 8.1G 20% /datatmp
就是這個/dev/sdc1。
這時使用umount 命令，會提示設備忙，無法掛載。
處理方法：
[root@qs-wg-db1 ~]# fuser -km /datatmp
[root@qs-wg-db1 ~]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/sdb3 125G 3.3G 115G 3% /
/dev/sdb1 99M 12M 82M 13% /boot
tmpfs 3.9G 0 3.9G 0% /dev/shm
/dev/sda1 275G 72G 189G 28% /u01
/dev/sdc1 10G 2.0G 8.1G 20% /datatmp
[root@qs-wg-db1 ~]# umount /datatmp
[root@qs-wg-db1 ~]# df -lh
Filesystem Size Used Avail Use% Mounted on
/dev/sdb3 125G 3.3G 115G 3% /
/dev/sdb1 99M 12M 82M 13% /boot
tmpfs 3.9G 0 3.9G 0% /dev/shm
/dev/sda1 275G 72G 189G 28% /u01
成功umount了。
二. umount 光驅
安裝DB 之前，檢查了一下相關包，少了3個。 從系統安裝盤上找了包，安裝了一下。 當時是直接將/dev/cdrom mount 到了/mnt目錄。 也是圖個方便。 結果收工時去拿盤，光驅彈不出來。 同事讓我把cdrom umout掉。 同樣的提示，設備忙。
處理方法：
[root@qs-wg-db1 ~]#fuser –km /dev/cdrom
[root@qs-wg-db1 ~]#eject -- 彈出光驅
在網上搜了一下，正確掛載CD-ROM的方法應該如下：
# mkdir cdrom
# mount /dev/cdrom /mnt/cdrom
或者
# mount /dev/cdrom /media/cdrom
直接掛載在/mnt,/media等系統目錄下，在umount時會出現出錯信息“umount: /mnt/cdrom: device is busy”的情況。
如果一個文件系統處於“busy”狀態的時候，不能卸載該文件系統。如下情況將導致文件系統處於“busy”狀態：
1) 文件系統上面有打開的文件
2) 某個進程的工作目錄在此文件系統上
3) 文件系統上面的緩存文件正在被使用
三. fuser 命令
前面2個umout 都使用了這個fuser 命令。 man了一下這個命令。 內容如下：
[root@qs-wg-db1 ~]# man fuser
FUSER(1) User Commands FUSER(1)
NAME
fuser - identify processes using files or sockets
SYNOPSIS
fuser [-a|-s|-c] [-4|-6] [-n space ] [-k [-i] [-signal ] ] [-muvf] name
fuser -l
fuser -V
DESCRIPTION
fuser displays the PIDs of processes using the specified files or file systems. In the default display mode, each file name is followed by a letter denoting the type
of access:
c current directory.
e executable being run.
f open file. f is omitted in default display mode.
F open file for writing. F is omitted in default display mode.
r root directory.
m mmap'ed file or shared library.
fuser returns a non-zero return code if none of the specified files is accessed or in case of a fatal error. If at least one access has been found, fuser returns zero.
In order to look up processes using TCP and UDP sockets, the corresponding name space has to be selected with the -n option. By default fuser will look in both IPv6 and IPv4 sockets. To change the default, behavior, use the -4 and -6 options. The socket(s) can be specified by the local and remote port, and the remote address. All fields are optional, but commas in front of missing fields must be present:
[lcl_port][,[rmt_host][,[rmt_port]]]
Either symbolic or numeric values can be used for IP addresses and port numbers.
fuser outputs only the PIDs to stdout, everything else is sent to stderr.
OPTIONS
-a Show all files specified on the command line. By default, only files that are accessed by at least one process are shown.
-c Same as -m option, used for POSIX compatibility.
-f Silently ignored, used for POSIX compatibility.
-k Kill processes accessing the file. Unless changed with -signal, SIGKILL is sent. An fuser process never kills itself, but may kill other fuser processes. The effective user ID of the process executing fuser is set to its real user ID before attempting to kill.
-i Ask the user for confirmation before killing a process. This option is silently ignored if -k is not present too.
-l List all known signal names.
-m name specifies a file on a mounted file system or a block device that is mounted. All processes accessing files on that file system are listed. If adirectory file is specified, it is automatically changed to name/. to use any file system that might be mounted on that directory.
-n space Select a different name space. The name spaces file (file names, the default), udp (local UDP ports), and tcp (local TCP ports) are supported. For ports, either the port number or the symbolic name can be specified. If there is no ambiguity, the shortcut notation name/Ispace (e.g. 80/tcp ) can be used.
-s Silent operation. -u and -v are ignored in this mode. -a must not be used with -s.
-signal Use the specified signal instead of SIGKILL when killing processes. Signals can be specified either by name (e.g. -HUP) or by number (e.g. -1). This option is silently ignored if the -k option is not used.
-u Append the user name of the process owner to each PID.
-v Verbose mode. Processes are shown in a ps-like style. The fields PID, USER and COMMAND are similar to ps. ACCESS shows how the process accesses the file. If the access is by the kernel (e.g. in the case of a mount point, awap file, etc.), kernel is shown instead of the PID.
-V Display version information.
-4 Search only for IPv4 sockets. This option must not be used with the -6 option and only has an effect with the tcp and udp namespaces.
-6 Search only for IPv6 sockets. This option must not be used with the -4 option and only has an effect with the tcp and udp namespaces.
- Reset all options and set the signal back to SIGKILL.
FILES
/proc location of the proc file system
fuser 命令顯示訪問某個文件的進程的PID. 其中-k 和 -m 參數上面紅色部分有說明。-k 是kill 訪問這個文件的進程。 沒有進程訪問，就可以成功umount了.