partprobe

不重啟的情況下重讀分區

補充說明

partprobe命令 用于重讀分區表，當出現刪除文件后，出現仍然占用空間。可以partprobe在不重啟的情況下重讀分區。

語法

partprobe(選項)(參數)

選項

-d：不更新內核；
-s：顯示摘要和分區；
-h：顯示幫助信息；
-v：顯示版本信息。

參數

設備：指定需要確認分區表改變的硬盤對應的設備文件。

實例

使用partprobe不重啟系統添加新的磁盤分區，主機自帶硬盤超過300GB，目前只劃分使用了3個主分區，不到70GB，如下：

[root@localhost ~]# df -h 
Filesystem Size Used Avail Use% Mounted on 
/dev/sda1 29G 3.7G  24G 14% / 
/dev/sda2 29G  22G 5.2G 81% /oracle 
tmpfs    2.0G    0 2.0G  0% /dev/shm

[root@localhost ~]# cat /proc/partitions
major minor  #blocks  name

   8     0  311427072 sda
   8     1   30716248 sda1
   8     2   30716280 sda2
   8     3    8193150 sda3
   8    16     976896 sdb
   8    32     976896 sdc

…省略其他

現在需要給系統添加1個100GB的空間存放數據文件，而又不影響現有系統上業務的運行，使用fdisk結合partprobe命令不重啟系統添加一塊新的磁盤分區。操作步驟如下：

第1步添加新的磁盤分區 ：

[root@localhost ~]# fdisk /dev/sda
The number of cylinders for this disk is set to 38770.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of lilo)
2) booting and partitioning software from other OSs
   (e.g., DOS FDISK, OS/2 FDISK)

command (m for help): p

Disk /dev/sda: 318.9 GB, 318901321728 bytes
255 heads, 63 sectors/track, 38770 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   id  System
/dev/sda1   *           1        3824    30716248+  83  Linux
/dev/sda2            3825        7648    30716280   83  Linux
/dev/sda3            7649        8668     8193150   82  Linux swap / Solaris

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Selected partition 4
First cylinder (8669-38770, default 8669):
Using default value 8669
last cylinder or +size or +sizeM or +sizeK (8669-38770, default 38770): +100G   
Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: 

Device or resource busy.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.

第2步使用工具partprobe讓kernel讀取分區信息：

[root@localhost ~]# partprobe

使用fdisk工具只是將分區信息寫到磁盤，如果需要mkfs磁盤分區則需要重啟系統，而使用partprobe則可以使kernel重新讀取分區信息，從而避免重啟系統。

第3步格式化文件系統：

[root@localhost ~]# mkfs.ext3 /dev/sda4
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
12222464 inodes, 24416791 blocks
1220839 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
746 block groups
32768 blocks per group, 32768 fragments per group
16384 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 
　　　　2654208, 4096000, 7962624, 11239424, 20480000, 23887872

Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information:

done

This filesystem will be automatically checked every 26 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@localhost ~]#

第4步 mount新的分區/dev/sda4：

[root@localhost ~]# e2label  /dev/sda4 /data
[root@localhost ~]# mkdir /data
[root@localhost ~]# mount /dev/sda4 /data
[root@localhost ~]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1             29753556   3810844  24406900  14% /
/dev/sda2             29753588  11304616  16913160  41% /oracle
tmpfs                  2023936         0   2023936   0% /dev/shm
/dev/sda4             96132968    192312  91057300   1% /data

使用partprobe可以不用重啟系統即可配合fdisk工具創建新的分區。