摘自 ：http://cache.baiducontent.com/c?m=9f65cb4a8c8507ed4fece7631046893b4c4380146d96864968d4e414c4224615172da2fa663f4344959e2d3956b21f0baca36d2c761e26b69fca894adcbe866d72c8713b214bda074f920eafba5153c337e751fede1ff0cdf02592dec5a3af4327b944040a9781894d731fdd1efa034795b19939550807bb9d2765894e7659df7413e01ca5b5256e76c7ac8a4b4cb268832157cce96eed6205b562e24c4b7a13b74cc05c027d6eb71930ff35785fd4b14ae75b2e0063eb08a4b9b0b5ef5f8dacfd30ebedcbde79c224bd94&p=863fc64ad49c0eb419bd9b7e0e159d&newp=c33ec64ad4db11a058ee97264f4a85231610db2151d4da1067&user=baidu&fm=sc&query=centos+%D0%E9%C4%E2%BB%FA%C0%A9%C8%DD+Re%2Dreading+the+partition+table+failed+with+error+16%3A+Device+or+resource+busy%2E&qid=a5323d5b000035f6&p1=1
遇到的情况是一模一样的，留着自己看看吧！
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背景：开发服务器是虚拟机，原来只规划了2G，后来发现硬盘不够用了，需要进行扩容。
参考文章：《实战Linux下VMware虚拟机根目录空间扩充》
http://blog.sina.com.cn/s/blog_709919050100wap1.html
注：请首先阅读参考文章，本文是在其基础之上，在不同环境中进行的案例。
同时，原文有几处地方没有交代的那么清楚，初学者可能会走弯路，在这里进行了相应补充。
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看到文章说必须基于LVM，那是不是呢？命令检验一下。据说centos默认安装也是LVM的。
[[email protected] ~]$lvdisplay
--- Logical volume ---
LV Path /dev/vg_vm/lv_root
LV Name lv_root
VG Name vg_vm
LV UUID bWyLlY-hYra-7hPc-2eU9-tXMH-FJFa-7ZLDoF
LV Write Access read/write
LV Creation host, time vm.sss, 2015-01-05 03:29:55 +0800
LV Status available
# open 1
LV Size 6.71 GiB
Current LE 1718
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
--- Logical volume ---
LV Path /dev/vg_vm/lv_swap
LV Name lv_swap
VG Name vg_vm
LV UUID oLj3cQ-USD7-JIGZ-HMJz-NlmA-aQf6-lECYyC
LV Write Access read/write
LV Creation host, time vm.sss, 2015-01-05 03:29:56 +0800
LV Status available
# open 1
LV Size 816.00 MiB
Current LE 204
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
[[email protected] ~]$sudo fdisk -l
Disk /dev/sda: 32.2 GB, 32212254720 bytes
255 heads, 63 sectors/track, 3916 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00036057
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 1045 7875584 8e Linux LVM
Disk /dev/mapper/vg_vm-lv_root: 7205 MB, 7205814272 bytes
255 heads, 63 sectors/track, 876 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Disk /dev/mapper/vg_vm-lv_swap: 855 MB, 855638016 bytes
255 heads, 63 sectors/track, 104 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
然后，在windows虚拟机管理软件上，给虚拟机扩容——前提是关闭虚拟机OS。
来个30G，当然，进去之后，可以看到总容量增加了。到32G了，还是没有发现新的分区，虚拟机软件也已经提醒了。
[[email protected] ~]$ sudo fdisk /dev/sda
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 or after you run partprobe(8) or kpartx(8)
Syncing disks.
最后一步出现这样的提示。
但是我们发现，fdisk -l，这个分区已经出来了。
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 1045 7875584 8e Linux LVM
/dev/sda3 1045 3916 23066662 83 Linux
当然，这时候用ls /dev是看不到sd3的。因为还没格式化。
sudo mkfs -t ext3 /dev/sda3 现在也是报错的。
Could not stat /dev/sdb3之类的。
既然上次已经提示了要reboot，那就roboot一下吧。
[[email protected] ~]$partprobe
还是出现同样的警告。难道还是不行？
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (Device or resource busy). As a result, it may not reflect all of your changes until after reboot.
管他呢，执行一下格式化吧。
[[email protected] ~]$sudo mkfs -t ext3 /dev/sda3
居然OK了！这不吓唬人吗？
[[email protected] ~]$ ll /dev/sda3
brw-rw----. 1 root disk 8, 3 Jan 6 10:33 /dev/sda3
嘿嘿，已经有了哦
然而，看看磁盘空间呢？怎么还是这几个分区呢
[[email protected] ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_vm-lv_root 6.7G 6.5G 83M 99% /
tmpfs 495M 80K 495M 1% /dev/shm
/dev/sda1 485M 326M 134M 71% /boot
sudo fdisk -l也可以发现，还是只有一个LVM的分区。
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 1045 7875584 8e Linux LVM
/dev/sda3 1045 3916 23066662 83 Linux
[[email protected] ~]$ sudo lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
lv_root vg_vm -wi-ao---- 6.71g
lv_swap vg_vm -wi-ao---- 816.00m
[[email protected] ~]$ sudo pvcreate /dev/sda3
dev_is_mpath: failed to get device for 8:3
Physical volume "/dev/sda3" successfully created
这里有一个failed，以为出问题了呢，结果下面又success，玩我呢？不管他了。因为一查，都是这样的提示，没有问题。
/dev/mapper/vg_vm-lv_root 6.7G 6.5G 83M 99% /
tmpfs 495M 80K 495M 1% /dev/shm
/dev/sda1 485M 326M 134M 71% /boot
/dev/mapper/vg_vm-lv_root这个应该就是LVM的组名，这里显示的不是sda2.
来扩充这个组吧。
[[email protected] ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_vm-lv_root 6.7G 6.5G 83M 99% /
tmpfs 495M 80K 495M 1% /dev/shm
/dev/sda1 485M 326M 134M 71% /boot
[[email protected] ~]$ sudo vgextend /dev/mapper/vg_vm-lv_root /dev/sda3
Volume group name vg_vm/lv_root has invalid characters
[[email protected] ~]$ sudo vgextend /dev/mapper/vg_vm /dev/sda3
Volume group "vg_vm" successfully extended
原来这个组名，是-之前的字符串——这要是没有文章看着对比分析，谁知道啊？
[[email protected] ~]$ sudo vgdisplay
--- Volume group ---
VG Name vg_vm
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 4
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 2
Act PV 2
VG Size 29.50 GiB
PE Size 4.00 MiB
Total PE 7553
Alloc PE / Size 1922 / 7.51 GiB
Free PE / Size 5631 / 22.00 GiB
VG UUID 8GwL0o-DTdc-Lmkc-gCCC-RBvv-yOQp-wMgpeq
[[email protected] ~]$ sudo lvextend -L +22G /dev/vg_vm/lv_root /dev/sda3
Extending logical volume lv_root to 28.71 GiB
Insufficient free space: 5632 extents needed, but only 5631 available
估计是这其中用了一部分。22G没那么准了。那么就21.0G吧
[[email protected] ~]$ sudo lvextend -L +21.9G /dev/vg_vm/lv_root /dev/sda3
Rounding size to boundary between physical extents: 21.90 GiB
Extending logical volume lv_root to 28.61 GiB
Logical volume lv_root successfully resized
文中所说的vim /etc/fstab这一个步骤，没太看明白。
里面的内容是否有改变？因为看到少了一个mapper
我没有管他，并没有对这个文件进行修改，然后继续往下。
[[email protected] ~]$ sudo e2fsck -f /dev/vg_vm/lv_root
e2fsck 1.41.12 (17-May-2010)
/dev/vg_vm/lv_root is mounted.
e2fsck: Cannot continue, aborting.
不知为何报错。但是这只是一个检查命令，继续往前吧。
[[email protected] ~]$ sudo resize2fs /dev/vg_vm/lv_root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg_vm/lv_root is mounted on /; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/vg_vm/lv_root to 7500800 (4k) blocks.
The filesystem on /dev/vg_vm/lv_root is now 7500800 blocks long.
[[email protected] ~]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_vm-lv_root 29G 6.5G 22G 24% /
tmpfs 495M 80K 495M 1% /dev/shm
/dev/sda1 485M 326M 134M 71% /boot
可以看到，这个逻辑卷已经成功的扩容，根目录又可以装更多东西了。yeah！
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