centos 6.4 扩容

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。
[sss@localhost ~]$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
[sss@localhost ~]$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。
[sss@localhost ~]$ 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
[b]the next reboot or after you run partprobe(8) or kpartx(8)[/b]
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。
[sss@localhost ~]$partprobe
还是出现同样的警告。难道还是不行？
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (Device or resource busy). As a result, it may not reflect all of your changes until after reboot.
管他呢，执行一下格式化吧。
[sss@localhost ~]$sudo mkfs -t ext3 /dev/sda3
居然OK了！这不吓唬人吗？
[sss@localhost ~]$ 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
[sss@localhost ~]$ 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

[sss@localhost ~]$ 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

[sss@localhost ~]$ 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。
[sss@localhost ~]$ 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
[sss@localhost ~]$ sudo vgextend /dev/mapper/vg_vm-lv_root /dev/sda3
Volume group name vg_vm/lv_root has invalid characters
[sss@localhost ~]$ 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？

[sss@localhost ~]$ 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

[sss@localhost ~]$ 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
[sss@localhost ~]$ 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。

[sss@localhost ~]$ 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。
[sss@localhost ~]$ 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.

[sss@localhost ~]$ 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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