步骤
1.备份
就算是无损的扩容，但难免会出什么意外，备份是必不可少的，一般云平台都有备份功能，可直接对磁盘做一次全量备份。
2.用fdisk重新分区
默认的分区如下
root@i-abnawjwo:/# df Filesystem 1K-blocks Used Available Use% Mounted on udev 497752 4 497748 1% /dev tmpfs 101700 440 101260 1% /run /dev/sda1 20509308 1337636 18106816 7% / none 4 0 4 0% /sys/fs/cgroup none 5120 0 5120 0% /run/lock none 508488 0 508488 0% /run/shm none 102400 0 102400 0% /run/user /dev/sdc1 10190136 23032 9626432 1% /data root@i-abnawjwo:/data# cat hello test1
卸载当前的分区 umount /dev/sdc1
若是卸载不掉，有可能是有进程再用，可以用fuser或者lsof查看
fuser -m -v /data fuser -m -v -i -k /data lsof /data
卸载掉后fdisk删除原来的分区，重新分区， 注意开始的磁柱号要和原来的一致（这是保证数据不丢失的关键步骤）
root@i-abnawjwo:/# umount /data
root@i-abnawjwo:/# fdisk /dev/sdc
Command (m for help): d
Selected partition 1
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
Using default value 1
First sector (2048-104857599, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-104857599, default 104857599):
Using default value 104857599
Command (m for help): p
Disk /dev/sdc: 53.7 GB, 53687091200 bytes
64 heads, 32 sectors/track, 51200 cylinders, total 104857600 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x305cddae
Device Boot Start End Blocks Id System
/dev/sdc1 2048 104857599 52427776 83 Linux
Command (m for help): wq
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
重启系统
3.检测分区，扩展分区大小
root@i-abnawjwo:~# e2fsck -f /dev/sdb1 e2fsck 1.42.9 (4-Feb-2014) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/sdb1: 12/655360 files (0.0% non-contiguous), 79664/2621440 blocks root@i-abnawjwo:~# resize2fs -p /dev/sdb1 resize2fs 1.42.9 (4-Feb-2014) Resizing the filesystem on /dev/sdb1 to 13106944 (4k) blocks. The filesystem on /dev/sdb1 is now 13106944 blocks long.
4.重新挂载，查看分区大小，检查数据
root@i-abnawjwo:~# mount /dev/sdb1 /data/ root@i-abnawjwo:/data# cat hello acasdcacsa root@i-abnawjwo:/data# df Filesystem 1K-blocks Used Available Use% Mounted on udev 497752 4 497748 1% /dev tmpfs 101700 428 101272 1% /run /dev/sda1 20509308 1337768 18106684 7% / none 4 0 4 0% /sys/fs/cgroup none 5120 0 5120 0% /run/lock none 508488 0 508488 0% /run/shm none 102400 0 102400 0% /run/user /dev/sdb1 51474044 33100 48803172 1% /data
