- 如果您需要扩展数据盘已有分区，请参考情形一：扩展已有分区。
- 如果新磁盘空间用于增加新分区，请参考情形二：新增并格式化分区。
情形一：扩展已有分区
为了防止数据丢失，不建议扩容已挂载（ mount）的分区和文件系统。请先取消挂载（ umount）分区，完成扩容并正常使用后，重新挂载（ mount）。如果确实需要扩容已挂载（ mount）的分区，则操作如下：
- 实例内核版本 < 3.6：先取消挂载该分区，再修改分区表，最后扩容文件系统。
- 实例内核版本 ≥ 3.6：先修改对应分区表，再通知内核更新分区表，最后扩容文件系统。
如果新磁盘空间用于扩容已有的分区，按照以下步骤在实例中完成扩容：
步骤一：修改分区表
1、运行fdisk -lu /dev/vdb，并记录旧分区的起始和结束的扇区位置。本教程中， /dev/vdb1 的起始扇区位置是 2048，结束扇区位置是 41943039。
> [root@localhost ~]# fdisk -lu /dev/vdb
> Disk /dev/vdb: 42.9 GB, 42949672960 bytes, 83886080 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 label type: dos
> Disk identifier: 0x9277b47b
> Device Boot Start End Blocks Id System
> /dev/vdb1 2048 41943039 20970496 83 Linux
2、使用fdisk命令删除旧分区。
①、运行fdisk -u /dev/vdb：分区数据盘。
②、输入p：打印分区表。
③、输入d：删除分区。
④、输入p：确认分区已删除。
⑤、输入w：保存修改并退出。
> [root@localhost ~]# fdisk -u /dev/vdb
> Welcome to fdisk (util-linux 2.23.2).
> Changes will remain in memory only, until you decide to write them.
> Be careful before using the write command.
> Command (m for help): p
> Disk /dev/vdb: 42.9 GB, 42949672960 bytes, 83886080 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 label type: dos
> Disk identifier: 0x9277b47b
> Device Boot Start End Blocks Id System
> /dev/vdb1 2048 41943039 20970496 83 Linux
> Command (m for help): d
> Selected partition 1
> Partition 1 is deleted
> Command (m for help): p
> Disk /dev/vdb: 42.9 GB, 42949672960 bytes, 83886080 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 label type: dos
> Disk identifier: 0x9277b47b
> Device Boot Start End Blocks Id System
> 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.
3、用fdisk命令新建分区。
①、运行fdisk -u /dev/vdb：分区数据盘。
②、输入p：打印分区表。
③、输入n：新建分区。
④、输入p：选择分区类型为主分区。
⑤、输入<分区号>：选择分区号。本示例选取了1。
> 新分区的起始位置，必须和旧分区的起始位置相同。
> 新分区的结束位置，必须大于旧分区的结束位置，否则会导致扩容失败。
⑥、输入w：保存修改并退出。本教程中，将 /dev/vdb1 由20 GiB扩容到40 GiB。
> [root@localhost ~]# fdisk -u /dev/vdb
> Welcome to fdisk (util-linux 2.23.2).
> Changes will remain in memory only, until you decide to write them.
> Be careful before using the write command.
> Command (m for help): p
> Disk /dev/vdb: 42.9 GB, 42949672960 bytes, 83886080 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 label type: dos
> Disk identifier: 0x9277b47b
> Device Boot Start End Blocks Id System
> Command (m for help): n
> Partition type:
> p primary (0 primary, 0 extended, 4 free)
> e extended
> Select (default p): p
> Partition number (1-4, default 1): 1
> First sector (2048-83886079, default 2048):
> Using default value 2048
> Last sector, +sectors or +size{K,M,G} (2048-83886079, default 83886079):
> Partition 1 of type Linux and of size 30 GiB is set
> Command (m for help): p
> Disk /dev/vdb: 42.9 GB, 42949672960 bytes, 83886080 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 label type: dos
> Disk identifier: 0x9277b47b
> Device Boot Start End Blocks Id System
> /dev/vdb1 2048 62916607 31457280 83 Linux
> Command (m for help): w
> The partition table has been altered!
> Calling ioctl() to re-read partition table.
> Syncing disks.
4、运行lsblk /dev/vdb确保分区表已经增加。
5、运行e2fsck -n /dev/vdb1再次检查文件系统，确认扩容分区后的文件系统状态为clean。
步骤二：通知内核更新分区表
运行partprobe <dst_dev_path>或者partx -u <dst_dev_path>，以通知内核磁盘的分区表已经修改，需要同步更新。
步骤三：扩容文件系统
- ext系列文件系统（例如ext3和ext4）：运行resize2fs /dev/vdb1。
> [root@localhost ~]# resize2fs /dev/vdb1
> resize2fs 1.42.9 (28-Dec-2013)
> Resizing the filesystem on /dev/vdb1 to 7864320 (4k) blocks.
> The filesystem on /dev/vdb1 is now 7864320 blocks long.
- xfs文件系统：先运行mount /dev/vdb1 /mnt/命令，再运行xfs_growfs /dev/vdb1。
> [root@localhost ~]# mount /dev/vdb1 /mnt/
> [root@localhost ~]# xfs_growfs /dev/vdb1
> meta-data=/dev/vdb1 isize=512 agcount=4, agsize=1310720 blks
> = sectsz=512 attr=2, projid32bit=1
> = crc=1 finobt=0 spinodes=0
> data = bsize=4096 blocks=5242880, imaxpct=25
> = sunit=0 swidth=0 blks
> naming =version 2 bsize=4096 ascii-ci=0 ftype=1
> log =internal bsize=4096 blocks=2560, version=2
> = sectsz=512 sunit=0 blks, lazy-count=1
> realtime =none extsz=4096 blocks=0, rtextents=0
> data blocks changed from 5242880 to 7864320
情形二：新增并格式化分区
如果新磁盘空间用于增加新的分区，按照以下步骤在实例中完成扩容：
1、运行fdisk -u /dev/vdb命令新建分区。本教程中，为新增的20GiB新建分区，作为/dev/vdb2 。
> [root@localhost ~]# fdisk -u /dev/vdb
> Welcome to fdisk (util-linux 2.23.2).
> Changes will remain in memory only, until you decide to write them.
> Be careful before using the write commad.
> Command (m for help): p
> Disk /dev/vdb: 42.9 GB, 42949672960 bytes, 83886080 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 label type: dos
> Disk identifier: 0x2b31a2a3
> Device Boot Start End Blocks Id System
> /dev/vdb1 2048 41943039 20970496 83 Linux
> Command (m for help): n
> Partition type:
> p primary (1 primary, 0 extended, 3 free)
> e extended
> Select (default p): p
> Partition number (2-4, default 2): 2
> First sector (41943040-83886079, default 41943040):
> Using default value 41943040
> Last sector, +sectors or +size{K,M,G} (41943040-83886079, default 83886079):
> Using default value 83886079
> Partition 2 of type Linux and of size 20 GiB is set
> Command (m for help): w
> The partition table has been altered!
> Calling ioctl() to re-read partition table.
> Syncing disks.
2、运行命令lsblk /dev/vdb查看分区。
> [root@localhost ~]# lsblk /dev/vdb
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
> vdb 253:16 0 40G 0 disk
> ├─vdb1 253:17 0 20G 0 part
> └─vdb2 253:18 0 20G 0 part
3、格式化新的分区。
- 创建ext4文件系统：mkfs.ext4 /dev/vdb2
> [root@localhost ~]# mkfs.ext4 /dev/vdb2
> mke2fs 1.42.9 (28-Dec-2013)
> Filesystem label=
> OS type: Linux
> Block size=4096 (log=2)
> Fragment size=4096 (log=2)
> Stride=0 blocks, Stripe width=0 blocks
> 1310720 inodes, 5242880 blocks
> 262144 blocks (5.00%) reserved for the super user
> First data block=0
> Maximum filesystem blocks=2153775104
> 160 block groups
> 32768 blocks per group, 32768 fragments per group
> 8192 inodes per group
> Superblock backups stored on blocks:
> 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
> 4096000
> Allocating group tables: done
> Writing inode tables: done
> Creating journal (32768 blocks): done
> Writing superblocks and filesystem accounting information: done
> [root@localhost ~]# blkid /dev/vdb2
> /dev/vdb2: UUID=”e3f336dc-d534-4fdd-af71-b6ff1a55bdbb” TYPE=”ext4″
- 创建ext3文件系统：mkfs.ext3 /dev/vdb2
> [root@localhost ~]# mkfs.ext3 /dev/vdb2
> mke2fs 1.42.9 (28-Dec-2013)
> Filesystem label=
> OS type: Linux
> Block size=4096 (log=2)
> Fragment size=4096 (log=2)
> Stride=0 blocks, Stripe width=0 blocks
> 1310720 inodes, 5242880 blocks
> 262144 blocks (5.00%) reserved for the super user
> First data block=0
> Maximum filesystem blocks=4294967296
> 160 block groups
> 32768 blocks per group, 32768 fragments per group
> 8192 inodes per group
> Superblock backups stored on blocks:
> 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
> 4096000
> Allocating group tables: done
> Writing inode tables: done
> Creating journal (32768 blocks): done
> Writing superblocks and filesystem accounting information: done
> [root@localhost ~]# blkid /dev/vdb2
> /dev/vdb2: UUID=”dd5be97d-a630-4593-9b0f-5056def914ea” SEC_TYPE=”ext2″ TYPE=”ext3″
- 创建xfs文件系统：mkfs.xfs -f /dev/vdb2
> [root@localhost ~]# mkfs.xfs -f /dev/vdb2
> meta-data=/dev/vdb2 isize=512 agcount=4, agsize=1310720 blks
> = sectsz=512 attr=2, projid32bit=1
> = crc=1 finobt=0, sparse=0
> data = bsize=4096 blocks=5242880, imaxpct=25
> = sunit=0 swidth=0 blks
> naming =version 2 bsize=4096 ascii-ci=0 ftype=1
> log =internal log bsize=4096 blocks=2560, version=2
> = sectsz=512 sunit=0 blks, lazy-count=1
> realtime =none extsz=4096 blocks=0, rtextents=0
> [root@localhost ~]# blkid /dev/vdb2
> /dev/vdb2: UUID=”66251477-3ae4-4b44-8b21-5604420dbecb” TYPE=”xfs”
- 创建trfs文件系统：mkfs.btrfs /dev/vdb2
> [root@localhost ~]# mkfs.btrfs /dev/vdb2
> btrfs-progs v4.9.1
> See http://btrfs.wiki.kernel.org for more information.
> Label: (null)
> UUID: 6fb5779b-57d7-4aaf-bf09-82b46f54a429
> Node size: 16384
> Sector size: 4096
> Filesystem size: 20.00GiB
> Block group profiles:
> Data: single 8.00MiB
> Metadata: DUP 1.00GiB
> System: DUP 8.00MiB
> SSD detected: no
> Incompat features: extref, skinny-metadata
> Number of devices: 1
> Devices:
> ID SIZE PATH
> 1 20.00GiB /dev/vdb2
> [root@localhost ~]# blkid /dev/vdb2
> /dev/vdb2: UUID=”6fb5779b-57d7-4aaf-bf09-82b46f54a429″ UUID_SUB=”9bdd889a-ab69-4653-a583-d1b6b8723378″ TYPE=”btrfs”
4、运行mount /dev/vdb2 /mnt挂载文件系统。
5、运行df -h查看目前磁盘空间和使用情况。显示新建文件系统的信息，表示挂载成功，您可以使用新的文件系统。
> [root@localhost ~]# df -h
> Filesystem Size Used Avail Use% Mounted on
> /dev/vda1 40G 1.6G 36G 5% /
> devtmpfs 3.9G 0 3.9G 0% /dev
> tmpfs 3.9G 0 3.9G 0% /dev/shm
> tmpfs 3.9G 460K 3.9G 1% /run
> tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup
> /dev/vdb2 9.8G 37M 9.2G 1% /mnt
> tmpfs 783M 0 783M 0% /run/user/0
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