硬盤快滿了，加硬盤擴容，不管是獨立的服務器，還是云空間新買的硬盤，擴容方式一樣。下面以阿里VPS為例，詳細說一下，掛載硬盤擴容的2種方法。
阿里VPS，個人覺得有以下二個方面需要改進
1，默認不是lvm，所以系統盤/dev/xvda1是不能擴容的，所以如果有大數據的東西，一開始就要考慮到擴容的問題。數據量越大，操作風險越大。
2，不能實現無縫擴容，也就是說，在后臺擴容一下，不用登錄到VPS，進行調整。非專業人士，擴容困難
一，不采用lvm，直接將硬盤掛載到目錄
1，查看硬盤分區情況
[root@iZ94zz3wqciZ ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda1 20641404 14778400 4814480 76% /
tmpfs 509300 0 509300 0% /dev/shm
[root@iZ94zz3wqciZ ~]# fdisk -l
Disk /dev/xvda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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: 0x00078f9c
Device Boot Start End Blocks Id System
/dev/xvda1 * 1 2611 20970496 83 Linux //id是83，非lvm
Disk /dev/xvdb: 23.6 GB, 23622320128 bytes //新買的硬盤
255 heads, 56 sectors/track, 3230 cylinders
Units = cylinders of 14280 * 512 = 7311360 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x27cc1f5a
2，硬盤分區并查看分區情況
[root@iZ94zz3wqciZ ~]# fdisk -S 56 /dev/xvdb //分區
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n //輸入n
Command action
e extended
p primary partition (1-4)
p //主分區
Partition number (1-4): 1 //分區號1
First cylinder (1-3230, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-3230, default 3230):
Using default value 3230
Command (m for help): wq //保存并退出
The partition table has been altered!
[root@iZ94zz3wqciZ ~]# fdisk -l
Disk /dev/xvda: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 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: 0x00078f9c
Device Boot Start End Blocks Id System
/dev/xvda1 * 1 2611 20970496 83 Linux
Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 56 sectors/track, 3230 cylinders
Units = cylinders of 14280 * 512 = 7311360 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x27cc1f5a
Device Boot Start End Blocks Id System
/dev/xvdb1 1 3230 23062172 83 Linux //分區后
3，格式化新分區xvdb1
[root@iZ94zz3wqciZ ~]# mkfs.ext4 /dev/xvdb1 //格式化分區
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1441792 inodes, 5765543 blocks
288277 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
176 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
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 35 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
4，創建目錄，并掛載分區
[root@iZ94zz3wqciZ ~]# mkdir /mnt/fastdfs //掛載目錄
[root@iZ94zz3wqciZ ~]# echo "/dev/xvdb1 /mnt/fastdfs ext4 defaults 0 0" >> /etc/fstab //重啟會自動掛載
[root@iZ94zz3wqciZ ~]# mount -a //掛載所有目錄
[root@iZ94zz3wqciZ ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda1 20641404 14778404 4814476 76% /
tmpfs 509300 0 509300 0% /dev/shm
/dev/xvdb1 22694396 176064 21365516 1% /mnt/fastdfs //新的分區已掛載
到這兒，就把一塊獨立的硬盤加到系統當中了。這種擴容的方式操作簡單，但是擴展性不強，不推薦這種擴容方式。
二，采用lvm的方式，進行硬盤擴容（推薦）
1，取消前面測試的掛載，并刪除分區
[root@iZ94zz3wqciZ ~]# umount -a //取消掛載
[root@iZ94zz3wqciZ ~]# fdisk /dev/xvdb //分區
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): d //刪除分區
Selected partition 1
Command (m for help): wq //保存
The partition table has been altered!
2，安裝lvm
[root@iZ94zz3wqciZ nginx]# uname -a //查看內核信息
Linux iZ94zz3wqciZ 2.6.32-431.23.3.el6.x86_64 #1 SMP Thu Jul 31 17:20:51 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
[root@iZ94zz3wqciZ ~]# yum install lvm2 device-mapper //安裝 LVM2，2.6.9以后版本不用裝device-mapper
[root@iZ94zz3wqciZ nginx]# lsmod | grep dm_mod //是否加載了dm_mod
dm_mod 84337 5 dm_mirror,dm_log
lvm的安裝,首先加載device-mapper模塊，從linux內核2.6.9開始，device-mapper模塊就已經包含在內，所以你只需加載即可。加載mapper模塊：modprobe dm_mod。
3，創建lvm分區
[root@iZ94zz3wqciZ ~]# fdisk /dev/xvdb //分區
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): l
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-2871, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2871, default 2871):
Using default value 2871
Command (m for help): p
Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 63 sectors/track, 2871 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: 0x27cc1f5a
Device Boot Start End Blocks Id System
/dev/xvdb1 1 2871 23061276 83 Linux //不是lvm分區格式
Command (m for help): t //轉換
Selected partition 1
Hex code (type L to list codes): 8e //換成8e
Changed system type of partition 1 to 8e (Linux LVM)
Command (m for help): p
Disk /dev/xvdb: 23.6 GB, 23622320128 bytes
255 heads, 63 sectors/track, 2871 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: 0x27cc1f5a
Device Boot Start End Blocks Id System
/dev/xvdb1 1 2871 23061276 8e Linux LVM //現在lvm分區格式了
Command (m for help): wq
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
4，創建邏輯卷組，以及邏輯卷等
[root@iZ94zz3wqciZ ~]# pvcreate /dev/xvdb1 //創建物理卷
Physical volume "/dev/xvdb1" successfully created
[root@iZ94zz3wqciZ ~]# vgcreate myfiles /dev/xvdb1 //創建邏輯卷組
Volume group "myfiles" successfully created
[root@iZ94zz3wqciZ ~]# vgchange -ay myfiles //激活邏輯卷組
0 logical volume(s) in volume group "myfiles" now active
[root@iZ94zz3wqciZ ~]# vgdisplay myfiles | grep "Total PE" //查看該卷組所有的PE
Total PE 5629
[root@iZ94zz3wqciZ ~]# lvcreate -l 5629 -n fastdfs myfiles //創建邏輯卷
Logical volume "fastdfs" created.
5，格式化邏輯卷
[root@iZ94zz3wqciZ ~]# mkfs.ext4 /dev/myfiles/fastdfs //格式化邏輯卷
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
1441792 inodes, 5764096 blocks
288204 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=4294967296
176 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
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 39 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
6,設置自動掛載，并查看分區
[root@iZ94zz3wqciZ ~]# echo '/dev/myfiles/fastdfs /mnt/fastdfs ext4 defaults 0 0' >> /etc/fstab //自動掛載
[root@iZ94zz3wqciZ ~]# mount -a //手動掛載
[root@iZ94zz3wqciZ ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/xvda1 20641404 14778608 4814272 76% /
tmpfs 509300 0 509300 0% /dev/shm
/dev/mapper/myfiles-fastdfs
22694396 176064 21365516 1% /mnt/fastdfs //lvm邏輯卷已掛載
[root@iZ94zz3wqciZ ~]# reboot //操作完最好重啟一下
7，再擴容一塊硬盤到已有邏輯卷
[root@iZ94zz3wqciZ ~]# fdisk /dev/xvdc //詳細過程同上，就不詳細說明了
[root@iZ94zz3wqciZ ~]# reboot
[root@iZ94zz3wqciZ ~]# pvcreate /dev/xvdc1 //創建物理卷
Physical volume "/dev/xvdc1" successfully created
[root@iZ94zz3wqciZ ~]# vgextend myfiles /dev/xvdc1 //將新硬盤加入卷組
Volume group "myfiles" successfully extended
[root@iZ94zz3wqciZ ~]# vgdisplay myfiles | grep "Total PE" //查看所有PE
Total PE 6907
[root@iZ94zz3wqciZ ~]# lvresize -l 6907 /dev/myfiles/fastdfs //重新規定大小
Size of logical volume myfiles/fastdfs changed from 21.99 GiB (5629 extents) to 26.98 GiB (6907 extents).
Logical volume fastdfs successfully resized
[root@iZ94zz3wqciZ ~]# resize2fs /dev/myfiles/fastdfs //重新規定大小
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/myfiles/fastdfs is mounted on /mnt/fastdfs; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 2
Performing an on-line resize of /dev/myfiles/fastdfs to 7072768 (4k) blocks.
The filesystem on /dev/myfiles/fastdfs is now 7072768 blocks long.
[root@iZ94zz3wqciZ ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/xvda1 20G 15G 4.6G 76% /
tmpfs 498M 0 498M 0% /dev/shm
/dev/mapper/myfiles-fastdfs
27G 172M 26G 1% /mnt/fastdfs //新的5G硬盤加上去了
如果是頻繁的擴容硬盤的話，LVM是首選，擴展真的很方便。
