Linux 磁盘扩容

一、查看系统磁盘

当使用df -h 命令，可以看到系统的磁盘使用情况，如下所示。

[root@localhost home]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/mapper/VolGroup-lv_root                       51G   24G   25G  49% /tmpfs                 935M     0  935M   0% /dev/shm/dev/xvda1            477M   93M  360M  21% /boot/dev/mapper/VolGroup-lv_home                      199G   60M  189G   1% /home

二、Linux 磁盘扩容

当LVM分区空间不足的时候，可以进行扩容。主要的扩容方法有两种：

1. 通过空余的磁盘进行扩容，这个方法比较简单，不会对原有数据有影响。
2. 将其他LVM分区空间取出一部分给需要扩容的LVM分区。

下面就分别具体介绍这两种方法。

三、利用空余磁盘扩容

1. 首先使用命令fdisk -l 查看磁盘情况，此系统有两块硬盘，/dev/xvda 274.9G，/dev/xvdb 10.7G

[root@localhost home]# fdisk -lDisk /dev/xvda: 274.9 GB, 274877906944 bytes255 heads, 63 sectors/track, 33418 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x000c5cd2    Device Boot      Start         End      Blocks   Id  System/dev/xvda1   *           1          64      512000   83  LinuxPartition 1 does not end on cylinder boundary./dev/xvda2              64       33419   267922432   8e  Linux LVMDisk /dev/xvdb: 10.7 GB, 10737418240 bytes255 heads, 63 sectors/track, 1305 cylindersUnits = cylinders of 16065 * 512 = 8225280 bytesSector size (logical/physical): 512 bytes / 512 bytesI/O size (minimum/optimal): 512 bytes / 512 bytesDisk identifier: 0x00000000

2. 创建pv ,通过pvcreate命令将磁盘/dev/xvdb创建为一个系统PV

[root@localhost home]# pvcreate /dev/xvdb  Physical volume "/dev/xvdb" successfully created

3. 将 PV /dev/xvdb添加到卷组VolGroup 中。磁盘已经添加到VolGroup ，而且卷组的空间增加了10G。使用命令vgextend VolGroup /dev/xvdb

[root@localhost home]# vgextend  VolGroup  /dev/xvdb  Volume group "VolGroup" successfully extended[root@localhost home]# vgs  VG       #PV #LV #SN Attr   VSize   VFree  VolGroup   2   3   0 wz--n- 265.50g    0 

4. 为/ 添加10G的空间。使用命令lvextend -L +10G /dev/mapper/VolGroup-lv_root

[root@localhost home]# lvextend -L +10G  /dev/mapper/VolGroup-lv_root  Size of logical volume VolGroup/lv_root changed from 50.98 GiB (13050 extents) to 55.98 GiB (14330 extents).  Logical volume lv_root successfully resized

5. 逻辑卷扩展后并不会马上生效，需要使用“resize2fs”命令重新加载逻辑卷的大小。使用命令 resize2fs /dev/VolGroup/lv_root。再使用命令df -h查看发现/已经多了10G。

[root@localhost home]# resize2fs /dev/VolGroup/lv_rootresize2fs 1.41.12 (17-May-2010)Filesystem at /dev/VolGroup/lv_root is mounted on /; on-line resizing requiredold desc_blocks = 4, new_desc_blocks = 4Performing an on-line resize of /dev/VolGroup/lv_root to 14673920 (4k) blocks.The filesystem on /dev/VolGroup/lv_root is now 14673920 blocks long.[root@localhost home]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/mapper/VolGroup-lv_root                       60G   24G   34G  41% /tmpfs                 935M     0  935M   0% /dev/shm/dev/xvda1            477M   93M  360M  21% /boot/dev/mapper/VolGroup-lv_home                      199G   60M  189G   1% /home

四、利用其他LVM分区空余空间进行扩容

1. 使用df -h查看每个分区的使用情况。如下，发现/dev/mapper/VolGroup-lv_home容量很充裕，本次扩容通过减少/dev/mapper/VolGroup-lv_home的空间给/dev/mapper/VolGroup-lv_root。

[root@localhost home]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/mapper/VolGroup-lv_root                       60G   24G   34G  41% /tmpfs                 935M     0  935M   0% /dev/shm/dev/xvda1            477M   93M  360M  21% /boot/dev/mapper/VolGroup-lv_home                      199G   60M  189G   1% /home

2. 卸载/home

[root@localhost home]# umount /homeumount: /home: device is busy.        (In some cases useful info about processes that use         the device is found by lsof(8) or fuser(1))

umount /home 如果提示无法卸载，因为有进程占用/home，使用如下命令来终止占用进程：

[root@localhost home]# fuser -m /home  /home:                1463c

如果依然无法卸载，使用以下命令：

[root@localhost home]# umount -l /home

3. 调整/dev/mapper/VolGroup-lv_home分区大小

需要先进行磁盘检测 ，输入命令e2fsck -f /dev/mapper/VolGroup-lv_home。
注意：遇到Abort< y >? 这边输入的是n，才能继续进行。

[root@localhost ~]# e2fsck -f /dev/mapper/VolGroup-lv_homee2fsck 1.41.12 (17-May-2010)The filesystem size (according to the superblock) is 52848640 blocksThe physical size of the device is 52592640 blocksEither the superblock or the partition table is likely to be corrupt!Abort<y>? noPass 1: Checking inodes, blocks, and sizesPass 2: Checking directory structurePass 3: Checking directory connectivityPass 4: Checking reference countsPass 5: Checking group summary information/dev/mapper/VolGroup-lv_home: 26/13213696 files (0.0% non-contiguous), 877250/52848640 blocks

然后输入命令resize2fs -p /dev/mapper/VolGroup-lv_home 100G，进行磁盘重订大小。

[root@localhost ~]# resize2fs -p /dev/mapper/VolGroup-lv_home 100Gresize2fs 1.41.12 (17-May-2010)Resizing the filesystem on /dev/mapper/VolGroup-lv_home to 26214400 (4k) blocks.Begin pass 2 (max = 32768)Relocating blocks             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXBegin pass 3 (max = 1613)Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXThe filesystem on /dev/mapper/VolGroup-lv_home is now 26214400 blocks long.

4. 重新挂载/home

重新挂载后，输入df -h，发现/dev/mapper/VolGroup-lv_home已经改变。

[root@localhost ~]# mount /home[root@localhost ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/mapper/VolGroup-lv_root                       60G   24G   34G  41% /tmpfs                 935M     0  935M   0% /dev/shm/dev/xvda1            477M   93M  360M  21% /boot/dev/mapper/VolGroup-lv_home                       99G   60M   94G   1% /home

5. 设置空闲空间

使用命令vgdisplay，可以看到Free PE/Size 25760 / 100.62 GiB，有了100G的空余空间。

[root@localhost ~]#  lvreduce -L 100G /dev/mapper/VolGroup-lv_home   WARNING: Reducing active and open logical volume to 100.00 GiB  THIS MAY DESTROY YOUR DATA (filesystem etc.)Do you really want to reduce lv_home? [y/n]: y  Size of logical volume VolGroup/lv_home changed from 200.62 GiB (51360 extents) to 100.00 GiB (25600 extents).  Logical volume lv_home successfully resized[root@localhost ~]# vgdisplay  --- Volume group ---  VG Name               VolGroup  System ID               Format                lvm2  Metadata Areas        2  Metadata Sequence No  11  VG Access             read/write  VG Status             resizable  MAX LV                0  Cur LV                3  Open LV               3  Max PV                0  Cur PV                2  Act PV                2  VG Size               265.50 GiB  PE Size               4.00 MiB  Total PE              67969  Alloc PE / Size       42209 / 164.88 GiB  Free  PE / Size       25760 / 100.62 GiB  VG UUID               hQoxGl-H4T9-Lu9W-sITN-hO2B-aos7-T5TmKC

6. 把闲置空间挂在到根目录下

[root@localhost ~]# lvextend -L +100.62G /dev/mapper/VolGroup-lv_root   Rounding size to boundary between physical extents: 100.62 GiB  Size of logical volume VolGroup/lv_root changed from 60.97 GiB (15609 extents) to 161.59 GiB (41368 extents).  Logical volume lv_root successfully resized

使用命令resize2fs -p /dev/mapper/VolGroup-lv_root， 可以不用重启，就显示最新的磁盘空间。

[root@localhost ~]# resize2fs -p /dev/mapper/VolGroup-lv_rootresize2fs 1.41.12 (17-May-2010)Filesystem at /dev/mapper/VolGroup-lv_root is mounted on /; on-line resizing requiredold desc_blocks = 4, new_desc_blocks = 11Performing an on-line resize of /dev/mapper/VolGroup-lv_root to 42360832 (4k) blocks.The filesystem on /dev/mapper/VolGroup-lv_root is now 42360832 blocks long.

7. 最后结果

[root@localhost ~]# df -hFilesystem            Size  Used Avail Use% Mounted on/dev/mapper/VolGroup-lv_root                      159G   24G  128G  16% /tmpfs                 935M     0  935M   0% /dev/shm/dev/xvda1            477M   93M  360M  21% /boot/dev/mapper/VolGroup-lv_home                       99G   60M   94G   1% /home