Linux----LVM扩容磁盘空间

Linux系统LVM扩容一个分区相对于Windows来说没有那么直观，但是熟悉命令后，扩容起来也是蛮方便的。

扩容场景如下：

 [root@rhel06 ~]# df -Th
 Filesystem            Type     Size  Used Avail Use% Mounted on
 /dev/sda2             ext4     9.9G  2.2G  7.3G  23% /
 tmpfs                 tmpfs    491M     0  491M   0% /dev/shm
 /dev/sda1             ext4     194M   29M  155M  16% /boot
 /dev/sr0              iso9660  3.6G  3.6G     0 100% /mnt
 /dev/mapper/VG001-lv1 ext4     2.0G   67M  1.9G   4% /lv1

现有一个lvm分区lv1容量2G，希望扩容此分区空间

 [root@rhel06 home]# cat /proc/partitions
 major minor  #blocks  name

    8        0   20971520 sda
    8        1     204800 sda1
    8        2   10485760 sda2
    8        3    2097152 sda3
    8        4          1 sda4
    8        5    2103487 sda5
  253        0    2097152 dm-0

查看partitions  获取当前分区情况和磁盘总空间情况。需要计算20971520-204800-10485760-2097152-2103487-1=6080320，约6G的未使用空间。（dm-0是一个lv分区）

当然使用这种手动方式获取未分区空间太过麻烦。可以用这个shell来完成大量的计算

 [root@rhel06 home]# cat sda.sh
 #!/bin/bash
 total=$(grep 'sda$' /proc/partitions |awk '{print $3}');
 used=0
 for i in $(grep 'sda[[:digit:]]\+$' /proc/partitions |awk '{print $3}' |xargs)
 do
 used=$(( used + i ));
 done
 echo $((( total - used ) / 1024 )) "MB"
 [root@rhel06 home]# ./sda.sh
 5937 MB

接下来执行具体的分区步骤：

一、划分一个新分区并格式化

 [root@rhel06 ~]# fdisk /dev/sda

 Command (m for help): p 

 Disk /dev/sda: 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: 0x00029f55

    Device Boot      Start         End      Blocks   Id  System
 /dev/sda1   *           1          26      204800   83  Linux
 Partition 1 does not end on cylinder boundary.
 /dev/sda2              26        1332    10485760   83  Linux
 /dev/sda3            1332        1593     2097152   82  Linux swap / Solaris
 /dev/sda4            1593        2610     8176089    5  Extended
 /dev/sda5            1593        1854     2103487+  8e  Linux LVM

 Command (m for help): n   #新建分区，由于我已新建了四个分区（主分区和逻辑分区），所以这里只能新建扩展分区，并没有出现分区类型选项
 First cylinder (1855-2610, default 1855):      #开始点，直接回车即可
 Using default value 1855
 Last cylinder, +cylinders or +size{K,M,G} (1855-2610, default 2610): +2G    #+2G，划分一个2G的新分区

 Command (m for help): p

 Disk /dev/sda: 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: 0x00029f55

    Device Boot      Start         End      Blocks   Id  System
 /dev/sda1   *           1          26      204800   83  Linux
 Partition 1 does not end on cylinder boundary.
 /dev/sda2              26        1332    10485760   83  Linux
 /dev/sda3            1332        1593     2097152   82  Linux swap / Solaris
 /dev/sda4            1593        2610     8176089    5  Extended
 /dev/sda5            1593        1854     2103487+  8e  Linux LVM
 /dev/sda6            1855        2116     2104483+  83  Linux

 Command (m for help): w   #保存退出

 [root@rhel06 ~]# partprobe   #不要忘了刷新分区表，虚拟机还是需要重启才能刷新。

 [root@rhel06 ~]# mkfs.ext4 /dev/sda6  #格式化

二、转换sda6分区为pv

 [root@rhel06 ~]# pvcreate /dev/sda6    #转换sda6分区
   dev_is_mpath: failed to get device for 8:6
   Physical volume "/dev/sda6" successfully created
 [root@rhel06 ~]# pvdisplay      #查看系统所有pv，这里sda6已成功转换
   --- Physical volume ---
   PV Name               /dev/sda5
   VG Name               VG001
   PV Size               2.01 GiB / not usable 2.19 MiB
   Allocatable           yes
   PE Size               4.00 MiB
   Total PE              513
   Free PE               1
   Allocated PE          512
   PV UUID               dSHFLX-9Lui-0ZDb-6J2g-pp6A-azuX-vg5yGV

   "/dev/sda6" is a new physical volume of "2.01 GiB"
   --- NEW Physical volume ---
   PV Name               /dev/sda6
   VG Name
   PV Size               2.01 GiB
   Allocatable           NO
   PE Size               0
   Total PE              0
   Free PE               0
   Allocated PE          0
   PV UUID               TEGKht-876S-8MMd-vWkX-rjeI-4UqG-JqRsT2

三、添加新pv到vg

 [root@rhel06 ~]# vgdisplay |grep Name    #查看当前vg名称
   VG Name               VG001
 [root@rhel06 ~]# vgextend VG001 /dev/sda6  #添加“sda6”pv到此vg
   Volume group "VG001" successfully extended
 [root@rhel06 ~]# vgdisplay     #查看vg详情，可以看到vg已经扩容到4g
   --- Volume group ---
   VG Name               VG001
   System ID
   Format                lvm2
   Metadata Areas        2
   Metadata Sequence No  3
   VG Access             read/write
   VG Status             resizable
   MAX LV                0
   Cur LV                1
   Open LV               1
   Max PV                0
   Cur PV                2
   Act PV                2
   VG Size               4.01 GiB
   PE Size               4.00 MiB
   Total PE              1026
   Alloc PE / Size       512 / 2.00 GiB
   Free  PE / Size       514 / 2.01 GiB
   VG UUID               qG18Fp-agAP-gaTp-0crS-Ughm-UilM-2ZftQt

四、调整lv1容量

 [root@rhel06 ~]# lvextend -L 4G /dev/VG001/lv1    #调整lv1分区容量为4G，原来是2G
   Extending logical volume lv1 to 4.00 GiB
   Logical volume lv1 successfully resized
 [root@rhel06 ~]# resize2fs /dev/VG001/lv1    #执行重设大小，对当前lv1有效
 resize2fs 1.41.12 (17-May-2010)
 Filesystem at /dev/VG001/lv1 is mounted on /lv1; on-line resizing required
 old desc_blocks = 1, new_desc_blocks = 1
 Performing an on-line resize of /dev/VG001/lv1 to 1048576 (4k) blocks.
 The filesystem on /dev/VG001/lv1 is now 1048576 blocks long.

五、到此设置已完成，df命令查看已扩容到4G

 [root@rhel06 ~]# df -h
 Filesystem             Size  Used Avail Use% Mounted on
 /dev/sda2              9.9G  2.2G  7.3G  23% /
 tmpfs                  491M     0  491M   0% /dev/shm
 /dev/sda1              194M   29M  155M  16% /boot
 /dev/sr0               3.6G  3.6G     0 100% /mnt
 /dev/mapper/VG001-lv1  4.0G   68M  3.7G   2% /lv1

六、新增lv分区

 [root@rhel06 ~]# lvcreate -L 4G -n lv0data lv1 #在lv1逻辑卷新增lv0data分区   -L指定大小   -n指定名称

问题1：执行partprobe刷新分区表时会出现以下报错：

[root@rhel06 ~]# partprobe
Warning: WARNING: the kernel failed to re-read the partition table on /dev/sda (设备或资源忙).  As a result, it may not reflect all of your changes until after reboot.

这个问题貌似只存在于虚拟机上面，物理机上并没有发现这个问题。重启虚拟机即可。

问题2：fdisk可以查看到sda5分区，但是使用mkfs格式化是提示“没有这个文件或目录”，那是分区表没有刷新或者刷新失败，刷新步骤可参考上一个问题。

    Device Boot      Start         End      Blocks   Id  System
 /dev/sda1   *           1          26      204800   83  Linux
 Partition 1 does not end on cylinder boundary.
 /dev/sda2              26        1332    10485760   83  Linux
 /dev/sda3            1332        1593     2097152   82  Linux swap / Solaris
 /dev/sda4            1593        2610     8176089    5  Extended
 /dev/sda5            1593        1854     2103487+  83  Linux
 [root@rhel06 ~]# mkfs.ext4 /dev/sda5
 mke2fs 1.41.12 (17-May-2010)
 无法对 /dev/sda5 进行 stat 调用 --- 没有那个文件或目录