一、使用背景
Linux根目录磁盘空间不够用了，当修改了虚拟机模版增加磁盘大小或者插入了一块新硬盘，但是发现系统里的大小还是没改变。
产生的原因是没有给磁盘格式化，没有增加分区。
二、操作方法
1.查看磁盘空间大小，使用df -h 命令，发现挂载根目录节点的/dev/mapper/vg_node003-lv_root 只有7.1G容量。
[root@node-002 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/vg_node003-lv_root 18G 9.3G 7.1G 57% / tmpfs 491M 0 491M 0% /dev/shm /dev/sda1 477M 42M 411M 10% /boot
增加磁盘空间，例如下图使用VM虚拟机增加的方式。
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2.使用fdisk -l命令查看磁盘信息。当看到第一行Disk /dev/sda: 53.7 GB与实际df -h显示内容不符时，说明增加磁盘成功了。
[root@node-002 ~]# fdisk -l Disk /dev/sda: 53.7 GB, 53687091200 bytes 255 heads, 63 sectors/track, 6527 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: 0x00092cf6 Device Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 2611 20458496 8e Linux LVM Disk /dev/mapper/vg_node003-lv_root: 18.8 GB, 18798870528 bytes 255 heads, 63 sectors/track, 2285 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: 0x00000000 Disk /dev/mapper/vg_node003-lv_swap: 2147 MB, 2147483648 bytes 255 heads, 63 sectors/track, 261 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: 0x00000000
3.使用fdisk /dev/sda, 创建新分区。
注意：不同操作系统的磁盘命名方式不同，有些是/dev/vda。具体使用方式参考第三步中fdisk -l首行显示Disk。如笔者在该系统中首行显示为Disk /dev/sda: 53.7 GB, 53687091200 bytes ，故使用命令fdisk /dev/sda）
按照下面Linux操作进行分区。
[root@node-002 ~]# fdisk /dev/sda
命令(输入 m 获取帮助)： m
命令操作
a toggle a bootable flag b edit bsd disklabel c toggle the dos compatibility flag d delete a partition l list known partition types m print this menu n add a new partition o create a new empty DOS partition table p print the partition table q quit without saving changes s create a new empty Sun disklabel t change a partition's system id u change display/entry units v verify the partition table w write table to disk and exit x extra functionality (experts only) 命令(输入 m 获取帮助)： n #new 新分区 Partition type: p primary (2 primary, 1 extended, 1 free) l logical (numbered from 5) Select (default p): p #选择主分区 Selected partition 4 #分区序号 起始 sector (62912512-314572799，默认为 62912512)： #分区开始回车默认 将使用默认值 62912512 Last sector, +扇区 or +size{K,M,G} (62912512-314572799，默认为 314572799)： 将使用默认值 314572799 命令(输入 m 获取帮助)： t #修改分区格式 分区号 (1-5): 4 #修改分区号 Hex code (type L to list codes): 8e #格式选择8e linux LVM Changed system type of partition 4 to 8e (Linux LVM) 命令(输入 m 获取帮助)： p #显示分区信息 Disk /dev/sda: 161.1 GB, 161061273600 bytes 16 heads, 63 sectors/track, 312076 cylinders, total 314572800 sectors Units = 扇区 of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0001a023 设备 启动 起点 终点 块数 Id 系统 /dev/sda1 * 2048 499711 248832 83 Linux /dev/sda2 501758 62912511 31205377 5 扩展 /dev/sda3 499712 501757 1023 83 Linux Partition table entries are not in disk order 命令(输入 m 获取帮助)： w #保存信息 The partition table has been altered! Calling ioctl() to re-read partition table. WARNING: Re-reading the partition table failed with error 16: 设备或资源忙. 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.
重启Linux操作系统，使用reboot命令。
4.创建物理卷，使用pvcreate /dev/sda3命令。
[root@node-002 dev]# pvcreate /dev/sda3 Physical volume "/dev/sda3" successfully created
查看新建的物理卷和大小，使用pvdisplay命令。
[root@node-002 dev]# pvdisplay --- Physical volume --- PV Name /dev/sda2 VG Name centos PV Size <15.00 GiB / not usable 3.00 MiB Allocatable yes (but full) PE Size 4.00 MiB Total PE 3839 Free PE 0 Allocated PE 3839 PV UUID pHtcZN-k0Ne-POHc-CZME-P5yD-N8Vr-DGE9uh "/dev/sda3" is a new physical volume of "84.00 GiB" --- NEW Physical volume --- PV Name /dev/sda3 VG Name PV Size 84.00 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID Jtewe4-172I-WooF-J1Yz-mGon-3pGv-AptNh0
5.将添加新的物理卷，加载到vg_node003卷组，使用vgextend centos /dev/sda3命令。这里的centos 是在上面查明的VG Name
[root@node-002 dev]# vgextend centos /dev/sda3 Volume group "centos" successfully extended
查看卷组信息，使用vgdisplay命令。
[root@node-002 dev]# vgdisplay --- Volume group --- VG Name centos System ID Format lvm2 Metadata Areas 2 Metadata Sequence No 4 VG Access read/write VG Status resizable MAX LV 0 Cur LV 2 Open LV 2 Max PV 0 Cur PV 2 Act PV 2 VG Size 98.99 GiB PE Size 4.00 MiB Total PE 25342 Alloc PE / Size 3839 / <15.00 GiB Free PE / Size 21503 / <84.00 GiB VG UUID RWIfZm-m8Kg-sePL-wHRC-KDso-IRsd-cDlQYX
6.增加 centos 大小，增加84G。使用lvresize -L +84G /dev/mapper/centos-root命令。
注：centos-root在/dev/mapper里面查看 ==这里我在使用过程中路径是/dev/centos/root，/dev/mapper下虽然也有但是用了会提示找不到逻辑卷 这里 用了提示找不到逻辑卷的原因是我是用的是centos，而不是 centos-root
[root@master ~]# lvresize -L +84G /dev/centos/root Insufficient free space: 21504 extents needed, but only 21503 available [root@master ~]# lvresize -L +83.99G /dev/centos/root Rounding size to boundary between physical extents: 83.99 GiB. Size of logical volume centos/root changed from 13.39 GiB (3429 extents) to <97.39 GiB (24931 extents). Logical volume centos/root successfully resized.
7.重新识别centos-root大小，使用resize2fs /dev/mapper/centos-root命令。
[root@node-002 mapper]# resize2fs /dev/mapper/centos-root resize2fs 1.42.9 (28-Dec-2013) resize2fs: Bad magic number in super-block while trying to open /dev/mapper/centos-root Couldn't find valid filesystem superblock.
8.如出现下列情况
resize2fs: Bad magic number in super-block 当尝试打开 /dev/mapper/centos-root 时 找不到有效的文件系统超级块.
9.请使用xfs_growfs /dev/mapper/centos-root
[root@node-002 ~]# xfs_growfs /dev/mapper/centos-root meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=877824 blks = sectsz=512 attr=2, projid32bit=1 = crc=1 finobt=0 spinodes=0 data = bsize=4096 blocks=3511296, 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 3511296 to 25529344
10.查看扩容后的大小 ，使用df -h命令。
[root@node-002 mapper]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 98G 11G 88G 11% / devtmpfs 2.9G 0 2.9G 0% /dev tmpfs 2.9G 0 2.9G 0% /dev/shm tmpfs 2.9G 8.6M 2.9G 1% /run tmpfs 2.9G 0 2.9G 0% /sys/fs/cgroup /dev/sda1 1014M 143M 872M 15% /boot tmpfs 581M 0 581M 0% /run/user/0
11.当看到/dev/mapper/vg_node003-lv_root 已经更新到新的大小时，则表示增加成功。
