Linux【6】-硬盘管理2-9-Centos增加磁盘(扩容，LVM)
1：使用背景
废话不多说，磁盘空间不足，增加磁盘，然后扩充现有不足空间磁盘。
本次以Vmware进行测验。
2：我们本次要增加的就是这个
3：我们先添加一个磁盘，20G，添加过程不在赘述
4：添加完成后，要重启一下，要不然系统无法识别
5：添加完成后，我们查看是否添加成功
6：添加成功后，我们开始对分区进行操作
[root@localhost /]# fdisk /dev/sdb
如果上述，出现这种情况
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)
则输入：
partprobe
7：创建物理卷
[root@localhost /]# pvcreate /dev/sdb1
WARNING: dos signature detected on /dev/sda4 at offset 510. Wipe it? [y/n]: y
Wiping dos signature on /dev/sda4.
Physical volume "/dev/sdb1" successfully created.
8：查看新建的物理卷和大小，记住VG name 组名
9：将添加新的物理卷，加载到cl卷组
[root@localhost /]# vgextend cl /dev/sdb1
Volume group "cl" successfully extended
10：再次查看物理卷，也可以使用vgdisplay命令
11：增加磁盘空间
[root@localhost /]# lvresize -L +19.99G /dev/mapper/cl-root #/dev/mapper/cl-root 是磁盘分区的文件系统名 df -h 的时候可以看到
Rounding size to boundary between physical extents: 19.99 GiB.
Size of logical volume cl/root changed from 17.00 GiB (4351 extents) to 36.99 GiB (9469 extents).
Logical volume cl/root su
12：重新识别分区大小
[root@localhost /]# resize2fs /dev/mapper/cl-root
resize2fs 1.42.9 (28-Dec-2013)
resize2fs: Bad magic number in super-block 当尝试打开 /dev/mapper/cl-root 时
找不到有效的文件系统超级块.
13：如果出现“找不到有效的文件系统超级块”错误，用一下命令即可
[root@localhost /]# xfs_growfs /dev/mapper/cl-root
meta-data=/dev/mapper/cl-root isize=512 agcount=4, agsize=1113856 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=4455424, 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 4455424 to 9696256
14：查看磁盘空间是否添加成功
二、讨论
2.1 /dev/mapper/centos-root与/dev/sda的区别
你这是用到了 LVM，
- /dev/sda 是磁盘设备，属于物理卷，使用 pvdisplay 可以查看
- /dev/mapper/centos-root 这是逻辑卷，使用 lvdisplay 可以查看
- 另外可以使用 lsblk 查看磁盘/卷的总览情况
具体示例
[root@pp ~]# fdisk -l
Disk /dev/sda: 483.2 GB, 483183820800 bytes, 943718400 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: 0x00077b25
Device Boot Start End Blocks Id System
/dev/sda1 2048 6143 2048 83 Linux
/dev/sda2 * 6144 2103295 1048576 83 Linux
/dev/sda3 2103296 419430399 208663552 8e Linux LVM
/dev/sda4 419430400 943718399 262144000 83 Linux
Disk /dev/mapper/centos-root: 473.5 GB, 473503367168 bytes, 924811264 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 /dev/mapper/centos-swap: 8594 MB, 8594128896 bytes, 16785408 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
[root@pp ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/centos-root 441G 191G 251G 44% /
devtmpfs 16G 0 16G 0% /dev
tmpfs 16G 0 16G 0% /dev/shm
tmpfs 16G 8.7M 16G 1% /run
tmpfs 16G 0 16G 0% /sys/fs/cgroup
/dev/sda2 1014M 143M 872M 15% /boot
tmpfs 3.2G 0 3.2G 0% /run/user/0
2.2.2.1:/test 24T 22T 2.0T 92% /mnt/nfs
[root@pp ~]# pvdisplay
--- Physical volume ---
PV Name /dev/sda3
VG Name centos
PV Size <199.00 GiB / not usable 0
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 50943
Free PE 0
Allocated PE 50943
PV UUID Gg7VXK-jUJs-OLrB-PcI9-sKoh-RlPp-RN8ZGq
--- Physical volume ---
PV Name /dev/sda4
VG Name centos
PV Size 250.00 GiB / not usable 4.00 MiB
Allocatable yes
PE Size 4.00 MiB
Total PE 63999
Free PE 1
Allocated PE 63998
PV UUID YjtscY-fySg-U6Lc-ITbD-GY70-Q3SF-1pPYkc
[root@pp ~]# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID fckJIw-4zZk-yPce-wiaQ-R70h-Yl3B-TBGsON
LV Write Access read/write
LV Creation host, time localhost, 2018-09-25 16:37:45 +0800
LV Status available
# open 2
LV Size 8.00 GiB
Current LE 2049
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID W3FPGB-61S8-A1ip-YXsa-dwJS-1wfy-NyxgNP
LV Write Access read/write
LV Creation host, time localhost, 2018-09-25 16:37:46 +0800
LV Status available
# open 1
LV Size 440.98 GiB
Current LE 112892
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
[root@pp ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
fd0 2:0 1 4K 0 disk
sda 8:0 0 450G 0 disk
├─sda1 8:1 0 2M 0 part
├─sda2 8:2 0 1G 0 part /boot
├─sda3 8:3 0 199G 0 part
│ ├─centos-root 253:0 0 441G 0 lvm /
│ └─centos-swap 253:1 0 8G 0 lvm [SWAP]
└─sda4 8:4 0 250G 0 part
└─centos-root 253:0 0 441G 0 lvm /
sr0 11:0 1 1024M 0 rom
参考资料
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