Llinux系统增新磁盘实现在线扩容，增加lvm分区容量
本次在虚拟机上模拟新增硬盘，扩容lvm分区系统。
1、虚拟机加盘
给虚拟机加一块30GB的硬盘
2、不重启系统识别新增磁盘
此次在不重启操作系统的情况下，扫描识别新加的磁盘，在实际生产当中发现有时候并没有效果，需要重启服务器才能识别到新加的磁盘。
1、fdisk -l查看当前磁盘信息
[root@localhost ~]# fdisk -l
Disk /dev/sda: 30 GiB, 32212254720 bytes, 62914560 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
Disklabel type: dos
Disk identifier: 0x9edfc7bb
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 1050623 1048576 512M 83 Linux
/dev/sda2 1050624 30427135 29376512 14G 8e Linux LVM
/dev/sda3 30427136 47204351 16777216 8G 82 Linux swap / Solaris
/dev/sda4 47204352 62914559 15710208 7.5G 8e Linux LVM
Disk /dev/mapper/rhel-root: 17 GiB, 18253611008 bytes, 35651584 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/rhel-var: 2 GiB, 2147483648 bytes, 4194304 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/rhel-home: 2 GiB, 2147483648 bytes, 4194304 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
2、扫描磁盘，/sys/class/scsi_host下面有几个host就刷几次，我这边查到有33个host，全部刷新一遍
[root@localhost]# cd /sys/class/scsi_host
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host0/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host1/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host2/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host3/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host4/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host5/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host6/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host7/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host8/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host9/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host10/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host11/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host12/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host13/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host14/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host15/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host16/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host17/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host18/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host19/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host20/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host21/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host22/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host23/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host24/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host25/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host26/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host27/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host28/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host29/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host30/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host31/scan
[root@localhost scsi_host]# echo "- - -" > /sys/class/scsi_host/host32/scan
3、重新执行fdisk -l查看磁盘信息,可以看到多了一个30GB的/dev/sdb盘
[root@localhost ~]# fdisk -l
Disk /dev/sda: 30 GiB, 32212254720 bytes, 62914560 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
Disklabel type: dos
Disk identifier: 0x9edfc7bb
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 1050623 1048576 512M 83 Linux
/dev/sda2 1050624 30427135 29376512 14G 8e Linux LVM
/dev/sda3 30427136 47204351 16777216 8G 82 Linux swap / Solaris
/dev/sda4 47204352 62914559 15710208 7.5G 8e Linux LVM
Disk /dev/mapper/rhel-root: 17 GiB, 18253611008 bytes, 35651584 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/rhel-var: 2 GiB, 2147483648 bytes, 4194304 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/rhel-home: 2 GiB, 2147483648 bytes, 4194304 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/sdb: 30 GiB, 32212254720 bytes, 62914560 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
3、LVM分区扩容
1、查看当前的vg信息，剩余容量等。
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name rhel
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 6
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 21.49 GiB
PE Size 4.00 MiB
Total PE 5502
Alloc PE / Size 5376 / 21.00 GiB
Free PE / Size 126 / 504.00 MiB
VG UUID CWSc1N-T9PW-oPT9-YB9y-Rhsz-xNxV-uP8HoM
[root@localhost ~]# pvscan
PV /dev/sda2 VG rhel lvm2 [14.00 GiB / 0 free]
PV /dev/sda4 VG rhel lvm2 [<7.49 GiB / 504.00 MiB free]
Total: 2 [21.49 GiB] / in use: 2 [21.49 GiB] / in no VG: 0 [0 ]
2、创建pv，将整个硬盘创建一个pv。
[root@localhost ~]# pvcreate /dev/sdb
Physical volume "/dev/sdb" successfully created.
[root@localhost ~]# pvscan
PV /dev/sda2 VG rhel lvm2 [14.00 GiB / 0 free]
PV /dev/sda4 VG rhel lvm2 [<7.49 GiB / 504.00 MiB free]
PV /dev/sdb lvm2 [30.00 GiB]
Total: 3 [51.49 GiB] / in use: 2 [21.49 GiB] / in no VG: 1 [30.00 GiB]
3、扩容vg，可以看到多了30G剩于空间
[root@localhost ~]# vgextend rhel /dev/sdb
Volume group "rhel" successfully extended
[root@localhost ~]# vgdisplay
--- Volume group ---
VG Name rhel
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 3
Act PV 3
VG Size <51.49 GiB
PE Size 4.00 MiB
Total PE 13181
Alloc PE / Size 5376 / 21.00 GiB
Free PE / Size 7805 / <30.49 GiB
VG UUID CWSc1N-T9PW-oPT9-YB9y-Rhsz-xNxV-uP8HoM
4、扩容lv分区，这里选择对/分区进行扩容 。先查看/分区对应的lv name是/dev/rhel/root，当前大小为17G。执行lvextend加了20G空间。
[root@localhost scsi_host]# df -h
Filesystem Size Used Avail Use% Mounted on
devtmpfs 894M 0 894M 0% /dev
tmpfs 909M 0 909M 0% /dev/shm
tmpfs 909M 18M 892M 2% /run
tmpfs 909M 0 909M 0% /sys/fs/cgroup
/dev/mapper/rhel-root 17G 8.2G 8.9G 48% /
/dev/mapper/rhel-var 2.0G 238M 1.8G 12% /var
/dev/mapper/rhel-home 2.0G 47M 2.0G 3% /home
/dev/sda1 507M 159M 348M 32% /boot
tmpfs 182M 28K 182M 1% /run/user/42
tmpfs 182M 4.0K 182M 1% /run/user/0
[root@localhost ~]# vgdisplay -v rhel
--- Volume group ---
VG Name rhel
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 3
Act PV 3
VG Size <51.49 GiB
PE Size 4.00 MiB
Total PE 13181
Alloc PE / Size 5376 / 21.00 GiB
Free PE / Size 7805 / <30.49 GiB
VG UUID CWSc1N-T9PW-oPT9-YB9y-Rhsz-xNxV-uP8HoM
--- Logical volume ---
LV Path /dev/rhel/root
LV Name root
VG Name rhel
LV UUID duRq2B-ki6Q-IoIE-m4ET-VVn1-ZHVx-NrpzPL
LV Write Access read/write
LV Creation host, time localhost, 2019-11-29 12:30:27 -0500
LV Status available
# open 1
LV Size 17.00 GiB
Current LE 4352
Segments 3
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Logical volume ---
LV Path /dev/rhel/var
LV Name var
VG Name rhel
LV UUID ksUp9S-Zta4-EQLr-0m5g-xdqz-lOWu-qAY0Uk
LV Write Access read/write
LV Creation host, time localhost, 2019-11-29 12:30:27 -0500
LV Status available
# open 1
LV Size 2.00 GiB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/rhel/home
LV Name home
VG Name rhel
LV UUID URbY36-FZa0-p5Li-8jgA-sdA4-YlH1-MdUyKs
LV Write Access read/write
LV Creation host, time localhost, 2019-11-29 12:30:27 -0500
LV Status available
# open 1
LV Size 2.00 GiB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Physical volumes ---
PV Name /dev/sda2
PV UUID mBZDl1-eqme-P0tU-amqc-Dmkj-Z6j0-SNvTi3
PV Status allocatable
Total PE / Free PE 3585 / 0
PV Name /dev/sda4
PV UUID lvQFY0-W5DR-OzWa-Uwml-O21E-cEIF-RPywK2
PV Status allocatable
Total PE / Free PE 1917 / 126
PV Name /dev/sdb
PV UUID lXQNKD-eYaQ-TwQM-NAdy-mwiC-QVk8-Y3butQ
PV Status allocatable
Total PE / Free PE 7679 / 7679
[root@localhost ~]# lvextend -L +20G /dev/rhel/root
Size of logical volume rhel/root changed from 17.00 GiB (4352 extents) to 37.00 GiB (9472 extents).
Logical volume rhel/root successfully resized.
[root@localhost ~]# vgdisplay -v rhel
--- Volume group ---
VG Name rhel
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 8
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 3
Open LV 3
Max PV 0
Cur PV 3
Act PV 3
VG Size <51.49 GiB
PE Size 4.00 MiB
Total PE 13181
Alloc PE / Size 10496 / 41.00 GiB
Free PE / Size 2685 / <10.49 GiB
VG UUID CWSc1N-T9PW-oPT9-YB9y-Rhsz-xNxV-uP8HoM
--- Logical volume ---
LV Path /dev/rhel/root
LV Name root
VG Name rhel
LV UUID duRq2B-ki6Q-IoIE-m4ET-VVn1-ZHVx-NrpzPL
LV Write Access read/write
LV Creation host, time localhost, 2019-11-29 12:30:27 -0500
LV Status available
# open 1
LV Size 37.00 GiB
Current LE 9472
Segments 4
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:0
--- Logical volume ---
LV Path /dev/rhel/var
LV Name var
VG Name rhel
LV UUID ksUp9S-Zta4-EQLr-0m5g-xdqz-lOWu-qAY0Uk
LV Write Access read/write
LV Creation host, time localhost, 2019-11-29 12:30:27 -0500
LV Status available
# open 1
LV Size 2.00 GiB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:1
--- Logical volume ---
LV Path /dev/rhel/home
LV Name home
VG Name rhel
LV UUID URbY36-FZa0-p5Li-8jgA-sdA4-YlH1-MdUyKs
LV Write Access read/write
LV Creation host, time localhost, 2019-11-29 12:30:27 -0500
LV Status available
# open 1
LV Size 2.00 GiB
Current LE 512
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 8192
Block device 253:2
--- Physical volumes ---
PV Name /dev/sda2
PV UUID mBZDl1-eqme-P0tU-amqc-Dmkj-Z6j0-SNvTi3
PV Status allocatable
Total PE / Free PE 3585 / 0
PV Name /dev/sda4
PV UUID lvQFY0-W5DR-OzWa-Uwml-O21E-cEIF-RPywK2
PV Status allocatable
Total PE / Free PE 1917 / 0
PV Name /dev/sdb
PV UUID lXQNKD-eYaQ-TwQM-NAdy-mwiC-QVk8-Y3butQ
PV Status allocatable
Total PE / Free PE 7679 / 2685
5、扩容文件系统，上述可以看到lv已经扩容成功，但是df查看文件系统还是没有变化，我们需要再进行文件系统的扩容，这里要区分系统类型，如果是ext4以前的系统格式，需要使用resize2fs命令进行扩容文件系统，xfs格式，需要使用xfs_growfs命令进行扩容。
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 894M 0 894M 0% /dev
tmpfs tmpfs 909M 0 909M 0% /dev/shm
tmpfs tmpfs 909M 18M 892M 2% /run
tmpfs tmpfs 909M 0 909M 0% /sys/fs/cgroup
/dev/mapper/rhel-root xfs 17G 8.2G 8.9G 48% /
/dev/mapper/rhel-var xfs 2.0G 238M 1.8G 12% /var
/dev/mapper/rhel-home xfs 2.0G 47M 2.0G 3% /home
/dev/sda1 xfs 507M 159M 348M 32% /boot
tmpfs tmpfs 182M 28K 182M 1% /run/user/42
tmpfs tmpfs 182M 4.0K 182M 1% /run/user/0
[root@localhost scsi_host]# xfs_growfs /dev/rhel/root
xfs_growfs: /dev/rhel/root is not a mounted XFS filesystem
[root@localhost scsi_host]# xfs_growfs /dev/mapper/rhel-root
xfs_growfs: /dev/mapper/rhel-root is not a mounted XFS filesystem
[root@localhost scsi_host]# xfs_growfs /
meta-data=/dev/mapper/rhel-root isize=512 agcount=7, agsize=655360 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1
data = bsize=4096 blocks=4456448, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log 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 4456448 to 9699328
[root@localhost scsi_host]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
devtmpfs devtmpfs 894M 0 894M 0% /dev
tmpfs tmpfs 909M 0 909M 0% /dev/shm
tmpfs tmpfs 909M 18M 892M 2% /run
tmpfs tmpfs 909M 0 909M 0% /sys/fs/cgroup
/dev/mapper/rhel-root xfs 37G 8.3G 29G 23% /
/dev/mapper/rhel-var xfs 2.0G 238M 1.8G 12% /var
/dev/mapper/rhel-home xfs 2.0G 47M 2.0G 3% /home
/dev/sda1 xfs 507M 159M 348M 32% /boot
tmpfs tmpfs 182M 28K 182M 1% /run/user/42
tmpfs tmpfs 182M 4.0K 182M 1% /run/user/0
[root@localhost scsi_host]#
6、可以看到/分区已在线扩容完成，但是在执行的过程中使用LV Path和Filesystem扩容的时候都报错xfs_growfs: is not a mounted XFS ，直接使用挂载点成功，这个没有想明白是什么原因。
备注：xfs文件系统只能在线扩容，不能在线缩小，ext4可以在线扩容也能在线缩小。
