前言
lvm(Logical Volume Manager) 逻辑卷管理， 可以满足linux系统动态调整各分区大小，满足服务器在不同的运行时期的需求。
以前在Linux下面玩LVM，一般都是选择ext3、ext4格式的文件系统，最近在Ubuntu 16.04.5下安装配置一个MySQL数据库服务器，遂测试了一下XFS文件系统的LVM，其实仔细对比下来，差别不大，只是文件格式化的区别以及件系统的调整命令的不同。下面很多地方不做过多解释，只是简单的记录测试过程。
在测试服务器新增一个磁盘，如下所示，新增的磁盘为/dec/sdc
root@mylnx12:~# fdisk -l
Disk /dev/sdb: 605 GiB, 649613803520 bytes, 1268776960 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: 0x2c2c38b3
Device Boot Start End Sectors Size Id Type
/dev/sdb1 2048 1268774911 1268772864 605G 7 HPFS/NTFS/exFAT
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: 0x6e2369f9
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 62914526 62912479 30G 83 Linux
Disk /dev/sdc: 1023 GiB, 1098437885952 bytes, 2145386496 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: 0x030b81c8
Device Boot Start End Sectors Size Id Type
/dev/sdc1 2048 2145386495 2145384448 1023G 83 Linux
#创建PV
root@mylnx12:~# pvcreate /dev/sdc1
Physical volume "/dev/sdc1" successfully created
root@mylnx12:~# pvscan
PV /dev/sdc1 lvm2 [1023.00 GiB]
Total: 1 [1023.00 GiB] / in use: 0 [0 ] / in no VG: 1 [1023.00 GiB]
#创建VG
root@mylnx12:~# vgcreate -s 32M VolGroup01 /dev/sdc1
Volume group "VolGroup01" successfully created
#新增LV
root@mylnx12:~# lvcreate -L +400G -n LogVol00 VolGroup01
WARNING: xfs signature detected on /dev/VolGroup01/LogVol00 at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/VolGroup01/LogVol00.
Logical volume "LogVol00" created.
root@mylnx12:~# lvscan
ACTIVE '/dev/VolGroup01/LogVol00' [400.00 GiB] inherit
#格式化
root@mylnx12:~# mkfs.xfs /dev/VolGroup01/LogVol00
meta-data=/dev/VolGroup01/LogVol00 isize=512 agcount=4, agsize=26214400 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=0
data = bsize=4096 blocks=104857600, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=51200, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
#挂载点设置
root@mylnx12:~# mkdir /mysql_data
root@mylnx12:~# mount -t xfs /dev/VolGroup01/LogVol00 /mysql_data
root@mylnx12:~# vgdisplay
--- Volume group ---
VG Name VolGroup01
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 2
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 1022.97 GiB
PE Size 32.00 MiB
Total PE 32735
Alloc PE / Size 12800 / 400.00 GiB
Free PE / Size 19935 / 622.97 GiB
VG UUID 8kutIc-bjId-rNWK-UCHo-TU2l-xkwa-idBXCj
#创建另外一个LV
root@mylnx12:~# lvcreate -l 19935 -n LogVol01 VolGroup01
Logical volume "LogVol01" created.
root@mylnx12:~# mkfs.xfs /dev/VolGroup01/LogVol01
meta-data=/dev/VolGroup01/LogVol01 isize=512 agcount=4, agsize=40826880 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=0
data = bsize=4096 blocks=163307520, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=79740, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
root@mylnx12:~# mkdir /mysql_backup
root@mylnx12:~# mount -t xfs /dev/VolGroup01/LogVol01 /mysql_backup/
root@mylnx12:~# df -h
Filesystem Size Used Avail Use% Mounted on
udev 6.9G 0 6.9G 0% /dev
tmpfs 1.4G 8.6M 1.4G 1% /run
/dev/sda1 30G 2.1G 27G 8% /
tmpfs 6.9G 0 6.9G 0% /dev/shm
tmpfs 5.0M 0 5.0M 0% /run/lock
tmpfs 6.9G 0 6.9G 0% /sys/fs/cgroup
/dev/sdb1 596G 70M 566G 1% /mnt
tmpfs 1.4G 0 1.4G 0% /run/user/1000
/dev/mapper/VolGroup01-LogVol00 400G 441M 400G 1% /mysql_data
/dev/mapper/VolGroup01-LogVol01 623G 668M 623G 1% /mysql_backup
修改配置文件/etc/fstab,在其增加下面配置信息，如下所示，以便永久保存，确保下次开机启动不丢失相关挂载点信息。
UUID="a72bd3f8-eb2d-40cb-92c3-d5e32c30d5ff" /mysql_data xfs defaults 0 2
UUID="33325d87-f3f4-4215-abf7-ee795724697e" /mysql_backup xfs defaults 0 2
另外，ext2/ext3/ext4文件系统的调整命令是resize2fs（增大和减小都支持），而XFS文件系统的调整命令是xfs_growfs（只支持增大），当然硬要减小的话，只能在减小后将逻辑分区重新通过mkfs.xfs命令重新格式化才能挂载上，这样的话这个逻辑分区上原来的数据就丢失了。其实没有什么意义。
参考资料：
https://www.jb51.net/article/148553.htm
总结
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