LVM logical volume

Logic volume

It is a logical collection of one or more hard disk partitions , It's equivalent to a big hard disk to use . When the hard disk is not enough , You can continue to add new hard disk partitions . You can flexibly use disk partitions

advantage

• Capacity can be increased and reduced at any time
• Multiple hard disks are more cost-effective

technological process

First convert the hard disk into a physical volume pv

Make a volume group vg（ The space of the two hard disks is merged and reorganized by pe As a basic component （ Every pe4M perhaps 4 Multiple ））

Logic volume lv Divide （ Repartition ）pe Integer multiple Increase in excess pe No reduction

command

 Format 
pvcreate
pvcreate  /dev/sdb1  /dev/sdb2

 Volume group path 
/dev/ Volume group name 
 Logical volume path 
/dev/ Volume group name / Logical volume name 

perform

 Ready to have sdb1-6 There are eleven partitions , among 4 Partition No. is an extended partition and is not available 
 Look at the partition format 
[[email protected] ~]# fdisk -l | grep sdb
 disk  /dev/sdb：10.7 GB, 10737418240  byte ,20971520  Sectors 
/dev/sdb1            2048     2099199     1048576   fb  VMware VMFS
/dev/sdb2         2099200     4196351     1048576   fb  VMware VMFS
/dev/sdb3         4196352     6293503     1048576   fb  VMware VMFS
/dev/sdb4         6293504    20971519     7339008    5  Extended
/dev/sdb5         6295552     8392703     1048576   fb  VMware VMFS
/dev/sdb6         8394752    10491903     1048576   fb  VMware VMFS

 Use fidsk, adopt t The command changes all partition types to 8e（Linux lvm）
fdisk /dev/sdb
 Welcome to use  fdisk (util-linux 2.23.2).
 Changes will stay in memory , Until you decide to write changes to disk .
 Think twice before using the write command .
 command ( Input  m  get help )：t
 Zone number  (1-11, Default  11)：1
Hex  Code ( Input  L  List all codes )：8e
 Partition already “VMware VMFS” The type of is changed to “Linux LVM”
 command ( Input  m  get help )：w
The partition table has been altered!
Calling ioctl() to re-read partition table.
 Synchronizing disk .

 Make physical volumes 
[[email protected] ~]# pvcreate /dev/sdb1 /dev/sdb2 /dev/sdb3 /dev/sdb5 /dev/sdb6 
  Physical volume "/dev/sdb1" successfully created.
  Physical volume "/dev/sdb2" successfully created.
  Physical volume "/dev/sdb3" successfully created.
  Physical volume "/dev/sdb5" successfully created.
  Physical volume "/dev/sdb6" successfully created.
 View physical volumes 
[[email protected] ~]# pvscan
  PV /dev/sda2   VG centos          lvm2 [<19.00 GiB / 0    free]
  PV /dev/sdb3                      lvm2 [1.00 GiB]
  PV /dev/sdb2                      lvm2 [1.00 GiB]
  PV /dev/sdb1                      lvm2 [1.00 GiB]
  PV /dev/sdb5                      lvm2 [1.00 GiB]
  PV /dev/sdb6                      lvm2 [1.00 GiB]
  Total: 6 [<24.00 GiB] / in use: 1 [<19.00 GiB] / in no VG: 5 [5.00 GiB]
  
 Delete physical volume 
pvremove /dev/sdb1
Labels on physical volume "/dev/sdb1" successfully wiped
 
 Make volume group 
vgcreate   Volume group name    Disk character   Disk character 
vgcreate vg1 /dev/sdb1 /dev/sdb2 /dev/sdb3 /dev/sdb5 /dev/sdb6
Volume group "vg1" successfully created

 View volume groups    
vgscan
vgdisplay

 Remove the volume group    
vgremove   Volume group name 
vgremove  vg1

 Volume group capacity increase , The partition to be added must first be made into a physical volume 
vgextend   Volume group name    Partition to add      
vgextend jz1 /dev/sdb3
Volume group "jz1" successfully extended

 Volume group shrink 
vgreduce   Volume group name    Partitions to be reduced 
vgreduce jz1 /dev/sdb3
Removed "/dev/sdb3" from volume group "jz1"

 Logical volume management ：
 Partition logic volume  -L pe Capacity size of   -l pe The number of 
lvcreate -L  Capacity size （4M）  -n   Logical volume name    Volume group name 
lvcreate -L 200M -n lv1 jz1
lvcreate -l 20 -n lv2 jz1

 Increase and decrease capacity , Plus sign capacity increase   The minus sign shrinks the volume 
lvextend  -L  + size （+10M）  /dev/ Volume group name / Logical volume name                
          -l  +pe Number        
lvextend -L +100M /dev/jz1/lv1
lvextend -l -10 /dev/mapper/jz1/lv1                          
（ Increased capacity and pe The number of cannot exceed the number of volume groups ）

 Format logical volume 
xfs File system types can only be resized, not resized 
xfs Format does not format data , Formatting is not allowed when mounted 
mkfs -t xfs   Path drive letter 
mkfs -t xfs /dev/jz1/lv1
meta-data=/dev/jz1/lv1           isize=512    agcount=4, agsize=21760 blks
         =                       sectsz=512   attr=2, projid32bit=1
         =                       crc=1        finobt=0, sparse=0
data     =                       bsize=4096   blocks=87040, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0 ftype=1
log      =internal log           bsize=4096   blocks=855, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0

 View the logical volume 
blkid /dev/jz1/lv1
/dev/jz1/lv1: UUID="0ab5594e-1c7f-4314-af82-6af068c4b212" TYPE="xfs"

 mount 
mount /dev/jz1/lv1 /mnt/lv1
 Or use the configuration file to permanently mount 

blkid /dev/jz1/lv1
/dev/jz1/lv1: UUID=“0ab5594e-1c7f-4314-af82-6af068c4b212” TYPE=“xfs”

mount
mount /dev/jz1/lv1 /mnt/lv1
Or use the configuration file to permanently mount