Demonstration of the production process of lvm software under linux

The previous article introduced lvm, and today I will demonstrate the process of making lvm. The production process of lvm has the following steps:

1. Disk partition

2. Use partition to make pv

3. Create vg with pv

4. Split lv from vg

5. Format lv and mount it to the directory using

Next, let’s complete the above process.

Partition

First, let’s take a look at the partitioning of the disk.

# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0   40G  0 disk 
├─sda1   8:1    0    2M  0 part 
├─sda2   8:2    0    1G  0 part /boot
├─sda3   8:3    0    1G  0 part [SWAP]
├─sda4   8:4    0   10G  0 part /
└─sda5   8:5    0  100M  0 part 
sdb      8:16   0    1G  0 disk 
sdc      8:32   0    1G  0 disk 
sdd      8:48   0    1G  0 disk 
sde      8:64   0    1G  0 disk

As you can see, there are 5 disks on my host. Except for the sda ​​disk, the other disks have not been partitioned. In addition, the sda ​​disk also has remaining space. Now, partition the other 4 disks as well. Use the fdisk or gdisk tool to partition, and the specific process is omitted here. After partitioning, the information is as follows:

# lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sda      8:0    0   40G  0 disk 
├─sda1   8:1    0    2M  0 part 
├─sda2   8:2    0    1G  0 part /boot
├─sda3   8:3    0    1G  0 part [SWAP]
├─sda4   8:4    0   10G  0 part /
└─sda5   8:5    0  100M  0 part 
sdb      8:16   0    1G  0 disk 
└─sdb1   8:17   0 1023M  0 part 
sdc      8:32   0    1G  0 disk 
└─sdc1   8:33   0 1023M  0 part 
sdd      8:48   0    1G  0 disk 
└─sdd1   8:49   0 1023M  0 part 
sde      8:64   0    1G  0 disk 
└─sde1   8:65   0 1023M  0 part

Making pv

First, we need to install the lvm2 software.

yum install lvm2

There are several related commands about pv:

• pvscan View pv on the system

• pvdisplay List pv Usage

• pvcreate Make pv

• pvremove Delete the pv, even if a partition does not have the pv attribute

Now we use partitions to make pv.

Usage: pvcreate partition...

# pvcreate /dev/sdb1 /dev/sdc1
  Physical volume "/dev/sdb1" successfully created.
  Physical volume "/dev/sdc1" successfully created.
# 这样就制作好了两个pv

The following uses pvscan to view all pvs on the system

# pvscan
  PV /dev/sdc1                      lvm2 [1023.00 MiB]
  PV /dev/sdb1                      lvm2 [1023.00 MiB]
  Total: 2 [<2.00 GiB] / in use: 0 [0   ] / in no VG: 2 [<2.00 GiB]
# 共有2个pv，总大小2G左右，0个pv被使用

View the usage of a certain pv: pvdispaly [partition name]

# pvdisplay /dev/sdb1
  "/dev/sdb1" is a new physical volume of "1023.00 MiB"
  --- NEW Physical volume ---
  PV Name               /dev/sdb1
  VG Name               
  PV Size               1023.00 MiB
  Allocatable           NO
  PE Size               0   
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               6sl1Eg-S6BJ-1QYX-NAFs-9dIB-zEKN-jz7lYM

Then, we will delete these two PVs

# pvremove /dev/sd{b,c}1
  Labels on physical volume "/dev/sdb1" successfully wiped.
  Labels on physical volume "/dev/sdc1" successfully wiped.

Finally, let’s make 3 PVs

# pvcreate /dev/sd{b,c,d}1
  Physical volume "/dev/sdb1" successfully created.
  Physical volume "/dev/sdc1" successfully created.
  Physical volume "/dev/sdd1" successfully created.

Make vg

vg also has several related commands, as follows:

• vgcreate makes vg. This command is the most complex of these commands.

• vgscan Browse vg on the system

• vgremove Delete a vg

• vgdisplay View vg Usage

• vgextend Expand vg, that is, add pv

• vgreduce Remove pv from vg

First look at the command to make vg:

vgcreate [-s N[m|g|t]] vg name pv name

Options and parameters:

• -s is followed by size, m, g, t can be in upper or lower case, and is used to set the pe size. If you omit this parameter, the default size will be used, which is generally 4M

• vg name: Unlike the pv process, you need to customize the name of the vg here,

• PV name, which PVs made vg.

Let’s make vg

# vgcreate vgwww /dev/sd{b,c,d}1   
Volume group "vgwww" successfully created

Browse what vg has

# vgscan   
Reading volume groups from cache.   
Found volume group "vgwww" using metadata type lvm2

Check the relevant information of vg

# vgdisplay 
  --- Volume group ---
  VG Name               vgwww
  System ID             
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                3
  Act PV                3
  VG Size               <2.99 GiB
  PE Size               4.00 MiB
  Total PE              765
  Alloc PE / Size       0 / 0   
  Free  PE / Size       765 / <2.99 GiB
  VG UUID               pd3HIi-NnES-DsdO-d35L-qoJB-OrwI-vkhfqV

Now we have vgwww Perform expansion operations

# vgextend vgwww /dev/sde1
  Volume group "vgwww" successfully extended

Create lv

There are also some related commands for lv, as follows:

• lvcreate: Make lv

• lvscan: Query the lv on the system

• lvdisplay: Display the status of lv

• lvextend: Increase lv capacity

• lvreduce: Reduce lv capacity

• ##lvremove: Delete a lv

• lvresize: Adjust the lv capacity size

Let’s look at the command to make lv

• lvcreate [-L N [m/g/t]] [-n lv name] vg name

• lvcreate [-l N] [-n lv name] vg name

Option parameters:

• -L followed by capacity, set the size of lv

• -l followed by how many PEs to use Quantity

• You don’t need to set the lv name, then the system will automatically set the lv name

# lvcreate -L 1G -n lvwww vgwww
  Logical volume "lvwww" created.
# lvscan
  ACTIVE            '/dev/vgwww/lvwww' [1.00 GiB] inherit

The following will demonstrate how to expand the lv by 1G , to expand the capacity, use the lvresize command. First, make sure that the remaining space of vg is greater than 1G, and then expand it

# vgdisplay vgwww
  --- Volume group ---
  VG Name               vgwww
  System ID             
  Format                lvm2
  Metadata Areas        4
  Metadata Sequence No  5
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                4
  Act PV                4
  VG Size               3.98 GiB
  PE Size               4.00 MiB
  Total PE              1020
  Alloc PE / Size       256 / 1.00 GiB
  Free  PE / Size       764 / 2.98 GiB  <=== 还有剩余3G的空间
  VG UUID               pd3HIi-NnES-DsdO-d35L-qoJB-OrwI-vkhfqV
  
  # lvresize -L +1G /dev/vgwww/lvwww 
  Size of logical volume vgwww/lvwww changed from 1.00 GiB (256 extents) to 2.00 GiB (512 extents).
  Logical volume vgwww/lvwww successfully resized.

Format and mount

/dev/vgwww/lvwww It is equivalent to a partition. If you want to use the partition, you need to format it first, and then mount it using

# mkfs.xfs /dev/vgwww/lvwww
# blkid
……
/dev/mapper/vgwww-lvwww: UUID="fcbff612-a169-4542-ad92-6d53abe7b982" TYPE="xfs" 
# mount /dev/vgwww/lvwww /www
[root@localhost ~]# df -h
……
/dev/mapper/vgwww-lvwww  2.0G   33M  2.0G    2% /www

. At this point, the entire process is over, and the new file system has been created.

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