Study Notes for Linux practice engineers 12

LVMLogical Volume Manager

Physical Volume of PV (physical volume)

VG (volume group) volume group

LV (logical volume) logical volume

 

1. fdisk/dev/SDB

Partition sdb1, sdb2, sdb3

Partition type 8e (Linux LVM)

If the system is using SDB, restart the system to re-read the partition table information of the SDB.

2. # pvcreate/dev/SDB [1-3] initialize the physical volume

3. # vgscan scans physical volumes and creates a volume group database

4. # vgcreate vg0/dev/sdb1/dev/sdb2 use sdb1 and sdb2 to create a volume group vg0

# Vgdisplay vg0

5. # lvcreate-N data-l 10 m Create a new name named data from vg0 in vg0, size 10 m Logical volume

6. # format mkfs. ext3/dev/vg0/Data

7. # Mount/dev/vg0/data/mnt

# Lvdisplay/dev/vg0/data view partition of logical volume data

# Lvcreate-n test-L 5 vg0 use-L to specify the number of logical volumes. The default size of logical volumes is 4 MB, that is, 20 mb.

You must format mkfs. ext3 before using the created logical volume.

# Lvscan scan logical volumes to view their activity

 

# Lvextend-L + 20 m /Dev/vg0/data to expand the logical volume 20 m , Umount partition first, and then expand

# E2fsck-F/dev/vg0/Data forcibly check the data logical volume

# Resize2fs/dev/vg0/Data redefinition of partition size

The preceding three steps must be performed in sequence.

 

# View the current physical volume of the system using pvscan

# Vgextend vg0/dev/sdb2 expand the volume group vg0 and add the partition sdb3 to the volume group

# Pvmove/dev/sdb1 remove a physical volume

# Vgreduce vg0/dev/sdb1 Delete sdb1 from the volume group

Pvmove removes data, but sdb1 is still in vg0 and belongs to the volume group area. vgreduce deletes sdb1 from vg0.

When creating a volume group, the default PE size is 4 MB, and the maximum LV size is 256 GB.

# Vgcreate-S 8 m Vg1/dev/sdb1

-S specifies the PE block size

You can change the maximum logical volume capacity allowed by the volume group by changing the PE block size.

 

TIPS:

# Clear screen

# DF-lH shows the current partition mounting STATUS OF THE SYSTEM

 

Create snapshot (back up data)

# Lvcreate-S-l 52 m -N snap/dev/vg0/Data

-S indicates a snapshot.

-L the snapshot size must be greater than or equal to the logical volume data

-N snapshot name

Snapshots can be used without formatting

 

Procedure for deleting a logical volume

1. umount all LV

2. lvremove/dev/vg0/data (viewed through lvscan) If there is a snapshot, remove the snapshot before removing the logical volume.

3. # vgremove vg0

If any errors occur during use, you can view the system logs.

# Tail/var/log/message