Establish, expand, and contract LVM Logical Volumes

Note:

PV: physical volume

VG: volume group (a VG on the physical layer is composed of one or more PVs)

LV: logical volume (a VG on the logical level is composed of one or more LV)

 

The logical volume creation sequence is PV-> VG-> LV

 

The hard disk of the IDE interface is displayed as hda.

The hard disk of the SCSI interface is displayed as sda.

1. Create a logical volume:

For example, if we select hda5 as the logic, we must first confirm that hda5 is in umount state.

# Df-h # Check the mount status of hda5 in the mount status # umount/dev/hda5 # Remove hda5

# Pvcreate/dev/hda5 # create hda5 as a physical volume # pvscan # View all the current physical volumes and confirm that hda5 exists

# Vgcreate VolGroup0/dev/hda5 # Create a volume group VolGroup0 and add hda5 to the volume group # vgscan # View all the current volume groups. Check that VolGroup0 exists.

# Lvcreate-L 5G-nVol01 VolGroup0 # Create a 5G logical volume Vol01, specify the volume group as VolGroup0 # lvremove VolGroup0/Vol01 # Delete the logical volume Vol01 # lvscan # View all the current logical volumes and confirm that there is Vol01

# Mkfs. ext3/dev/VolGroup0/Vol01 # format the new logical volume Vol01 # mkdir/test # Create a directory # mount/dev/VolGroup0/Vol01/test # mount the logical volume Vol01 to test directory

As a result, a logical volume is complete.

 

II. Extend the logical volume:

2.1 VG space is large enough to only expand LV

# Lvextend-L + 2G/dev/VolGroup0/Vol01 # Add 2 GB space to the logical volume Vol01 # resize2fs/dev/VolGroup0/Vol01 # reset the volume of Vol01 # lvscan # you can see the current lv size changes to 7 GB # reboot # restart the machine (do not restart) # df-hl # After restart, the size of/dev/VolGroup0/Vol01 is changed to 7 GB.

2.2 The VG space is insufficient. Expand the VG

The premise of extending the VG is that there is still unallocated space on your hard disk.

# Fdisk/dev/hdan-> e-> 6-> + 5G-> w # Create a 5G extended differentiation zone number of 6 # mkfs. ext3/dev/hda6 # format the new hda6 # fdisk-l # View all the current partitions and you will see hda6.

 

2.3 next we will merge the new hda6 into VG.

# Pvcreate/dev/hda6 # create hda6 as a physical volume # pvscan # View all the current physical volumes and confirm that hda6 exists

# Vgextend VolGroup0/dev/hda6 # Add hda6 to the VolGroup0 volume group # vgs # view the brief information of vgs and find that the space of VolGroup0 increases

III. Zoom outLVLogical Volume(Note:700 MRemaining size after reduction)

Today I learned how to reduce LV size in RHEL6, and the example below is to set LV "/dev/mapper/vg_redhat6-lv_pgdata_01"
To 700 M, that is, to reduce 86 M.

3.1 Current LVM information

/Dev/mapper/vg_redhat6-lv_root 13G 7.7G 4.6G 63%/tmpfs 250 M 264 K 250 M 1%/dev/shm/dev/sda1 485 M 31 M 429 M 7%/boot/ dev/mapper/vg_redhat6-lv_opt 786 M 593 M 154 M 80%/opt

 

3.2 unmount)

[[Email protected] ~] # Umount/dev/mapper/vg_redhat6-lv_opt

 

3.3 check the file system (e2fsck)

[[Email protected] ~] # E2fsck/dev/mapper/vg_redhat6-lv_opt e2fsck 1.41.12 (17-May-2010)/dev/mapper/vg_redhat6-lv_opt: clean, 236/49152 files, 154817/179200 blocks

   

3.4 shrink the file system (resize2fs)

[[Email protected] ~] # Resize2fs-f/dev/mapper/vg_redhat6-lv_opt 700 M resize2fs 1.41.12 (17-May-2010) Resizing the filesystem on/dev/mapper/vg_redhat6-lv_pgdata_01 to 179200 (4 k) blocks. the filesystem on/dev/mapper/vg_redhat6-lv_pgdata_01 is now 179200 blocks long.

3.5 LV reduce)

[[Email protected] ~] # Lvreduce-L 700 M/dev/mapper/vg_redhat6-lv_opt WARNING: rolling Cing active logical volume to 700.00 MiB This may destroy your data (filesystem etc .) Do you really want to reduce lv_pgdata_01? [Y/n]: y Indexing Cing logical volume lv_pgdata_01 to 700.00 MiB Logical volume lv_pgdata_01 successfully resized

3.6 view the current LV size

[[Email protected] ~] # Lvs lv vg Attr LSize Origin Snap % Move Log Copy % Convert lv_opt vg_redhat6-wi-ao ---- 700.00 m lv_root vg_redhat6-wi-ao ---- 13.10g lv_swap vg_redhat6-wi-ao ---- 1.91g

3.7 re-mount the file system. View

[[Email protected] ~] # Mount-t ext4/dev/mapper/vg_redhat6-lv_opt/opt [[Email protected] ~] # Df-hl Filesystem Size Used Avail Use % Mounted on /Dev/mapper/vg_redhat6-lv_root 13G 7.7G 4.6G 63%/ Tmpfs 250 M 264 K 250 M 1%/dev/shm /Dev/sda1 485 M 31 M 429 M 7%/boot /Dev/mapper/vg_redhat6-lv_opt 688 M 593 M 61 M 91%/opt

Note: The Directory/database/skytf/pgdata1 has been successfully reduced to about 700 MB.

        
Ps. At this time, vg has free space. You can use # vgdisplay to view the remaining size (in the red box), and use 2.1 to allocate the idle size to other logical volumes. For example

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--Summary
  
Before reducing the LV size, you must first reduce the file system size.

This article from the "IT-smile" blog, please be sure to keep this http://pynliu.blog.51cto.com/5027391/1573438

Establish, expand, and contract LVM Logical Volumes