Installation guide
Table Of Contents
- LVM Administrator's Guide
- Table of Contents
- Introduction
- Chapter 1. The LVM Logical Volume Manager
- Chapter 2. LVM Components
- Chapter 3. LVM Administration Overview
- Chapter 4. LVM Administration with CLI Commands
- 1. Using CLI Commands
- 2. Physical Volume Administration
- 3. Volume Group Administration
- 3.1. Creating Volume Groups
- 3.2. Adding Physical Volumes to a Volume Group
- 3.3. Displaying Volume Groups
- 3.4. Scanning Disks for Volume Groups to Build the Cache File
- 3.5. Removing Physical Volumes from a Volume Group
- 3.6. Changing the Parameters of a Volume Group
- 3.7. Activating and Deactivating Volume Groups
- 3.8. Removing Volume Groups
- 3.9. Splitting a Volume Group
- 3.10. Combining Volume Groups
- 3.11. Backing Up Volume Group Metadata
- 3.12. Renaming a Volume Group
- 3.13. Moving a Volume Group to Another System
- 3.14. Recreating a Volume Group Directory
- 4. Logical Volume Administration
- 4.1. Creating Logical Volumes
- 4.2. Persistent Device Numbers
- 4.3. Resizing Logical Volumes
- 4.4. Changing the Parameters of a Logical Volume Group
- 4.5. Renaming Logical Volumes
- 4.6. Removing Logical Volumes
- 4.7. Displaying Logical Volumes
- 4.8. Growing Logical Volumes
- 4.9. Extending a Striped Volume
- 4.10. Shrinking Logical Volumes
- 5. Creating Snapshot Volumes
- 6. Controlling LVM Device Scans with Filters
- 7. Online Data Relocation
- 8. Activating Logical Volumes on Individual Nodes in a Cluster
- 9. Customized Reporting for LVM
- Chapter 5. LVM Configuration Examples
- Chapter 6. LVM Troubleshooting
- Chapter 7. LVM Administration with the LVM GUI
- Appendix A. The Device Mapper
- Appendix B. The LVM Configuration Files
- Appendix C. LVM Object Tags
- Appendix D. LVM Volume Group Metadata
- Index
vgreduce command shrinks a volume group's capacity by removing one or more empty physical
volumes. This frees those physical volumes to be used in different volume groups or to be re-
moved from the system.
Before removing a physical volume from a volume group, you can make sure that the physical
volume is not used by any logical volumes by using the pvdisplay command.
# pvdisplay /dev/hda1
-- Physical volume ---
PV Name /dev/hda1
VG Name myvg
PV Size 1.95 GB / NOT usable 4 MB [LVM: 122 KB]
PV# 1
PV Status available
Allocatable yes (but full)
Cur LV 1
PE Size (KByte) 4096
Total PE 499
Free PE 0
Allocated PE 499
PV UUID Sd44tK-9IRw-SrMC-MOkn-76iP-iftz-OVSen7
If the physical volume is still being used you will have to migrate the data to another physical
volume using the pvmove command. Then use the vgreduce command to remove the physical
volume:
The following command removes the physical volume /dev/hda1 from the volume group
my_volume_group.
# vgreduce my_volume_group /dev/hda1
3.6. Changing the Parameters of a Volume Group
There are several volume group parameters that you can change for an existing volume group
with the vgchange command. Primarily, however, this command is used to deactivate and activ-
ate volume groups, as described in Section 3.7, “Activating and Deactivating Volume Groups”,
The following command changes the maximum number of logical volumes of volume group vg00
to 128.
vgchange -l 128 /dev/vg00
For a description of the volume group parameters you can change with the vgchange command,
see the vgchange(8) man page.
3.7. Activating and Deactivating Volume Groups
When you create a volume group it is, by default, activated. This means that the logical volumes
in that group are accessible and subject to change.
There are various circumstances for which you you need to make a volume group inactive and
thus unknown to the kernel. To deactivate or activate a volume group, use the -a (--available)
argument of the vgchange command.
3.6. Changing the Parameters of a Volume Group
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