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
The contiguous policy requires that new extents are adjacent to existing extents. If there are suf-
ficient free extents to satisfy an allocation request but a normal allocation policy would not use
them, the anywhere allocation policy will, even if that reduces performance by placing two stripes
on the same physical volume. The cling policy places new extents on the same physical
volume as existing extents in the same stripe of the logical volume. These policies can be
changed using the vgchange command.
In general, allocation policies other than normal are required only in special cases where you
need to specify unusual or nonstandard extent allocation.
LVM volume groups and underlying logical volumes are included in the device special file direct-
ory tree in the /dev directory with the following layout:
/dev/vg/lv/
For example, if you create two volume groups myvg1 and myvg2, each with three logical volumes
named lvo1, lvo2, and lvo3, this create six device special files:
/dev/myvg1/lv01
/dev/myvg1/lv02
/dev/myvg1/lv03
/dev/myvg2/lv01
/dev/myvg2/lv02
/dev/myvg2/lv03
The maximum device size with LVM is 8 Exabytes on 64-bit CPUs.
3.2. Adding Physical Volumes to a Volume Group
To add additional physical volumes to an existing volume group, use the vgextend command.
The vgextend command increases a volume group's capacity by adding one or more free phys-
ical volumes.
The following command adds the physical volume /dev/sdf1 to the volume group vg1.
vgextend vg1 /dev/sdf1
3.3. Displaying Volume Groups
There are two commands you can use to display properties of LVM volume groups: vgs and vg-
display.
The vgscan command will also display the volume groups, although its primary purpose is to
scan all the disks for volume groups and rebuild the LVM cache file. For information on the vg-
scan command, see Section 3.4, “Scanning Disks for Volume Groups to Build the Cache File”.
The vgs command provides volume group information in a configurable form, displaying one line
per volume group. The vgs command provides a great deal of format control, and is useful for
scripting. For information on using the vgs command to customize your output, see Section 9,
“Customized Reporting for LVM”.
3.2. Adding Physical Volumes to a Volume Group
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