pvchange Command in Linux
The pvchange command in Linux changes the attributes of physical volumes (PV). It modifies properties such as availability, allocation, and metadata settings of a physical volume. It modifies physical volume attributes dynamically without requiring reconfiguration or data loss.
Table of Contents
Here is a comprehensive guide to the options available with the pvchange command â
Syntax of pvchange Command
The syntax of the pvchange command in Linux is as follows −
pvchange [options] [physical_volume]
The [options] field in the above syntax is used to specify various flags/options that define what changes are to be applied. The [physical_volume] field is used to specify the specific physical volume being modified.
pvchange Command Options
The options of the Linux pvchange command are listed below −
| Flags | Options | Description |
|---|---|---|
| --addtag Tag | Adds a tag to a PV, VG, or LV. It can be repeated to add multiple tags. | |
| -a | --all | Change all visible PVs. |
| -x y|n | --allocatable y|n | Enable or disable allocation of physical extents on this PV. |
| -A y|n | --autobackup y|n | Enable or disable automatic metadata backup. |
| --commandprofile String | Specify a command profile for configuration. | |
| --config String | Override lvm.conf settings with a custom configuration. | |
| -d | --debug ... | Set debug level (1-6) for detailed logging. |
| --deltag Tag | Deletes a tag from a PV, VG, or LV. It can be repeated. | |
| --devices PV | Specify devices the command can use (comma-separated list). | |
| --devicesfile String | Specify a file listing devices for LVM use. | |
| --driverloaded y|n | Disable device-mapper use (for debugging). | |
| -f | --force | Override checks, confirmations, and protections (use with caution). |
| -h | --help | Display help text. |
| --journal String | Record information in the systemd journal. | |
| --lockopt String | Pass options for lvmlockd. | |
| --longhelp | Display extended help text. | |
| --metadataignore y|n | Ignore metadata areas on the PV (prevents metadata storage). | |
| --nohints | Ignore the hints file when locating PVs. | |
| --nolocking | Disable locking. | |
| --profile String | Alias for --commandprofile or --metadataprofile. | |
| -q | --quiet ... | Suppress output and log messages. |
| --reportformat basic|json | Set output format for reports (basic or JSON). | |
| -S String | --select String | Select objects for processing based on criteria. |
| -t | --test | Run in test mode (no metadata updates). |
| -u | --uuid | Generate a new UUID for the specified PVs. |
| -v | --verbose ... | Set verbosity level (1-4). |
| --version | Display version information. | |
| -y | --yes | Assume yes for all confirmations (use with caution). |
Examples of pvchange Command in Linux
In this section, the usage of the pvchange command in Linux will be explored with examples.
- Enabling Allocation of Physical Extents on a Physical Volume (PV)
- Disabling Allocation of Physical Extents on a Physical Volume (PV)
- Adding a Tag to a Physical Volume (PV)
- Removing a Tag from a Physical Volume (PV)
- Applying Changes on a Physical Volume (PV) by a Specific Criteria
- Running the pvchange Command in Test Mode
- Displaying Usage Help
Enabling Allocation of Physical Extents on a Physical Volume (PV)
To enable the allocation of physical extents on a physical volume (PV), use the pvchange command with the -x or --allocatable option −
sudo pvchange -x y /dev/vda3
Disabling Allocation of Physical Extents on a Physical Volume (PV)
To disable the allocation of physical extents on a physical volume (PV), use the -x or --allocatable option with n −
sudo pvchange -x n /dev/vda3
The above command prevents the allocation of physical extents on the free space of one or more physical volumes.
Adding a Tag to a Physical Volume (PV)
To add a tag to a physical volume (PV), use the --addtag option with the pvchange command −
sudo pvchange --addtag "mypv" /dev/vda3
To verify the tag change, run the following command −
sudo pvs -o pv_tags
Removing a Tag from a Physical Volume (PV)
To remove a tag to a physical volume (PV), use the --deltag option with the pvchange command −
sudo pvchange --deltag "mypv" /dev/vda3
Applying Changes on a Physical Volume (PV) by a Specific Criteria
To apply changes to a physical volume (PV) based on specific criteria, use the -S or --select option. For example, to enable allocation only for physical volumes that are less than 2GB, use the pvchange command in the following way −
sudo pvchange -x y -S 'pv_size < 2G' /dev/vda3
To list all the attributes that can be used as criteria, use the following command −
pvs -o help
Running the pvchange Command in Test Mode
To dry run the pvchange command, use the -t or --test option −
sudo pvchange -t -x n /dev/vda3
Displaying Usage Help
To display usage help of the pvchange command, use the -h or --help option −
pvchange -h
To display the detailed help, use the --longhelp option −
pvchange --longhelp
Conclusion
The pvchange command in Linux modifies the attributes of physical volumes, allowing changes to availability, allocation, and metadata settings without data loss. It provides various options to enable or disable allocation, manage metadata, add or remove tags, and perform test runs. Examples demonstrate practical usage, such as enabling or disabling allocation, tagging physical volumes, and applying changes based on specific criteria. The command also includes options for debugging, configuring profiles, and displaying help information.