pvresize

The pvresize command in Linux is used to resize a physical volume (PV) in the Logical Volume Manager (LVM). This command allows you to increase or decrease the size of an existing physical volume. Typically, this is done when you have extended or reduced the size of the underlying storage device (such as a hard disk or partition), and you want LVM to recognize the changes and adjust the physical volume size accordingly.

Syntax

pvresize [options] <PhysicalVolumePath>

• <PhysicalVolumePath>: The path to the physical volume you want to resize (e.g., /dev/sda1, /dev/vgname/lvname).

Options

• -d, --debug: Enables debugging output.

• -h, --help: Displays help information.

• --setphysicalvolumesize: Specifies the new size for the physical volume.

• -v, --verbose: Shows verbose output.

Example Usage

1. Resize a Physical Volume

If you expand or shrink the underlying disk or partition (e.g., /dev/sda1), you can use pvresize to resize the physical volume to match the new disk size. For example:

sudo pvresize /dev/sda1

This command rescans the /dev/sda1 physical volume and adjusts the size to match any changes that have been made to the underlying disk.

2. Resize a Physical Volume with a Specific Size

You can also manually specify the new size for the physical volume (though this is not common unless you have a very specific requirement). For example, to resize the physical volume /dev/sda1 to 50 GB:

sudo pvresize --setphysicalvolumesize 50G /dev/sda1

This will adjust the size of the physical volume to 50 GB.

3. Resizing After Expanding a Partition

If you have expanded a partition (say using fdisk or parted), you can run pvresize to make the physical volume take up the entire space of the resized partition. For example, after resizing the partition /dev/sda1, you would use:

sudo pvresize /dev/sda1

This will allow LVM to detect the additional space and make it available for use.

Example Output

When you successfully run the pvresize command, you should see output similar to the following:

  Physical volume "/dev/sda1" changed
  1 physical volume(s) resized / 0 physical volume(s) not resized

This indicates that the physical volume /dev/sda1 was resized successfully.

Important Notes

• Resizing Physical Volumes: You cannot shrink a physical volume that is part of an active volume group if there is not enough free space in the volume group. You must ensure that there is enough free space in the volume group before resizing down a physical volume.

• Extending Physical Volumes: Extending a physical volume is more common, especially when adding new disk space to the system. In this case, pvresize will automatically adjust to the new disk size and make additional space available.

• Resizing with Caution: Always ensure that you back up important data before performing operations like resizing, as there can be risks of data loss if something goes wrong.

Conclusion

pvresize is a powerful command for resizing physical volumes in LVM. It's especially useful when your underlying storage device changes size (such as when increasing disk space). This flexibility allows you to manage storage efficiently and scale your systems dynamically.