Extending SWAP space on Proxmox using lvreduce


Managing SWAP memory is a key element in administering Linux operating systems, especially in virtualization environments like Proxmox. SWAP acts as “virtual memory” that can be used when the system’s physical RAM is full. In this article, we will show how to increase SWAP space on a Proxmox server, using the lvresize tool to free up disk space that can then be allocated to SWAP.

Problem Overview

A user wants to increase SWAP space from 8 GB to 16 GB, but encounters the problem of lacking available space in the LVM volume group, which is required to increase SWAP.

Step 1: Checking Available Space

The command vgs displays the volume groups along with their sizes and available space.

Step 2: Reducing the Volume

Suppose there is a root volume of 457.26 GB, which can be reduced to free up an additional 8 GB for SWAP. Before reducing the volume, it is necessary to reduce the file system on this volume.

However, in the case of the XFS file system, reduction must occur offline or from a live CD.

Step 3: Using lvreduce

This command reduces the root volume by 8 GB, which is confirmed by a message about the volume size change.

Step 4: Deactivating SWAP

Before starting changes in SWAP size, SWAP must first be turned off using the above command.

Step 5: Expanding SWAP

The above commands first increase the SWAP space, then format it and reactivate it.

Finally, we verify the active SWAP areas using the above command to ensure everything is configured correctly.

This process shows how you can flexibly manage disk space on Proxmox servers, adjusting the size of SWAP depending on needs. Using lvreduce requires caution, as any operation on partitions and volumes carries the risk of data loss, therefore it is always recommended to make backups before proceeding with changes.