Expanding OpenVMS 9.2-3 System Disk on Proxmox

While playing around in my OpenVMS sandbox (with the ever-watchful Mr. Wiggles napping on the desk), I found myself needing more room to stretch out—digitally speaking. The pre-built OpenVMS 9.2-3 VMDK image I started with was a meager 8GB, which is like trying to live in a broom closet when you know there’s a perfectly good mansion next door. Strangely, VSI’s own installation guide recommends a minimum of 15GB for a system disk—so why ship an 8GB image? I decided to upgrade the system disk to a roomy 40GB, giving myself not only room to meet that recommendation but a bit of breathing space for logs and additional tools. Here’s how I did it on Proxmox 8.3, and spoiler alert: no coffee was spilled in the process.

Prerequisites

• OpenVMS 9.2-3 VM is installed and accessible
• You are familiar with basic Proxmox CLI commands

Stretching OpenVMS on Proxmox: Disk Expansion Made Easy

Expanding an OpenVMS system disk hosted in a Proxmox virtual machine involves a two-part tango: one on the host (Proxmox) and one inside the guest (OpenVMS). This guide walks you through both sides, ensuring you end up with a much roomier system disk without breaking a sweat—or a filesystem.

Host-Side: Expanding the QCOW2 Disk in Proxmox

Important Note: If you’re using the original .vmdk disk image distributed by VSI, you’ll need to convert it to .qcow2 format. .vmdk disks can’t be resized with the standard Proxmox tools. Think of it like trying to stretch a brick—not gonna happen.

To convert, use a command like:

qemu-img convert -f vmdk X86_V923-community.vmdk -O qcow2 vms.qcow2

Then attach the new .qcow2 disk to your Proxmox VM. Be sure to back up everything before converting.

Step 1: Find Your VM and Disk Info

Fire up your Proxmox terminal and run:

qm config 117

Replace 117 with your actual VM ID. Look for a line like:

scsi0: local-lvm:vm-117-disk-0,size=8G

Step 2: Resize That Disk

To give your disk more breathing room:

qm disk resize 117 scsi0 +32G

This adds 32GB to the existing 8GB disk, for a total of 40GB. If your disk started at a different size, adjust the value accordingly. Proxmox handles the resizing cleanly, no reboot required.

Guest-Side: Expanding the OpenVMS Volume

Now that your virtual disk is physically larger, OpenVMS needs to be told it’s okay to use the new space.

Step 1: Verify Disk Size Increase

Log in to your OpenVMS guest and run:

SHOW DEVICE/FULL DKA0:

You’ll see:

• Total blocks (entire disk size)
• Logical Volume Size (how much OpenVMS currently uses)

Step 2: Make OpenVMS Stretch

Tell OpenVMS to use all available blocks:

SET VOLUME/SIZE DKA0:

No arguments needed. OpenVMS does the math for you.

Step 3: Confirm Expansion

Run this again:

SHOW DEVICE/FULL DKA0:

Check that:

• Logical Volume Size now equals Total blocks
• Free Blocks has noticeably increased (more room for logs, cat photos, and backups!)

Final Thoughts

No reboot, no drama. Just more space for whatever your OpenVMS experiments throw at the disk. But remember: always back up before resizing disks, especially your system volume. Because the only thing worse than a corrupted disk is Mr. Wiggles walking across your keyboard mid-operation.

References

• Proxmox VE Documentation
• OpenVMS HELP SET VOLUME command
• VSI’s documentation for OpenVMS 9.2-3

Happy hacking, and may your virtual disks always have room to grow!