Linux device names or disk sizes appear changed after HCX RAV migration

Products

• VMware HCX

Issue/Introduction

After performing an HCX Replication Assisted vMotion (RAV) migration of Linux virtual machines, post-migration checks may show that disk device names (e.g., /dev/sda, /dev/sdb) have changed or that disk sizes associated with specific device nodes appear different than the source environment.

Symptoms include:

• A disk identified as /dev/sdf with 20GB now showing as 500GB.

• Disks appearing to have swapped order in the output of df -h or lsblk.

• Potential mount failures if scripts rely on hardcoded /dev/sdX paths.

Environment

VMware HCX

Cause

Linux /dev/sdX device names are non-persistent identifiers assigned by the kernel based on discovery order during boot, which can change when a VM is recreated on a destination host.

Resolution

 

1. Log in to the migrated Linux VM.

2. Run the following command to view the relationship between device names, sizes, and serial numbers: lsblk -o NAME,SIZE,SERIAL,MOUNTPOINT

3. Verify that the total number of disks and their individual sizes match the source VM configuration.

4. Run blkid to identify the UUIDs for all partitions.

5. Check the /etc/fstab file to ensure partitions are mounted using UUID or LABEL instead of device names: cat /etc/fstab

6. If scripts or applications use /dev/sdX paths, update them to use persistent paths found under /dev/disk/by-id/ or /dev/disk/by-uuid/.