Hot Add Mode Requirements and Troubleshooting

Product version: 11.1

Last Updated: 25 November 2025

Requirements

Hot Add mode can be used only when all of the following conditions are met:

• Transporter must run on a virtual machine only.

• Transporter VM must have access to the datastore where VM disks reside

• VM disks must be attachable. Hot Add is skipped for:

  • RDM/NPIV disks

  • Independent disks

  • VM templates

  • Encrypted VMs processed by unencrypted Transporters

• Transport mode selection must allow Hot Add. Automatically attempted when:

  • Transport mode = Automatic (default)

  • Hot Add only

  • SAN mode unavailable

• If Hot Add is not possible, priority is:

  • SAN

  • Hot Add

  • NBD/NBDSSL

Troubleshooting

Hot Add mode may fail or work inconsistently due to storage access issues or VM configuration limits. When this happens, jobs may fall back to LAN mode or process only some VMs via Hot Add. The sections below outline the most common issues and how to address them.

Hot Add Mode Cannot Be Used

The issue occurs when the Transporter VM cannot attach source VM disks via Hot Add, typically due to data store inaccessibility, unsupported disk types, or inventory mismatches, causing the job to fail or fall back to LAN mode. For more information, see Hot Add Mode Cannot be Used.

Hot Add Works for One VM Only in Multi-VM Jobs

When running backups of multiple VMs using Hot Add mode, issues such as timeouts, disk-attachment delays, or resource contention may cause the mode to behave incorrectly or revert to LAN mode. For more details, see Hot Add Mode Working Incorrectly With Multiple VMs.