vRanger, SCSI HotAdd, and vSphere Editions

At Quest Data Protection, we’re frequently asked about vRanger utilizing the SCSI HotAdd advanced VDDK transport method in vSphere Essentials, Essentials Plus, Standard, Enterprise, and Enterprise Plus.


Per the VMware VDDK 5.0 Release Notes, SCSI HotAdd is enabled only for vSphere Enterprise and higher:


Licensing. In vSphere 5.0, the SCSI HotAdd feature is enabled only for vSphere editions Enterprise and higher, which have Hot Add licensing enabled. No separate Hot Add license is available for purchase as an add-on. In vSphere 4.1, Hot Add capability was also allowed in Advanced edition. Therefore, customers with vSphere Essentials or Standard edition who use backup products (including VMware Data Recovery) are not able to perform proxy-based backup, which relies on SCSI HotAdd. Those customers must use alternate transport modes.


There’s no change to this in the VDDK 5.0 Update 1 Release Notes.


You don’t take chances with your backups, and neither do we. So we double-checked with VMware on this and confirmed the above.


Why does this matter to you? First, if you’re wondering if the vSphere edition determines whether SCSI HotAdd is available, you have your answer: Yes it does. Second, we hear from end users that other data protection vendors state there’s no correlation to SCSI HotAdd and the vSphere license type – effectively stating that SCSI HotAdd can be utilized in all editions of vSphere. As we’ve seen from VMware above, this is incorrect.


vRanger is VMware ReadyTM certified, which means VMware confirms it properly supports and works with the platform, including supporting the proper APIs and software development kits, including VDDK. So the VDDK inside vRanger includes the advanced transport license check mechanism, as it should. Your data protection processes need to be based on best practices, so make sure your backup solution is properly certified to ensure it uses the latest and greatest VADP and VDDK.


In case you need more detailed information about the history and availability of SCSI HotAdd:


VMware first released the SCSI HotAdd advanced transport mode with VDDK 1.1 (VDDK 1.1 FAQ). The VDDK 1.1 license required paid vSphere platform products. The license enforcement mechanism finally appeared in VDDK 1.2 (VDDK 1.2 Release Notes), when a license check was inserted for advanced transports including SCSI HotAdd.


Note that the VDDK 1.2 Release Notes state specifically that VDDK 1.2 does not support vSphere 5. So if you’re upgrading or deploying new VMFS-5 volumes, make sure your backup product’s going to support vSphere 5, for LAN-free backup and restore.


In their vSphere edition comparison here and here, VMware shows the vSphere Storage API – Data Protection (“VADP”) is available in all editions of vSphere. vRanger utilizes VADP to:


  • Gain block-level access to VMDK files;
  • Perform full, incremental, and differential jobs;
  • Leverage Change Block Tracking (“CBT”);
  • Use Microsoft Volume Shadow Copy Service (“VSS”);
  • And gain access to host internal I/O paths, including SCSI HotAdd


In the same vSphere edition comparison tables, VMware shows HotAdd is only available in Enterprise and Enterprise Plus. Unfortunately in these tables, HotAdd actually refers to CPU and memory, and not the SCSI HotAdd VDDK advanced transport method. But, as we’ve seen above, SCSI HotAdd is also only available in Enterprise and higher.


And that's the way it stands today. In the near future this could change of course, but in the mean time caveat emptor. Don't take chances with your backups. Use vRanger, the safer solution.