Virtual Disk Development Kit Release Notes

Release date: 24 MAY 2018 | Build number: VDDK 8535999
VDDK 6.7.0 EP1 fixes | Last document update: 23 AUG 2018
Check frequently for additions and updates to these release notes.


About the Virtual Disk Development Kit

The Virtual Disk Development Kit (VDDK) 6.7.0 EP1 is patch release based on partner demand. It is a possible replacement for VDDK 6.7.

VDDK 6.7.0 EP1 supports the same set of operating systems to perform proxy backup as VDDK 6.7.

Changes and New Features

This release contains bug fixes but no new features.

  • Upgrade OpenSSL to get security fixes
  • Improved performance of HotAdd
  • ESXi direct connect more robust

Compatibility Notices

This VDDK release is backward compatible with vSphere 6.0, vSphere 6.5, vSAN 6.6, vSAN 6.6.1, and vSphere 6.7.

ESXi hosts and especially pre-6.7 vCenter Server should be upgraded in conjunction with VDDK libraries.

Recently Resolved Issues

The VDDK 6.7.0 EP1 release resolves the following issues:

  • Open SSL library upgraded.

    The Open SSL library openssl was upgraded from version 1.0.2n to version 1.0.2o because of a known security vulnerability.

  • HotAdd backup performance improved.

    A partner reported that HotAdd backup was slower in VDDK 6.5.2 than in VDDK 6.5, and determined that “thread a28” was checking disk status too frequently. The fix was to check status only for the disk to be opened.

  • VDDK failed to open disk with NBDSSL when using auto transport mode.

    When a program allows auto transport mode and there is mode fall-back (from SAN to NBDSSL or from HotAdd to NBDSSL, etc.), NBDSSL or NBD mode cannot work because of a missing SSL thumbprint. The fix was fetching a new token to acquire the SSL thumbprint.

Known Issues and Workarounds

This issue was reported by partners after the 6.7 release.

  • NBD transport in VDDK 6.7 is slow when running against vSphere 6.5.

    When data protection software is compiled with VDDK 6.7 EP1 libraries, NBD mode backup and restore is significantly slower than before on vSphere 6.5 or 6.0. This regression was caused by dropping the OPEN_BUFFERED flag when it became the default in VDDK 6.7. The OPEN_BUFFERED flag will be reintroduced in VDDK 6.7.1 for backward compatibility. When performance is important, VMware recommends use of NBD Asynchronous I/O, calling VixDiskLib_WriteAsync and VixDiskLib_Wait.

For issues in the VDDK 6.7 release, see the VDDK 6.7 Release Notes.