Virtual Disk Development Kit Release Notes

Release Date: 11 APR 2019 | ESXi build 13010696, VDDK build 13015725
For vSphere 6.7 Update 2 | Last document update 3 JUL 2019
Check for additions and updates to these release notes.


About the Virtual Disk Development Kit

The Virtual Disk Development Kit (VDDK) 6.7.2 is an update to support vSphere 6.7 Update 2 and to resolve issues discovered in previous releases. VDDK 6.7 added support for ESXi 6.7 and vCenter Server 6.7, and was tested for backward compatibility against vSphere 6.0 and 6.5.

VDDK is used with vSphere Storage APIs for Data Protection (VADP) to develop backup and restore software. For general information about this development kit, how to obtain the software, programming details, and redistribution, see the VDDK landing page on VMware {Code}.

The VMware policy concerning backward and forward compatibility is for VDDK to support N-2 and N+1 releases. In other words, VDDK 6.7 and all its update releases support vSphere 6.0, 6.5 (except for new features), and the next major release.

Changes and New Features

VDDK 6.7.2 library on Linux systems now supports:

  • Improved blacklist performance.
  • Adapts to vCenter Server single/double URL decoding.

In addition to those previously qualified for use as a backup proxy, the following operating systems were tested with VDDK 6.7.1:

  • Red Hat Enterprise Linux RHEL 6.9
  • CentOS 7.4
  • SUSE Linux Enterprise Server SLES 15
  • Windows Server 2016 version 1803
The following operating system was tested and added for VDDK 6.7.2:
  • SUSE Linux Enterprise Server SLES 12 SP4

For new features in VDDK 6.7, see the Virtual Disk Development Kit 6.7 Release Notes. For VixMntapi enhancements, see the Virtual Disk Development Kit 6.7.1 Release Notes.

Compatibility Notices

In earlier releases it was an error to close parentHandle after VixDiskLib_Attach succeeds. The VDDK library now marks parentHandle internally to prevent closure and ensure cleanup. See the VDDK 6.7.1 Release Notes for coding advice.

Recently Resolved Issues

The VDDK 6.7.2 release resolves the following issues.

  • Windows mount library could crash during asynchronous I/O.

    When doing asynchronous I/O, the Window VixMntapi library could crash with a log message indicating PANIC at diskLib.c line 4086. This was caused by two operations in the wrong order, now fixed in VDDK 6.7.2.

  • XML library upgraded.

    The XML library libxml2 was upgraded from version 2.9.8 to version 2.9.9 because of a known security vulnerability.

  • Open SSL library upgraded.

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

  • Disk open fails in HotAdd mode if datastore name contains special characters.

    When datacenter or datastore name contain special characters, such as parentheses or even space, disk open can fail in HotAdd mode. This occurs when VDDK calls HttpFileService because NoNfcSession is set to 1. The cause is the difference between double URL decoding used previously, and backward-incompatible single URL decoding used in vSphere 6.7, 6.7 U1, and Cloud M5. The issue is fixed in vSphere 6.7 U2 by first using double URL decoding, then trying single URL decoding if datacenter or datastore names do not match.

  • Snapshot consolidation may fail after SAN backup.

    If the ddb.adapterType in the VMDK descriptor file is invalid, for example “legacyESX” adapter type, VDDK fails to consolidate snapshots after SAN mode backup. The workaround (or fix) was to change ddb.adapterType to a valid value, such as lsilogic, ide, or buslogic. VDDK 6.7.2 contains cleanup code to resolve this issue, which has existed for many releases.

  • TCP session established by ConnectEx fails to close after Disconnect.

    TCP sessions created from vCenter Server by VixDiskLib_ConnectEx and VixDiskLib_Open sometimes do not get closed even after calling VixDiskLib_Close, VixDiskLib_Disconnect, and VixDiskLib_Cleanup. TCP sessions do get closed by VixDiskLib_Exit, but only after resource leakage has occurred. This issue is fixed in this release by making weak cyclic connections, which (unlike strong connections) the watchdog is able to close.

Known Issues and Workarounds

These are unresolved issues known at this time.

  • vSphere 6.7 HTTP File Service not backward compatible until 6.7 U2.

    This is related to “Disk open fails in HotAdd mode if name contains special characters” above. Backup partners with on-prem customers running VDDK 6.7.0 or VDDK 6.7.1 can recommend the NoNfcSession=0 setting to work around the problem, and urge an upgrade to VDDK 6.7.2 when feasible. Partners with cloud-based customers should make upgrade to post M5 and VDDK 6.7.2 mandatory, because NoNfcSession=1 must be set for security reasons. Partners using the Http_Access API in their own programs should code a fix to support multiple vCenter versions with adaptive single and double decoding. This issue will be permanent for partners supporting vSphere 6.7, 6.7 U1, and M5.

  • Multiple SCSI controllers on a Linux backup proxy.

    When a Linux backup proxy VM contains multiple SCSI controllers, HotAdd transport might not able to recognize all disks correctly. See KB 67757 Best practice for Linux proxy VM configuration in HotAdd transport for discussion and workarounds.