Unable to copy the virtual machine disk using the VMware VixDisklib .

Problem

Backup of a VMware virtual machine fails with the error "V-79-57344-38264 - Unable to copy the virtual machine disk using the VMware VixDiskLib.

Error Message

V-79-57344-38264- Unable to copy the virtual machine disk using the VMware VixDiskLib.

VixDiskLib_Read() reported the error: Unknown error

Beremote.log from the Backup Exec server shows.

[fsys\vmvcb]         - VM_VCBPROXY_FS::GetNextDiskChangeInfo() Node name: 'DiskChangeInfoResult' startoffset: (0x00000000)  startlength: (0x42949672960)
[fsys\vmvcb]         - VM_VCBPROXY_FS::GetFirstDiskChangeInfoExtent() Node name: 'ChangeArea' offset: (0x00000000)  length: (0x01048576)
[fsys\vmvcb]         - VM_VCBPROXY_FS::GetNextDiskChangeInfoExtent() Node name: 'ChangeArea' offset: (0x01048576)  length: (0x3313041920)
[fsys\shared]        - VDDK-Log: NfcNetTcpRead: timed out waiting for data
[fsys\shared]        - VDDK-Warn: [NFC ERROR] NfcFssrvrRecv: failed with code = 9
[fsys\shared]        - VDDK-Warn: [NFC ERROR] NfcFssrvr_DiskIo: failed to receive read data
[fsys\shared]        - VDDK-Log: DISKLIB-LIB   : RWv failed ioId: #3914 (290) (34) .
[fsys\vmvcb]         - VM_VCBPROXY_FS::ReadObj() Could not read the disk '[LUN] VM-NAME/VM-NAME.vmdk' start Sector: '500038', Num of sectors: '128' Error Text: 'Unknown error' Error: '1245540515841'
[ndmp\loops]         - LP_ENV::MsgError: error 0xe0009578 processing object VM-NAME/VM-NAME.vmdk
[fsys\shared]        - VDDK-Log: NfcNetTcpRead: timed out waiting for data
[fsys\shared]        - VDDK-Warn: [NFC ERROR] NfcFssrvrRecv: failed with code = 9
[fsys\shared]        - VDDK-Warn: [NFC ERROR] NfcFssrvr_Close: failed to receive reply to close message
[fsys\brfs]          - brUtil::GetSpecialObjectStream() - No special objects

Cause

This is a network related problem that results in an I/O error when an attempt to download a file from datastore is made.

Solution

To resolve the issue disable NetDMA (Network Direct Memory Access) feature on the Backup Exec server.

netsh int tcp set global netdma=disable

Note: To enable or disable the debug logging in Backup Exec, refer to following article:

How to enable Debugging to troubleshoot Agent for VMware Virtual Infrastructure (AVVI) backup\restore issues