Slow VMware restore performance using NBD transport mode.

Problem

Customers may observe restore job takes more time with vSphere 7.0 and later comparing to older vSphere version.

Error Message

N/A

Cause

Refer following VMware articles for details. It is confirmed that the same apply to restores as well.

  Impacted performance over NBD/NBDSSL (86269)
  Backup speed is slow over NBD transport mode for VMs on high-latency storage (83401)  

Solution

Upgrade to NetBackup 10.0 and configure NFC (Network File Copy) AIO (Asynchronous I/O) buffer options with the following steps.

1) On the backup/restore host, copy vixDiskLib.ini to the following directory.

  Windows Backup Host:
  From:  <NetBackup install path>\NetBackup\bin\goodies\vixDiskLib.ini
  To: <Windows install drive>\Program Files\Common Files\VERITAS\VxMS\Shared\VDDK\bin\

  Linux Backup Host:
  From:  <NetBackup install path>/netbackup/bin/goodies/vixDiskLib.ini
  To: <NetBackup install path>/lib/shared/vddk/lib64

2) Open the copy of vixDiskLib.ini with text editor.

  Windows Backup Host:
  <Windows install drive>\Program Files\Common Files\VERITAS\VxMS\Shared\VDDK\bin\vixDiskLib.ini

  Linux Backup Host:
  <NetBackup install path>/lib/shared/vddk/lib64/vixDiskLib.ini

3) Edit vixDiskLib.ini as only contains following parameters and save.

NOTE: The default vixDiskLib.ini contains LogLevel parameters and leaving these in place will increase logging.

vixDiskLib.transport.LogLevel = 6    <<<---- REMOVE THIS LINE IN THE COPIED FILE

vixDiskLib.nfcAio.Session.BufSizeIn64KB = 16

vixDiskLib.nfcAio.Session.BufCount = 4

4) This should take effect on the next restore, so after applying the workaround start a new restore and compare the performance.

For granular details you will require BPTM and VxMS logging.

Related Articles:

VMware backup fails with status 6 after VDDK upgrade.