NVP-vProxy: Backups Intermittently Fail with "Memory allocation failed. Out of memory"
Summary: The VMware workflow intermittently encounters a few random virtual machine failures during the scheduled execution with out of memory messages.
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Symptoms
The NetWorker VMware Protection integration is configured with the vProxy Appliance.
The VMware workflow intermittently encounters a few random virtual machine (VM) failures during the scheduled execution.
A subsequent execution of the VM completes successfully.
The backup workflow log shows:
The VMware workflow intermittently encounters a few random virtual machine (VM) failures during the scheduled execution.
A subsequent execution of the VM completes successfully.
The backup workflow log shows:
YYYY/MM/DD HH:MM:SS TRACE: [215] "Hard disk 1": VddkBlockReader: starting go routine ...
YYYY/MM/DD HH:MM:SS TRACE: [215] "Hard disk 1": VimDiskRegionReader: starting go routine ...
YYYY/MM/DD HH:MM:SS ERROR: [215] "Hard disk 1": VddkBlockReader: VDDK Error: 2: Memory allocation failed. Out of memory..
YYYY/MM/DD HH:MM:SS ERROR: [215] "Hard disk 1": VddkBlockReader: failed reading from "Hard disk 1" at sector 4955136.
YYYY/MM/DD HH:MM:SS TRACE: [215] "Hard disk 1": VddkBlockReader: sent VDDK read error on error channel.
YYYY/MM/DD HH:MM:SS INFO: [215] "Hard disk 1": VddkBlockReader: finished go routine.
Cause
The VMs were all using the Network Block Device (NBD) transport for the scheduled execution and were exhausting the ESXi host resources during the scheduled execution. The NBD transport uses the network to transfer the VMware change blocks to the vProxy and is less efficient than the HOTADD transport.
The vProxy used has NBD sessions enabled (nonzero value). The VM backup session log shows that the transport method used was NBD.
The vProxy used has NBD sessions enabled (nonzero value). The VM backup session log shows that the transport method used was NBD.
Resolution
Solution:
It is recommended to use the
See the NetWorker VMware Integration Guide regarding
Workaround:
Migrate the VM to another available ESXi host in the same cluster and perform the backup.
It is recommended to use the
HOTADD transport to perform the vProxy backups. If the NBD transport is required, the number of NBD sessions should be reduced during the scheduled execution.
See the NetWorker VMware Integration Guide regarding
hotadd requirements.
Workaround:
Migrate the VM to another available ESXi host in the same cluster and perform the backup.
Article Properties
Article Number: 000044543
Article Type: Solution
Last Modified: 15 Oct 2025
Version: 4
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