vCenter Backup to SMB Share Fails with NT_STATUS_CONNECTION_DISCONNECTED and Broken Pipe
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vCenter Backup to SMB Share Fails with NT_STATUS_CONNECTION_DISCONNECTED and Broken Pipe

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Article ID: 447620

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Updated On:

Products

VMware vCenter Server

Issue/Introduction

vCenter Server file-based backups directed to an SMB target share fail mid-transfer. Disabling SEAT (Stats, Events, and Tasks) data does not resolve the failure. The /var/log/vmware/applmgmt/backup.log indicates the connection dropping during the transfer of backup components, exhibiting the following exact error sequence:

cli_push returned NT_STATUS_IO_TIMEOUT NT_STATUS_CONNECTION_DISCONNECTED [Errno 32] Broken pipe
[SMBClientStorageIOLib::isStorageCmdFailure:SMBClientStorageIOLib.py:220] ERROR: Command failed with error: NT_STATUS_CONNECTION_DISCONNECTED
[ComponentScriptsBackup:] [backupRestoreDispatch::RunBackupProcsPipeline:backupRestoreDispatch.py:] ERROR: Failed to write file to server
[SMBClientStorageIOLib::get_plugin_error:SMBClientStorageIOLib.py:81] ERROR: Command failed with error: NT_STATUS_CONNECTION_DISCONNECTED
[Proc::UpdateExceptionStatus:Proc.py:384] ERROR: Plugin error occurred. ErrCode: 6, Args: ()
[ComponentScripts::ComponentScriptsBackup:ComponentScripts.py:106] ERROR: Component backup command "/etc/vmware/backup/component-scripts/vum/backup_restore.py --startBackup" failed 1.
ERROR: Unable to perform backup: [Errno 32] Broken pipe
Backup job failed.

Environment

vCenter Server 7x, 8x, 9x

Cause

The backup process fails because the connection to the target SMB share times out and disconnects mid-transfer.

Specifically, the system attempts to write the backup data but encounters an I/O timeout (NT_STATUS_IO_TIMEOUT).

Because of this timeout, the connection is forcibly dropped (NT_STATUS_CONNECTION_DISCONNECTED), and the remote file being written to the SMB share (e.g. \destination_folder\vCenter_FQDN\M_8.0.3.00600_20260708-134312_\database_full_backup.tar.gz) is closed.

Once the target share disconnects, the internal archiving tool (tar) loses its destination pathway and subsequently fails with a broken pipe error (/usr/bin/tar: -: Cannot write: Broken pipe).

This identical disconnection sequence affects multiple backup components during the transfer, preventing successful completion.

Resolution

  1. Investigate the target SMB storage array for performance bottlenecks, connection limits, or aggressive idle-session timeouts that prematurely sever the data stream.

  2. Review the network infrastructure path between the vCenter Server and the SMB share to identify and eliminate packet loss, firewall session timeouts, or MTU mismatches.

  3. Configure a test backup using an alternative protocol, such as NFS, FTP, or SCP, to determine if the connection interruption is protocol-specific.

  4. Perform a manual backup to an alternative, geographically closer temporary target to isolate the backup mechanism from the existing network path.

Additional Information

Performing a Self-Backup of the vCenter for troubleshooting VAMI Backup issues

vCenter fails to back up to SMB server

Unable to change backup location in vCenter

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