Graceful handling of computer sleeping mid backup (iscsi race condition?)

Urbackup seems to have an issue where the server will soft lock if the client backing up goes to sleep midway through a backup.

This scenario happens when the UrBackup server is self-hosted on the same machine where the backup is being performed.

The symptoms are as follows:

  1. The server and client seemed to still think a backup is still in progress.
  2. Backup progress however holts with no further movement.
  3. Pausing and resuming does not work, the server recognises a pause command is sent and states paused, but when resumed still does not continue receiving backup data.
  4. ETA skyrockets to ludicrous number of hours / days / years.
  5. Restarting the UrBackupClientBackend service snaps the client out of it, and states there is no current backup operating.
  6. However, the server still thinks there is a backup in operation on the client machine under the activity’s tab.
  7. The only way to fix seems to be restarting UrBackupWinServer service.
  8. Client does not report any errors or warnings in its logs, however the server does show a few that are as follows:

(Note: Anything with ***text*** has been redacted for privacy.)

Error opening file 
for reading file. File: temp_fn. The system cannot find the path specified. 
(code: 3) Target path: 

This error is repeated 16 times with various files, but the basis is the same.

Error opening file:

Target path: N:

DEBUG Metadata file and "N:\UrBackup\***computerName***\230326-1224\***user***
(id=487388) do not exist. Skipping applying metdata for this file.

DEBUG max_downloaded=488092 max_preprocessed=488686 min_downloaded=488686
postponed. Size=0`

  1. There are no more logs after this and there is just a spinning wheel.
  2. Clicking stop in activities also outputs the following error:

ERROR  	Error reading from file \\?\N:\UrBackup\urbackup_tmp_files\3. 
The device is not ready. (code: 21)`
INFO  	Waiting for file transfers...

However, this file is accessible from that drive when checking in explorer. it seems to just get stuck at this point.

My setup consists of the following

  • Client 2.5.23,
  • Server 2.5.28.
  • OS: Windows 11 22H2 on build 22621.1413
  • The files are being backed up off of a local storage spaces drive, onto a NAS drive that is using iscsi.

My current working theory.

There is a race condition when the computer wakes up, where UrBackup attempts to continue backing up, but the iscsi initiator has not re-established the connection with the NAS drive yet.