Backup to smartdisk fails with Backup Lost Message Channel Unexpectedly (4047110)

Date: AUG 2010
Product & Version: Smartdisk
OS Version: Windows 2003

Symptoms:

Backups to smart disk fail. First we see "Transfer to the device has stalled" messages the eventually we see "Backup Lost Message Channel Unexpectedly" and the backup fails. See binary log example below:


Job Message 2010/08/17 14:33:17 773 Media NVBACKUP Job has been assigned device 'SmartDisk - backupsvr1'
Information 2010/08/17 14:33:17 773 Data Plugin NAVISION Connected to DAV server 'backupsvr1' at address '10.2.250.193', port '37453'

Warning 2010/08/17 16:20:03 773 Data Plugin NAVISION Transfer to the device has stalled
Warning 2010/08/17 16:20:03 773 Data Plugin NAVISION Transfer to the device is no longer stalled
Warning 2010/08/17 16:24:20 773 Data Plugin NAVISION Transfer to the device has stalled
Warning 2010/08/17 16:24:34 773 Data Plugin NAVISION Transfer to the device is no longer

stalledError 2010/08/17 16:33:38 773 Jobs NVBACKUP Job manager lost message channel unexpectedly
Error 2010/08/17 16:33:46 773 Jobs NVBACKUP Fatal error: Backup Lost Message Channel Unexpectedly
Error 2010/08/17 16:33:46 773 Jobs NVBACKUP Job Status: Backup Failed




Cause:
When backups fail like this tells there is a communication problem between netvault server and the Smartdisk

15 seconds
Index

Increase the block transfer size from default 32KB to at least 256KB

smartdisk.bat config --update --webdav 37453 --block-size 262144


Explanation:
It appears that bigger packets on certain networks help smartdisk stream data more effectively therefore reducing the number of times the device need to stall and stopping the message channel from dropping


Prepared by: Richard Downes