Lotus Notes backups from a Domino Server in DMZ, write successfully to any device as long as the backup last less than 30 minutes. Beyond 30 minutes, the backup fails, while shorter backups succeed.
File System backups from the same Domino server always complete successfully no matter how long they last.
When the Lotus Domino backups fail, the Plugin for Domino crashes.
The NetVault binary log shows:
Information 2014/02/14 11:33:53 N/A GUI NVSERVER User 'default' Job id 495 on MAIL rescheduled for immediate execution
Error 2014/02/14 12:03:54 495 Jobs NVSERVER Job manager lost message channel unexpectedly
Channel '00885D38': process ID '3' connected to process ID '297' running on 'MAIL' has been lost.
Trace on the Plugin for Domino shows the following before the plugin crashes:
> 0 NET ??? 5208 84 0 120354673250 Connection down
> 5 MESSAGE ??? 5208 53 0 120354673250 NetTcpReceive returned unknown error
Suggesting the transfer is being interrupted from an unknown source.
NetVault backups of database applications are known as "multistream" backups.
The NetVault database plugins will send the various data types that constitute the databases into different streams, either simultaneously of sequentially. When the streams are sent one after the other (sequentially), NetVault will reuse the same connection as the first stream when starting the second stream, and this is done in rapid successions.
This behaviour of rapidly reusing the same connections can raise some firewall's alarms, suspecting Denial of Service attacks, and the re-connections attempts are blocked.
In this case, a NETASQ firewall was used that had a TCP timeout Stateful inspection mechanism that prevents rapid reuse of connections. When the first stream finished after 30 minutes, the second stream was always blocked during reuse of the initial connection.
When backing up via firewall ensure TCP timeout and Stateful inspection settings are flexible enough to allow rapid re-use of connections during mutlitstream backups.
Check with your Firewall vendor on how to configure these setting and multistream backup should then succeed.
