Archiving task fails to connect exchange server when the connection is routed via Network Load Balancer (NLB)

Problem

When starting an archiving task (Mailbox archiving, Journal or Public Folder), the task fails within a few minutes. Depending on the configuration of Enterprise Vault, there may be a number of different event ID's logged in the Veritas Enterprise Vault event log.

Error Message

All failed tasks experiencing this issue will log the Event ID 3305:

Event ID: 3305
Description: 
The Task '<Archiving Task>' failed to log on to Exchange server '<servername>' using mailbox 'mailbox@domain.com'.
Please ensure that the server is running and that the Vault account has sufficient permissions on the server.
V-437-3305

If a Mailbox Archiving Task is configured then the event ID 2256 will be logged:

Event ID: 2256
Description:
The Archiving task '<Mailbox Archiving Task>' could not be started due to startup errors.
V-437-2256

If a Journal Task is configured then the event ID 2258 will be logged:

Event ID: 2258
Description: 
The Journal Task '<Journaling Task>' could not be started due to startup errors.
V-437-2258
 

If a Public Folder Task is configured then the event ID 2949 will be logged:

Event ID: 2949
Description:
The Public Folder Task '<Public Folder Task>' could not be started due to startup errors 
V-437-2949

A Dtrace of the relevant archiving task (ArchiveTask, JournalTask or PublicFolderTask) shows:

     Could not open message store: [0x8004011d]

A Netmon Log Shows:

     Status: 0x1C010014 nca_server_too_busy - The server is too busy to handle the call.

UMI Code: V-437-41443

Cause

Enterprise Vault is unable to establish a MAPI connection due to restrictions imposed by the configuration of a Network Load Balancer (NLB).

Solution

Solution 1:

Configure the Network Load Balancer to allow the connection using all ports between the Enterprise Vault Server and Exchange Client Access Server (CAS).

Or

Use Static port mapping for MAPI connection and open that port in the Network Load Balancer.

Refer to Configuring Static RPC Ports on an Exchange 2010 Client Access Server to check whether the exchange is configured for static port mapping.
 

Solution 2:

Increase the default TCP Session Timeout on the applicable Load Balancing Appliance.

Note: For further assistance to increase this timeout value, please contact the appliance vender.
 

Solution 3

If the ports and TCP Session Timeout are correctly configured as above then refer to the Related Article 000014596 below for additional steps.