Configuring the Transport Dumpster
When deploying a CCR-based cluster in your environment, an important step is to enable the Transport Dumpster on the Hub Transport server.
The Transport Dumpster is a new feature of the Exchange 2007 Hub Transport server that can submit recently delivered mail after an unscheduled outage. For an e-mail message to be able to be retained in the Transport Dumpster, at least one of the message recipients must have his or her mailbox located on a CCR-based mailbox cluster server, because the Transport Dumpster works only with mailboxes located on a CCR-based mailbox server cluster. As mentioned earlier in this chapter, with CCR the replication of mailbox data from the active node to the passive node is asynchronous, which means that the passive node will always lag behind the passive node (although not by much). This means that should a failure of the active node occur, there's a chance that not all transaction log files will have been replicated to the passive node before this happens. This is where the Transport Dumpster comes into the picture. It can resubmit recently delivered mail and thereby constitute for the majority of the changes in the database(s). When a failure of the active node results in a lossy failover to the passive node, the cluster mailbox server will ask all the Hub Transport servers in the site to redeliver any lost mail.
| Note: Should any of the messages that are being resubmitted to the cluster mailbox server be duplicates, the store is intelligent enough to discard any duplicates it finds. |
The Transport Dumpster is enabled by default; you can see the default configured settings by running the Get-TransportConfig CMDlet.
Microsoft recommends that you configure the MaxDumpsterSizePerStorageGroup parameter, which specifies the maximum size of the Transport Dumpster queue for each storage group to a size that is 1.25 times the size of the maximum message that can be sent. For example, if the maximum size for messages is 10 megabytes (MB), you should configure the MaxDumpsterSizePerStorageGroup parameter with a value of 12.5 MB.
In addition, Microsoft recommends that you configure the MaxDumpsterTime parameter, which specifies how long an e-mail message should remain in the Transport Dumpster queue, to a value of 07.00:00:00, which is seven days. This amount of time is sufficient to allow for an extended outage to occur without loss of e-mail. When you use the Transport Dumpster feature, additional disk space is needed on the Hub Transport server to host the Transport Dumpster queues. The amount of storage space required is roughly equal to the value of MaxDumpsterSizePerStorageGroup multiplied by the number of storage groups.
You use the Set-TransportConfig CMDlet to enable and configure the Transport Dumpster. So, for example, to configure the maximum size of the dumpster per storage group to 25 MB with a dumpster life of 10 days, you would need to run the command Set-TransportConfig -MaxDumpsterSizePerStorageGroup 25MB -MaxDumpsterTime 10.00:00:00.
To see the MaxDumpsterSizePerStorageGroup and MaxDumpsterTime configuration settings, you can type Get-TransportConfig, as shown in Figure 8.65.
Figure 8.65 Transport Configuration Settings. (Click on image for enlarged view.)
Managing an Exchange 2007 Cluster Continuous Replication (CCR) setup
Part 1: Exchange 2007 Cluster Continuous Replication requirements
Part 2: Setting up Cluster Continuous Replication in Exchange 2007
Part 3: Creating a Windows 2003 cluster for an Exchange 2007 CCR setup
Part 4: Using a file share witness with Exchange 2007 CCR
Part 5: Enable the Transport Dumpster on the Hub Transport server
Part 6: Installing Exchange 2007 on the active node and passive node
Part 7: Testing clustered mailbox server functionality in a CCR setup
Part 8: Exchange 2007 Cluster Continuous Replication (CCR) setup overview
