Configuring the Majority Node Set Quorum with File Share Witness
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No doubt some of you are thinking: What the heck is a Majority Node Set quorum with File Share Witness? We can understand why; this is a completely new type of quorum model that is made available by installing the update (MS KB article 921181) mentioned in the beginning of this chapter section. The update makes it possible to use a file share witness that is external to the cluster as an additional "vote" to determine the status of the cluster in a two-node MNS quorum cluster deployment, which is a requirement for using the CCR functionality in Exchange Server 2007.
The file share for this file share witness can be located on any type of Windows server in your environment, but best practice is to use an Exchange 2007 Hub Transport server in the Active Directory server site containing the nodes in the respective cluster. We'll also use a Hub Transport server in this example.
The first thing you need to do is to create the file share on the Hub Transport server. You can do this either via the CLI or by using the GUI. In this example we'll use the GUI:
- Log on to the Hub Transport server with a domain admin account, then open Windows Explorer and create a new folder called MNS_FSQ_E2KTCCR on the C: drive or wherever you want it to be created, as shown in Figure 8.58.
- Now open the Properties page for the newly created folder and click the Sharing tab (see Figure 8.59).
- Click Permissions and configure the share permissions so that only the Cluster Service Account is allowed access to this share (see Figure 8.60).
- Click OK, then select the Security tab. Here you should give Full Control to the local administrator and the cluster service account, as shown in Figure 8.61. Make sure you clear Allow inheritable permissions from the parent to propagate to this object and all child objects when doing so, then click OK twice and log off the server.
- Back on EDFS07 or EDFS08, we now need to set the Majority Node Set Private Property attribute to point to the file share we just created. We do so by opening a command prompt, then issuing the command Cluster res "Majority Node Set" / p r i v MNSFileShare=\\EDFS03\MNS_FSQ_E2K7CCR.
- To force all changes to take effect, we will move the cluster group from one node to the other (taking the cluster group offline and online again). Do this using the command Cluster Group "Cluster Group"/Move. When you have done so, you will see that the cluster group is now online on E2K7Node2, as shown in Figure 8.63.
- Now let's verify that the 7Priv property is set correctly. This can be done by issuing the command Cluster Res "Majority Node Set"/Priv.
|Note: It's recommended that you use the MNS_FSQ_clustername naming convention when you create this folder.|
|Note: Make sure to replace the server name so that it matches the name of the Hub Transport server in your environment.|
You will get a warning that all properties were stored but not all changes will take effect until the next time the resource is brought online, .just as is shown in Figure 8.62.
|Some Independent Advice: In a couple of the CCR-based cluster deployments I've done, I have gotten an error message similar to the following when running the command Cluster res "Majority Node Set" /priv MNSFileShare=\\EDFS03\ MNS_FSQ_E2K7CCR:
Too many command line parameters have been specified for this option.
Should you experience this error, too, you should be able to get going using the following command syntax instead:
As you can see in Figure 8.64, this property has been set correctly for the purposes of our example.
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.
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
|This chapter excerpt from How to Cheat at Configuring Exchange Server 2007: Including Outlook Web, Mobile, and Voice Access , by Henrik Walther, is printed with permission from Syngress, a division of Elsevier, Copyright 2007.
Click here for the chapter download.