Chapter 3: Protecting an Exchange Server
3.10 Saving configuration changes
After you have changed the configuration parameters, click OK to apply the settings. If you click Cancel, any changes you have made will be discarded and the previous configuration parameters will be used.
When you have finished configuring the optional protection options, continue with Validate the Configuration on page 78.
NOTE: If you close the Double-Take Application Manager prior to enabling protection, your changes will not be saved.
You must enable protection in order to save your configuration settings for a source/target pair.
Protecting an Exchange Cluster with a Like-Named Cluster
This section describes the process used to configure protection for an Exchange 2003 cluster with a like-named (also known as a “standby”) cluster.
When you protect a cluster with a like-named cluster, the Double-Take Application Manager moves the EVS (Exchange virtual server) location from the source cluster to the target cluster. By moving the EVS, the process of moving users and public folders from one server to another is not needed, because they will continue to use the same mail store on the target as they were on the source. This, coupled with the ability to reduce the TTL (Time to Live) value of the EVS DNS record (optional), allows a more seamless failover.
4.1 Prerequisites
Before you can use the Double-Take Application Manager to protect a cluster with a like-named cluster, you must complete the following:
Each target server node must have the same version and service pack level of Exchange as is installed on the source nodes.
The target must have a resource group that has the same name as the resource group on the source.
The target resource group only needs to contain physical disk resources, which MUST use the same drive letters that are used by the physical disk resources on the source.
4.2 Permissions
When protecting a cluster with a like-named cluster, you can perform the setup, failover, and failback with the following permissions:
The user must be a member of the local “Double-Take Admin” group.
The user must be a member of the cluster Administrator group.
The user must be delegated Exchange View Only access through Exchange System Manager.
(Optional) In order to change the TTL within DNS during failover, the user must be a member of the DnsAdmins group.
4.3 Multiple EVS
The instructions in this chapter also apply to setting up multiple EVS. To use multiple EVS, set up multiple like-name jobs for each EVS on your source cluster.
NOTE: Like-named cluster support is only available for clusters running Exchange 2003.
NOTE: Because the first installed EVS is the only one that has the MTA resource (Message Transfer Agent), if you do not failover all Exchange virtual servers, then any user who is in a different mail store than the first one will not be able to route mail.
4.4 Standby cluster configuration
The process for protecting a cluster with a like-named cluster is similar to protecting a standard cluster. The following instructions point out the differences in configuration. For more information about basic protection functions, see the section Protecting an Exchange Server.
1. In the Source Server field, select the source cluster that you want to protect.
2. In the Target Server field, select the same server.
3. After you select a like-named cluster for the target, you will need to configure the like-named cluster. After you select the target server, the Like-named cluster setup dialog box will appear.
NOTE: The server name will be appended with the suffix “(like-named)”
4. Enter the following information:
Target Cluster—Enter the name of one of the target nodes, then click Connect.
Network—Select the NIC to which you will assign the IP.
IP Address (to create)—Enter a new IP address for the target to use when it stands in for the source.
Subnet Mask—Enter the subnet mask to use for the new IP address.
Storage Resources—The Application Manager will automatically select the required storage resources on the target, provided that they exist (for example, if the source and target both have E:\ and S:\). Verify that the drive letters where Exchange data is located are selected.
5. When you are finished, click OK to return to the Manage Exchange window.
6. On the Manage Exchange window, click Configure to open the Configure Protection window, then select the Failover tab.
7. DNS Failover is the only option available for configuring protection with like-named clusters. For more information about DNS failover, see DNS failover on page 17.
NOTE: You can not de-select a storage resource that exists on both the source and target.
If the drive letters on the source and target do not match, then not all required data will be selected automatically. You will need to select it manually. The selected storage resources must be in the same group.
8. If you want to modify DNS configuration options, click Configure. The Configure DNS Failover window will appear.
9. On the Configure DNS window, you can modify the TTL value for the DNS record. You can also specify the user credentials needed to modify DNS. When you are finished, you can click Test to test the DNS configuration for the selected DNS server(s), or click OK to return to the Configure Protection window.
10. After you have changed the configuration parameters, click OK to apply the settings and return to the Manage Exchange window. If you click Cancel, any changes you have made will be discarded and the previous configuration parameters will be used.
11. Click Validate to validate the selected cluster pair. The validation proceeds exactly like validation for other methods of failover.
12. Click Enable Protection to enable protection for the source cluster.
4.5 Enabling protection
After protection is enabled, the Double-Take Application Manager creates four resources on the target cluster: two generic script resources, an IP address resource, and a temporary name resource. The temporary name resource is the source EVS name with “_LN” appended to the end. The Application Manager uses the temporary name resource for the connection between the source and target clusters. The Application Manager gets the order of the source cluster resources from the Microsoft Cluster DLL, then builds the scripts with the resources in order and based off the source’s resources configuration.
After the four resources are online and the mirroring has completed, the source cluster is considered protected and the Application Manager starts monitoring the source for complete source failure.
NOTE: Decreasing the TTL value will increase the speed at which clients get the updated information.
NOTE: Three scripts are automatically generated by the Application Manager during configuration. The scripts are copied to the Double-Take installation directory on the specified server using the administrative share for that server’s drive.
Failover Script—A post-failover script (post_failover_LN.txt) is executed after the core failover processes have completed on the target server. The primary function of the post-failover script is to start the resources on the target.
Failback Script—A pre-failback script (pre_failback_LN.txt) is executed before failback processing occurs on the target server. The primary function of this script is to stop resources on the target.
Restore Script—A post-restore script (post_restore_LN.txt) is not executed automatically, though it is provided on the source to perform actions that are generally required after data has been restored from the target to source after a failover/failback. The primary function of this script is to restart resources on the source server.
4.6 Dealing with a failure
4.6.1. Graceful failover
At the user's discretion, the Double-Take Application Manager can perform a graceful, or “soft” failover. A soft failover means the source cluster remains up and running while the EVS is transferred to the target cluster. This can be accomplished by using the failover button in Double-Take Application Manager. The steps the Application Manager takes to transfer the EVS from the source cluster to the target are the same as during a site failure failover, which is described in Site failure failover on page 32. The only difference is that in a soft failover, the source cluster resources are taken offline gracefully.
4.6.2. Site failure failover
If the Double-Take Application Manager detects that the source cluster has failed completely, it will display a prompt asking if a failover is desired. The time it takes for the Application Manager to realize a complete source cluster failure varies greatly.
At times, the prompt can be seconds after the failure, or, it might take several minutes. If you want the prompt to appear more quickly and you know that the source cluster has failed, you can decrease the amount of wait time by closing the Application Manager, then re-opening it.
When a failover is initiated, the following steps occur:
1. The Double-Take Application Manager waits on the target replication queue to empty.
2. The exchfailover.exe utility fails over the virtual protocols of the EVS.
3. The resources are created on the target cluster.
The resources are created in the same order as they appeared on the source cluster.
The resources are configured exactly as they were on the source cluster.
4. The resources are brought online.
5. The DNS failover utility is used to lock the source DNS record.
4.6.3. Differences in failback
The process used to failback to the source cluster is the same as any other cluster failover method. The only difference is the EVS is now on both the source and target clusters.
To failback to the source cluster, bring the source cluster online, then use the Double-Take Application Manager to failback.
NOTE: When you bring the source cluster online, an identical network name will still be active on the target. Because of this, when the source cluster tries to bring up the EVS on the source, the network name resource will fail and consequently the group will not come online on the source. You should allow the source cluster to finish trying to bring the resources online before using the Application Manager to failback.
Protecting a SQL Server
5.1 SQL configuration workflow
To configure protection for your SQL servers using Application Manager, you will complete the following steps:
1. Install SQL on the source server and apply any SQL service packs or patches. Use the default installation options for SQL.
2. Install SQL on the target, verifying that the installation location for the target is the same as the source. Apply any SQL service packs or patches. Use the default installation options for SQL with the following considerations:
The target must be a unique installation (that is, two SQL servers must be available for a protection pair)
Logical drive mapping must be the same on the source and target, and must assigned prior to running the Application Manager.
3. Install Double-Take on the source and target SQL servers. See the Double-Take Getting Started guide for more information.
4. Install the Double-Take Application Manager on page 8 5. Select a task on page 33
6. Select a domain on page 34
7. Select source and target servers on page 35
8. (Optional) Configure protection settings on page 37 9. Validate the Configuration on page 78
To protect your SQL server, you will complete the following steps:
1. Enable protection on page 79 2. Monitor protection status on page 80
In the event of a failure, you will need to perform some additional tasks. These tasks are described in Failover, Failback, and Restoration on page 85.
5.2 Select a task
To protect a SQL server, open the Application Manager (Start, Programs, Double-Take, Application Manager), then on the Tasks area on the left pane of the Double-Take Application Manager, select Protect SQL Server. The Manage SQL page will appear in the right pane. Make sure that the Setup tab is in view.
NOTE: You can also launch Double-Take Application Manager for SQL by using the command line /SQL option (DTAM /SQL).
If you have previously configured protection for a source/target pair, the Manage SQL page will be populated with information about the protected pair.
5.3 Select a domain
The Domain Name on the main window will be populated automatically with the domain where the Application Manager client resides.
If you want to change the domain, type in a domain name for a trusted domain that the Application Manager client can connect to, then press Tab or click on another field. If the domain you entered doesn’t exist or you do not have the credentials to modify Active Directory for the new domain, the Domain Login window will appear. You will be prompted to enter the domain name, user name, and password to use for logging in to the domain.
The user account should have administrator permissions. For more information about permissions, see Recommended Credentials on page 90.
NOTE: Domain names must include a suffix, such as .com, .corp, or .net.
You may enter a user name for a different domain by entering a fully-qualified user name. The fully-qualified user name must be in the format NetBIOS domain name\username or username. If you enter a non-qualified name, the default domain will be used.
5.4 Select source and target servers
If this is your first time to select a SQL server to protect, you may need to click the Advanced Find button to add servers to the Source Server and Target Server fields. For more information, see Add or manage servers on page 36.
If you select a source/target pair for which you have previously enabled and disabled protection, you may use the existing configuration settings (provided that the source/target connection is not currently active, in which case the existing settings will always be used). When you select Configure or Validate, a prompt will appear, asking if you want to re-use the previous configuration information. Click Yes to re-use the previous information, or click No to revert to the Application Manager default settings.
1. In the Source Server field, select the SQL server that you want to protect. If this is your first time to log in to the selected server, you will be prompted to enter server login information. For more information about logging in to servers, see Enter server login information on page 36.
2. In the Target Server field, select the backup SQL server that will protect the source server in the event of a failure.
Notice that after the source and target servers are selected, the Protection Status on the Monitor tab changes to
“Unprotected”.
NOTE: If the IP address(es) for the source or target server have changed since you originally configured protection (for example, if you configure the source or target in a staging area and then send it to a production location), you must re-configure the protection settings. When you are prompted to re-use the previous protection configuration, click No, then click the Configure Protection button.
NOTE: If you attempt to select a source that is currently unavailable, a prompt will appear stating that the source is not available and that if the source is failed over, you should first select the target.
If you select the target, then select the source (as recommended in the prompt), the same prompt appears (though you would expect to get a prompt to failover). The ability to failover using the Application Manager will not be available until a failover condition has been met in accordance with the failover monitor settings set in the configuration section.
NOTE: If you first select a target that is monitoring a connection that has met a failover condition and requires manual intervention, then select the protected source server, a prompt will appear, asking if you want to initiate failover.
5.4.1. Add or manage servers
If the servers you need do not appear, click the Advanced Find button, or select Actions, Manage SQL Servers. The Manage SQL Servers window will appear.
To discover all servers in the domain, click the Search button. The Discovered Servers list will be populated with all servers that the Application Manager can discover that reside in the domain.
To directly add a server to the drop-down list on the Manage SQL main page, select the server in the Discovered Servers list, then use the >> button to move it into the Current Servers list.
To add a non-discovered server to the Current Servers list, enter the server name in the field next to the Add button, then click the Add button.
After a server has been added to the Current Servers list, you can manage that server. Select the server, then select one of the following options:
Remove—Click the Remove button to remove the selected server from the drop-down list on the Manage SQL main page.
Test SQL—Click the Test SQL button to determine if SQL is installed and accessible for the selected server.
When you have finished adding, managing, or testing servers, click OK to save your changes, or Cancel to return to the Manage SQL main page without saving.
5.4.2. Enter server login information
After you select a server for the first time, you will be prompted to enter a user name and password to use for logging in to the selected server. The login account MUST be a member of the Double-Take Admin local security group for the selected server. For more information about permissions, see Recommended Credentials on page 90.
NOTE: In environments with a very large number of servers in Active Directory, you may experience significant delays while the Application Manager searches for SQL servers.
To override the automatic scan for SQL servers, you can launch Double-Take Application Manager through the command line using the /nosqlsearch option (DTAM /nosqlsearch). This will cause the Application Manager not to populate the Source and Target fields automatically. You will then need to click the Advanced Find button and add the source and target SQL servers manually.
You may enter a user name for a different domain by entering a fully-qualified user name. The fully-qualified user name must be in the format domain\username or username@domain. If you enter a non-qualified name, the DNS domain will be used.
Entering the credentials for the logged-on user may be valid.
The Application Manager will attempt to use the same user name and password the next time you select a server.
5.5 Configure protection settings
If you do not need to change the configuration settings, continue with Validate the Configuration on page 78.
If you have already enabled protection for a connection and need to change the configuration parameters, you will first need to disable protection, as described in Disable protection on page 80.
To change the default configuration parameters, click Configure from the main Application Manager window, or select Actions, Configure Protection from the menu. The Configuration Protection window will appear.
The Configure Protection window has tabs for configuring failover, connection, and advanced settings. The following sections describe the options on each of these tabs.
5.6 Failover settings
The Failover tab includes options that will be applied during SQL failover.
5.6.1. Failover enabled
Select the Failover Enabled option to enable or disable failover for the selected source/target pair.
Select the Failover Enabled option to enable or disable failover for the selected source/target pair.