Geographically Distributed Clustering

Data Replication and Mirroring
BrightStor High-Availability Manager uses replication tasks to define which data needs protection. You use the console's Replication Task Wizard to set up a new replication task. The wizard prompts you to select the server you want to protect, choose the server that will hold the replicated data, and choose from a range of network speeds for the link between the two servers. The wizard also prompts you to choose between Full Protection (with failover capabilities) and Data Protection Only and to select the folders to be replicated. I tested only the Full Protection option. Next, the wizard guides you through configuring communication-failure detection parameters, then displays a summary screen that contains details about the replication task you defined. From the summary screen, you can click Advanced Edit to open the Task Editor, which lets you view and modify a given task's steps. Finally, the wizard prompts you to start the new replication task.

Octopus offers five templates—called specifications—to help you define data-replication parameters. You use the Octopus Client, which Figure 1 shows, on the source computer to choose a specification. The File/Directory specification replicates specific files, shares, or directories. The Global Exclude specification, which takes precedence over all other specifications, lets you exclude certain files from replication. The Share specification replicates shares but not the contents of those shares. The Registry specification lets you replicate registry data to the secondary server. The DFS specification (for NT only) lets you define DFS shares that you want to replicate. After you choose one of the specifications and select the objects that you want to replicate, the software displays an Options dialog box, in which you can fine-tune file-protection, -permission, -deletion, and -exclusion characteristics. Finally, in the Synchronization window, you choose when and how to synchronize the data that will be replicated.

The first time you open Double-Take's Management Console, the software launches the Connection Wizard. This wizard helps you establish your source and target servers and configure a Replication Set. When the wizard is finished, you can click Advanced Options to bring up the Connection Manager window, in which you can adjust mirroring, scheduling, and failover options. If you want to deploy this product in a bandwidth-limited environment, you'll find Connection Manager's Transmit tab particularly interesting: On this tab, you can set bandwidth percentage limits, time limits, and byte limits to throttle bandwidth usage. Of the three tested products, Double-Take offers the most bandwidth control. After you close the Connection Manager window, the new Replication Set appears in the Management Console.

Failover Methods
How well the products detect a failure, perform the failover, and permit you to reinstate a repaired server directly determine the value that the products offer to your organization. For a comparison of key features, see Table 1, page 68.

Octopus can automatically transfer processing from a source system to a target system if the source system fails. Failure detection occurs through heartbeat communication between nodes; if you need more advanced triggering, you can use a third-party systems management application to monitor your systems and execute scripts to perform actions when necessary.

   Previous  1  [2]  3  4  5  Next