Evaluation Guide Twelfth Edition (March 2009) Part Number: T2558-96326
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Table of Contents Chapter 1 Introduction .........................................................1-1 Storage Mirroring operations ............................................................ 1-3 Mirroring ............................................................................................................. 1-3 Replication ........................................................................................................... 1-4 Failure monitoring and failover ....................................
Introduction Storage Mirroring is a real-time data replication and failover software product. Storage Mirroring augments your existing data protection strategy by reducing downtime and data loss, and it provides these services with minimal impact on existing network and communication resources. Storage Mirroring allows you to specify mission-critical data that must be protected and replicates, in real-time, that data from a production server, known as the source, to a backup server, known as the target.
The following diagram is one common Storage Mirroring configuration. Production (Source) Servers High Availability (Target) Server Testing or Migration Server Offsite Disaster Recovery Server Centralized Tape Backup In this guide, you will find the following sections. 1. Introduction—A brief overview of 2. Resources—Resources available during your evaluation 3. Installation—System requirements and basic instructions for installing 4. Evaluation—Step-by-step instructions for evaluating 5.
Storage Mirroring operations Storage Mirroring performs four basic types of operations.
Replication Replication is the real-time transmission of file changes. Unlike other related technologies, which are based on a disk driver or a specific application, the Storage Mirroring replication process operates at the file system level and is able to track file changes independently from the file’s related application. In terms of network resources and time, replicating changes is a more efficient method of maintaining a real-time copy of data than copying an entire file that has changed.
Failure monitoring and failover Failover is the process in which a target stands in for a failed source. As a result, user and application requests that are directed to the failed source are routed to the target. Storage Mirroring monitors the source status by tracking network requests and responses exchanged between the source and target. When a monitored source misses a user-defined number of requests, Storage Mirroring assumes that the server has failed.
Restoration Restoration provides an easy method for copying replicated data from the target back to its original location on the source. The process only requires you to select the source, target, and the appropriate replication set. There is no need to select files or to remember where the data came from on the source since that information is maintained by Storage Mirroring.
Resources You have many resources available to you when using Storage Mirroring. Operating System and application documentation—Make sure that you have complete documentation for your operating system and your applications. Storage Mirroring documentation—All Storage Mirroring products include documentation. Manuals are available on the product CD (in the \docs subdirectories of each set of program installation files) and in the installation directory you selected during the installation.
Storage Mirroring Setup Your setup consists of two tasks: determining that your source and meet the system requirements of this evaluation and performing the installation. NOTE: When evaluating you should install and evaluate it in a test environment. Do not use your actual production servers because you will be forcing a failure during the evaluation. System requirements Storage Mirroring is an exceptionally flexible product that can be used in a wide variety of network configurations.
3. When the installation program begins, the Storage Mirroring Setup Launcher appears. This interface allows you to install and view documentation for various applications from HP. The listed applications will depend on which products are included on the CD or in the web download. To install Double-Take, select Storage Mirroring for Windows from the list of products and then select Install Storage Mirroring for Windows. 4.
Evaluating Storage Mirroring Storage Mirroring configuration consists of creating a replication set, which defines the data on the source machine that is to be protected, and then connecting that replication set to a target machine. These two steps, creation and connection of the replication set, are the backbone of the Storage Mirroring processes. From there you can also use Storage Mirroring failover, failback, and restoration processes for a high availability solution.
Checking your configuration Before starting your evaluation, make sure you have Storage Mirroring installed on the source and target. You should have at least 1 GB of data for testing. If you are going to be protecting application data, make sure the application is pre-installed on the target, but that the application services are not running. If the application services are running on the target, the files will be held open and Storage Mirroring will not be able to write to the files.
Monitoring the activity and completion of the initial mirror View your new connection in the Management Console by highlighting the source on the left pane. The connection will appear on the right pane. Use the horizontal scroll bar at the bottom of the right pane to view the various status columns. Pay attention to the Mirror Status column which shows the status of the mirroring operation. During the mirroring process, you will see a percentage of the mirror that has been completed.
Changing data to cause replication In order to test replication, you need to change the data on your source. This includes modifying existing files, creating new files, deleting files, and changing permissions and attributes. 1. On the source, browse through the directories and files contained in your replication set. 2. Select four files from your source and record the file information specified in the following table.
For complete details on all of the statistics, see the Storage Mirroring User’s Guide. NOTE: Many user applications typically save an entire file even though only a portion of the file may have changed. Therefore, the replication statistics will show the entire file being transmitted, not just the changed data.
Just like when you were monitoring the mirror and replication processes, you can monitor the verification process. Notice that the Mirror Status column changes to Verifying while the verification process occurs. When the verification is complete, Storage Mirroring will have created a log file for you to review. View the status of your verification process 5. Wait until your Mirror Status has returned to Idle and then open the file DTVerify.
Testing your target data At this point in your evaluation, you have completed a disaster recovery scenario. You may want to test your target data. The type of testing you will need to perform will depend on the type of data you are protecting. User data—If you are protecting user files, you can use the associated application to open the files on the target. Open one or more of the files to test the integrity of the data.
Configuring failover If you are interested in continuing your evaluation to test high availability, use the remaining instructions in this chapter to configure failover, simulate a failure, and perform failback and a restoration. 1. The Failover Control Center can be started from within the Management Console or from the Windows desktop. From the Management Console, select Tools, Failover Control Center. From the Windows desktop, select Start, Programs, Storage Mirroring, Failover Control Center.
Source machine and its IP addresses. Some of the failover settings are source specific and some can be set individually for each IP address on the source. Settings to configure the length of time before failover occurs Target machine information including the NIC which will assume the failover traffic, the monitoring method, and the IP addresses assigned to that NIC.
Simulating a failure To fully evaluate failover, you need to simulate a failure. The Failover Control Center does not have to be running in order for failover to occur, but for the purpose of this evaluation, make sure that it is running so that you can see each step of the process. 1. Ping the source’s IP address from a client machine. 2. Ping the source’s machine name from a client machine. 3. Disconnect the network cable(s) on the source.
Performing failback Failover occurred because the target was monitoring the source for a failure, and when a failure occurred, the target stood in for the source. User and application requests that were directed to the failed source are routed to the target. Failback is the process where the target releases the source identity it assumed during failover. As a result, user and application requests are no longer routed to the target, but back to the source.
Restoring your data If you are not using failover and your connection is for disaster recovery, the Management Console providesan easy method for restoring replicated data from the target back to the original source or to a new source server. You are only required to input the original source, the target, and the name of the replication set you want to restore. Storage Mirroring handles the rest, including selecting the files in the replication set and restoring them to the correct location. 1.
Conclusion After you have evaluated the benefits of powerful data protection software from HP, you can explore other ways to enhance and optimize your enterprise solution. Engage HP Sales and Training to help you realize your full potential. HP delivers a comprehensive portfolio of services that help you assess, design, plan, and implement effective data availability and disaster recovery solutions. These solutions help you avoid costly data loss and downtime.
