Selecting the Right Backup Medium and Hardware for Your Exchange Server Deployment

Exchange 2000 Server Release Candidate 1 (RC1) has left the building. That’s right. Last Friday at approximately noon, Microsoft signed off on and sent RC1 to enterprise accounts that are participating in the Exchange Early Adopter Program. If you've been waiting for feature-complete code and the performance tuning that goes into the late stages of a software development project of this magnitude, Exchange 2000 RC1 is for you. For my team, as well as early adopters of Exchange 2000, RC1 represents a point where we can begin serious testing efforts with the confidence that the code is relatively stable. I look forward to installing RC1 for my current project (Exchange 2000 clusters) and beginning my testing in earnest.

Last week, we discussed some of the features to look for when selecting backup software for your Exchange Server deployments. The discussion is not complete without addressing backup hardware selection. In addition to selecting the backup software technology that best meets your organization's needs, you need to put careful thought into the hardware technology choice to which you will marry that software. You have many media options for storing critical backup sets required to recover your Exchange servers. Quarter Inch Cartridge (QIC), Digital Audio Tape (DAT), and Digital Linear Tape (DLT) are among the most popular media choices, and each type has advantages and disadvantages that you need to consider when selecting an appropriate backup medium (and therefore your hardware device). In addition, each option will have a different cost point that you must justify. In some cases, the device and media might be relatively inexpensive but come at some cost in terms of reliability. In other cases, the most reliable option might also be the most expensive. You need to weigh all the technological, reliability, and cost factors against your organization's disaster recovery requirements. The important factors to consider when selecting backup hardware include vendor support, configuration flexibility (e.g., RAID support, parallel streaming, automation), capacity (1GB to 70GB), error detection and correction, cleaning-duty cycle, head and tape life, compression, and cost.

I've always preferred DLT drives and array technology to DAT or QIC devices and media (a bias from the VAX era of TK50 and TK70 tapes). DLT technology is more expensive, but it offers superior capacity, reliability, performance, and drive and tape life compared to QIC or DAT options. DLT technology also offers more configuration flexibility. You can use DLT drives standalone as individual drives or configured in RAID arrays for increased performance, capacity, and reliability. Although QIC and DAT might be less expensive and thus more feasible for smaller Exchange deployments and organizations, these technologies cannot match the strengths of DLT technology.