Selecting Backup Devices and Media


Many tools are available for backing up data. Some are fast and expensive. Others are slow but very reliable. The backup solution that's right for your organization depends on many factors, including

  • Capacity

    The amount of data that you need to back up on a routine basis. Can the backup hardware support the required load given your time and resource constraints?

  • Reliability

    The reliability of the backup hardware and media. Can you afford to sacrifice reliability to meet budget or time needs?

  • Extensibility

    The extensibility of the backup solution. Will this solution meet your needs as the organization grows?

  • Speed

    The speed with which data can be backed up and recovered. Can you afford to sacrifice speed to reduce costs?

  • Cost

    The cost of the backup solution. Does it fit into your budget?

Common Backup Solutions

Capacity, reliability, extensibility, speed, and cost are the issues driving your backup plan. If you understand how these issues affect your organization, you'll be on track to select an appropriate backup solution. Some of the most commonly used backup solutions include

  • Tape drives

    Tape drives are the most common backup devices. Tape drives use magnetic tape cartridges to store data. Magnetic tapes are relatively inexpensive but aren't highly reliable. Tapes can break or stretch. They can also lose information over time. The average capacity of tape cartridges ranges from 4 gigabytes (GB) to 10 GB. Compared with other backup solutions, tape drives are fairly slow. Still, the selling point is the low cost.

  • Digital audio tape (DAT) drives

    DAT drives are quickly replacing standard tape drives as the preferred backup devices. Many DAT formats are available. The most commonly used format is Digital Linear Tape (DLT) or Super DLT. With DLT IV, tapes have a capacity of either 35 GB or 40 GB uncompressed (70 GB or 80 GB compressed). Large organizations might want to look at Linear Tape Open (LTO) or Advanced Intelligent Tape (AIT) tape technologies. Typically, LTO tapes have a capacity of 100 GB uncompressed (200 GB compressed). With AIT-3, tapes have a capacity of 100 GB uncompressed (260 GB compressed).

  • Autoloader tape systems

    Autoloader tape systems use a magazine of tapes to create extended backup volumes capable of meeting the enterprise's high-capacity needs. With an autoloader system, tapes within the magazine are automatically changed as needed during the backup or recovery process. Most autoloader tape systems use DAT tapes formatted for DLT, LTO, or AIT. Typical DLT drives can record up to 45 GB per hour and you can improve that speed by purchasing a type library system with multiple drives. In this way you can record on multiple tapes simultaneously . In contrast, most LTO and AIT drives record over 100 GB per hour, and by using multiple drives in a system you can record hundreds of GB per hour .

  • Optical jukeboxes

    Optical jukeboxes are similar to autoloader tape systems. Jukeboxes use magnetic optical disks rather than DAT tapes to offer high-capacity solutions. These systems load and unload disks stored internally for backup and recovery operations. Their key drawback is the high cost.

  • Removable disks

    Removable disks, such as Iomega Jaz with 1 GB or 2 GB capacity, are increasingly being used as backup devices. Removable disks offer good speed and ease of use for a single drive or single system backup. However, the disk drives and the removable disks tend to be more expensive than standard tape or DAT drive solutions.

  • Disk drives

    Disk drives provide the fastest way to back up and restore files. With disk drives, you can often accomplish in minutes what takes a tape drive hours. So when business needs mandate a speedy recovery, nothing beats a disk drive. The drawbacks to disk drives, however, are relatively high costs compared to tape library systems.

Before you can use a backup device, you must install it. When you install backup devices other than standard tape and DAT drives, you need to tell the operating system about the controller card and drivers that the backup device uses. For detailed information on installing devices and drivers, see the section entitled "Managing Hardware Devices and Drivers" in Chapter 2 , "Managing Servers Running Microsoft Windows Server 2003."

Buying and Using Tapes

Selecting a backup device is an important step toward implementing a backup and recovery plan. But you also need to purchase the tapes or disks, or both, that will allow you to implement your plan. The number of tapes you need depends on how much data you'll be backing up, how often you'll be backing up the data, and how long you'll need to keep additional data sets.

The typical way to use backup tapes is to set up a rotation schedule whereby you rotate through two or more sets of tapes. The idea is that you can increase tape longevity by reducing tape usage and at the same time reduce the number of tapes you need to ensure that you have historic data on hand when necessary.

One of the most common tape rotation schedules is the 10-tape rotation. With this rotation schedule, you use 10 tapes divided into two sets of 5 (one for each weekday). The first set of tapes is used one week and the second set of tapes is used the next week. On Fridays, full backups are scheduled. On Mondays through Thursdays, incremental backups are scheduled. If you add a third set of tapes, you can rotate one of the tape sets to an off-site storage location on a weekly basis.

The 10-tape rotation schedule is designed for the 9 to 5 workers of the world. If you're in a 24 x 7 environment, you'll definitely want extra tapes for Saturday and Sunday. In this case, use a 14-tape rotation with two sets of 7 tapes. On Sundays, schedule full backups. On Mondays through Saturdays, schedule incremental backups.



Microsoft Windows Server 2003 Administrator[ap]s Pocket Consultant
Microsoft Windows Server 2003 Administrator[ap]s Pocket Consultant
ISBN: 735622450
EAN: N/A
Year: 2003
Pages: 141

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