Windows Small Business Server 2011 : Creating a Backup Strategy

In addition to the standard hard disk drive unit, identical to the ones you install inside your computers, an external hard disk consists only of a case, a power supply, and an interface to your computer. You can remove the hard disk from the case and install it in a computer if you want to. You can also purchase an empty external drive housing and install a hard disk drive you already own into it. External hard disk drives make excellent backup solutions. They are inexpensive, fast, hold a lot of data, and disconnect easily from the computer.

External hard drives have been available for many years, but until recently, they were Small Computer System Interface (SCSI) drives that required a special host adapter in the computer and an expensive cable. Today, there are three external interfaces that are suitably fast for hard disk connections. They are listed in Table 1.

Virtually all the PCs on the market today include USB ports, and many have some combination of eSATA and IEEE 1394 ports as well. Computers with ports on the front of the case are particularly attractive for backup devices, so that you can remove them easily. All these interfaces support hot swapping, which enables you to attach and detach devices without powering down the computer.

Nearly all the external hard drives on the market support USB, and most have at least one additional interface, such as eSATA, IEEE 1394b, or IEEE 1394a. Some products include support for all of the interfaces. Most external hard drive products use Serial AT Attachment (SATA) hard drives, with a bridge circuit that enables them to connect to a USB or IEEE 1394 interface. The eSATA interface eliminates the need for the bridge, which can enable certain advanced drive technologies to function as in an internal installation, and provides a far faster transfer rate. Cable length for eSATA devices is limited to 2 meters, however.

Although the USB 2.0 specification indicates a better level of performance than IEEE 1394a, IEEE 1394a devices tend to outperform USB 2.0 ones in real-world implementations, but only marginally. IEEE 1394b is decidedly faster than USB 2.0, but eSATA can provide substantially better performance than either. However, USB 2.0 and IEEE 1394a are both adequate backup solutions for most situations. If your server has an integrated eSATA port, you would be well to use it, but unless you have a need for the fastest possible interface, an integrated USB or IEEE 1394 connection is likely to be a more reliable and economical solution than an after-market eSATA card.

Most external hard drives have their own power supplies, but there are a few models that draw power from the USB or IEEE 1394 interface. These latter devices are generally designed as portable solutions for notebook computers. For server backups, an independent power supply is preferable. Apart from these factors, the only other specifications to consider are those of the hard drive itself. More RPMs and a larger cache are certainly preferable for a backup solution, but they can add to the cost of the unit.

Magnetic tape has long been the industry standard backup medium. Tape capacities and transfer speeds have kept pace with hard disk characteristics over the years; they can store data for years, and the media cost per gigabyte of storage is relatively low. With magnetic tape, because the storage medium is separate from the drive mechanism, there is far less that can go wrong. If you drop a tape cartridge on the floor, it is probably still usable; not so with a hard disk drive, in many cases.

Magnetic tape drives are different from the other types of storage media that computers use, in that they are not random access devices. You cannot immediately access any file on a tape by moving the drive heads to a specific location or by accessing a specific memory address, as you can with other media. With magnetic tape, the drive must spool through the reel of tape until it locates the desired file, a process that can take several minutes.

Because of this, you cannot use a magnetic tape drive for anything other than backups. You can’t mount a tape as a volume and assign it a drive letter, as you can with other media. Instead, computers use a special software driver to address the tape drive and send data to it. When you purchase a backup software product that supports magnetic tape, you must make sure that it supports the specific magnetic tape drive you plan to use.

There are a variety of magnetic tape drive technologies available, with varying tape capacities, transfer speeds, and prices. At one time, there were relatively low-cost tape systems on the market, intended for backups of standalone computers and small networks. However, they have been made almost entirely obsolete by writable optical disks, flash drives, and external hard drives. Today, the magnetic tape drive market is concentrated on high-end network backup solutions, using technologies such as Digital Linear Tape (DLT), Linear Tape-Open (LTO) Ultrium, Advanced Intelligent Tape (AIT), and Digital Data Storage/Digital Audio Tape (DDS/DAT).

In addition, complex hardware devices called autoloaders can be as large as household refrigerators and house multiple tape drives and dozens of tape cartridges. These devices can provide fully automated backup solutions for enormous amounts of data.

The question then is whether a modest magnetic tape solution is suitable for a small business network. In most cases, the answer is no. The combination of a magnetic tape drive and its required software provide far more capability than Windows Server Backup and an external hard drive, but with prices that start at US $1,000 and climb steeply into the stratosphere, most small business owners find the cost to be prohibitive.

As mentioned earlier, one of the requirements for full backup protection is a removable storage medium that you can take offsite to protect against fire, theft, and other disasters. If you use magnetic tape, this is easy. Most tape backup software packages implement a tape rotation scheme that makes copies of your data to store offsite.

With external hard drives, storing data offsite means removing the entire device, not just the storage medium. Fortunately, the devices are not so expensive that it is impractical to purchase more than one, and Windows Server Backup provides the ability to perform simultaneous backups to multiple devices. Therefore, if you plan to use external hard drives for your backup medium, you should purchase at least two, so that you can create two copies of your data and store one offsite. For organizations that require a permanent archive of their data, you might want to purchase a new backup drive each month, perform an additional backup job, and store those monthly drives offsite.

Online backup—sometimes called remote backup or managed backup—is a third-party service that enables an organization to back up its data to a remote site over the Internet. These services typically can provide many or all of the same features as a high-end backup software product, with the additional advantage that the consumer is not responsible for the purchase and maintenance of the backup hardware.

Online backup services provide many additional advantages over onsite solutions, including the following:

There are potential disadvantages to online backup solutions as well, including the following:

Online backup can provide any service that a standalone backup software package can. The customer typically configures the backup jobs using a website interface that functions very much like the application supplied with a backup software product.