Upgrading and Repairing PCs

Tape Drives

The data backup and archive needs of a personal computer can be overwhelming. People with large hard drives and numerous applications installed and those who generate a large amount of data might need to back up their computers on a weekly or even a daily basis.

In addition, a critical need on today's PCs is data storage space. Sometimes it seems as though the storage requirements of a PC can never be satisfied. On nearly any PC used for business, study, or even fun, the amount of software installed can quickly overwhelm even a large hard drive. To save space on the primary storage devices, you can archive infrequently used data to another storage medium. Depending on the method you use for archiving data to secondary storage, you might be able to read the data directly from the device, or you might need to restore the data to the drive before you can access it. If you copy data to the drive with drag-and-drop, the data can be read from the media directly. However, if you use a backup program to create the backup, you will need to use that same program to access the data and restore it to a drive before it can be reused.

Historically, a popular method for backing up full hard disks or modified files has been a tape backup drive. This section focuses on current tape backup drive technologies to help you determine whether this type of storage technology is right for you.

Tape backup drives are the most simple and efficient device for creating a full backup of your hard disk if the tape is large enough. With a tape backup drive installed in your computer, you insert a tape into the drive, start your backup software, and select the drive and files you want to back up. The backup software copies your selected files onto the tape while you attend to other business. Later, when you need to retrieve some or all of the files on the backup tape, you insert the tape in the drive, start your backup program, and select the files you want to restore. The tape backup drive takes care of the rest of the job.

This section examines the various types of tape backup drives on the market, describing the capacities of different drives as well as the system requirements for installation and use of a tape drive. The following topics are covered in this section:

• Hard-disk-based alternatives to tape backup

• Advantages and disadvantages to tape backup

• Common standards for tape backup drives

• Common backup tape capacities

• Newer higher-capacity tape drives

• Common tape drive interfaces

• Portable tape drives

• Tape backup software

Hard-Disk-Based Alternatives to Tape Backup

Before you decide to adopt a tape backup as your backup strategy, keep the following alternatives in mind:

• External hard drives. Maxtor, Western Digital, SimpleTech, and others have developed external hard drives with capacities ranging from 20GB up to 200GB. These drives attach through USB 1.1, USB 2.0, or IEEE-1394a ports and can be used for data backup with backup software or drag-and-drop file copying. The Maxtor Personal Storage 5000 family has an exclusive OneTouch feature that starts the file copying process automatically and can be used to launch Dantz Retrospect Express backup software.

• RAID arrays. By connecting identical hard disks to a RAID array using RAID 1 data mirroring or RAID 5 data striping with parity, your data is automatically backed up as soon as it is created. RAID arrays were once used strictly for SCSI drives on networks because of their high cost. However, recent developments in high-performance, low-cost, RAID 1-compatible ATA host adapters on motherboards and add-on cards make this another useful backup strategy to consider. RAID 5 arrays generally require a separate host adapter.

Disadvantages of Tape Backup Drives

Many computer users who once used tape backups for data backup purposes have turned to other technologies for the following reasons:

• Creating a tape backup copy of files or of a drive requires the use of a special backup program in almost all cases. A few tape drives allow drive letter access to at least part of the tape capacity, but this feature is far from universal.

• Retrieving data from most tape backup drives requires that the data files be restored to the hard disk. Other types of backup storage can be treated as a drive letter for direct use from the media.

• Tape backups store and retrieve data sequentially. The last file backed up can't be accessed until the rest of the tape is read; other types of backup storage use random access, which enables any file on the device to be located and used in mere seconds.

• Low-cost tape backups using QIC (Quarter Inch Committee), QIC-Wide, or Travan technology once had little problem keeping up with increases in hard disk capacity and once sold for prices comparable to or less than the hard disks they protected. Today's hard disks have capacities of 20GB–200GB and are far less expensive than most comparably sized tape backups. As a result, more expensive, higher-capacity tape drives are needed to achieve single-cartridge backups.

• Newer backup and restore techniques, such as drive imaging/ghosting, rival the ease of use of tape backups and permit data restoration with lower-cost optical storage devices such as CD-RW or rewritable DVD drives. These alternatives are particularly useful if only a few GB of data needs to be backed up on a continuing basis.

For these reasons, the once-unassailable position of a tape backup drive as being the must-have data protection accessory is no longer a secure one; plenty of rivals to tape backups are on the market. However, if you can afford a high-quality DDS or AIT tape drive, you can get a high-performance and high-reliability solution because these same drives are used in the demanding roles of network backup.

Advantages to Tape Backup Drives

Although tape backup drives are no longer the one-size-fits-all panacea for all types of bigger-than-floppy storage problems, they have their place in keeping your data safe. Following are several good reasons for using tape backup drives:

• Tape backups are a true one-cartridge backup process for individual client PCs, standalone computers, or network servers when high-capacity tape drives and cartridges are used. Anytime multiple tapes or disks must be used to make a backup, the chances of backup failure increase.

• If you or your company has made previous backup tapes, you must keep a tape drive to access that data or perform a restore from it. Tape backup drives are necessary if you need to restore from previously made backup tapes.

• If you want an easy media rotation method for preserving multiple full-system backups, tape backup drives are a good choice.

In general, tape drives are used where high capacity and high reliability are paramount. They can be expensive initially but are extremely inexpensive when you factor in the low cost of the media over time.

Common Tape Backup Standards

Tape drives come in a variety of industry-standard as well as some proprietary formats. The following list details several of the available formats:

• QIC, QIC-Wide, and Travan. Travan is a development of the QIC and QIC-Wide family of low-cost, entry-level tape backup drives. Travan drives can handle data up to 40GB at 2:1 compression.

• DAT (Digital Audio Tape). This is a newer technology than QIC and its offshoots, and it uses Digital Data Storage (DDS) technology to store data up to 40GB at 2:1 compression (DDS-4) and up to 72GB in the new DDS fifth-generation drives. DAT drives are often referred to as DDS drives for this reason.

• AIT (Advanced Intelligent Tape). This is becoming the successor to DAT/DDS because it can handle higher capacities than DAT.

• OnStream's ADR (Advanced Digital Recording) and ADR². This features a capacity up to 50GB at 2:1 compression and a choice of SCSI, ATA, and popular external interfaces in its 30GB and 50GB (2:1 compression) versions for desktop computers. ADR² has compressed capabilities up to 120GB (2:1 compression).

• Exabyte (formerly Ecrix)'s VXA-1 and VXA-2 drives. VXA-1 offers a capacity of 66GB at 2:1 compression and a variety of high-speed SCSI and IEEE-1394 interface options. The VXA-1 format has been approved by the ECMA, an important international organization that establishes standards for information and communication systems. The improved VXA-2 drives have capacities up to 160GB (2:1 compression).

Other tape backup standards, such as DLT (Digital Linear Tape) and 8mm, are used primarily with larger network file servers and are beyond the scope of this book.

QIC and Its Variants (QIC-Wide and Travan)

The first 1/4'' tape drive was introduced in 1972 by 3M, and it used a cartridge size of 6''x4''x5/8''. This pioneering cartridge established the so-called "DC" data cartridge standard that was used with the first true QIC-standard drive—the 60MB QIC-02, introduced in 1983–1984. The QIC-02-compatible drives were sold for several years and, like many early tape backup drives, used a dedicated host adapter board. QIC-02's small capacity began to be a problem in the mid-1980s, and many other QIC standards were created for larger drives.

The QIC (http://www.qic.org) has introduced more than 120 standards over the years in both the older DC and newer minicartridge (MC) forms. This huge number of standards has actually led to a fragmented marketplace that makes it increasingly difficult to determine the backward-compatibility and cross-compatibility factors that QIC, ironically, was established to provide. QIC-Wide technology, developed by Sony, is not an official QIC standard, but QIC-Wide drives can read and write some types of QIC minicartridge media.

This section focuses on the recent and current minicartridge versions of Travan, the latest development of the QIC and QIC-Wide standards.

Note For more information on QIC and QIC-Wide standards, see Chapter 12 of Upgrading and Repairing PCs, 11th Edition, and Chapter 12 of Upgrading and Repairing PCs, 12th Edition, found in their entirety on the DVD-ROM accompanying this book.

Travan Cartridge Tape

The successor to both QIC-MC and QIC-Wide drives was created in 1994 by 3M (now Imation). Travan drives maintain backward compatibility with various QIC standards and provide backup capabilities up to 20GB uncompressed and 40GB at 2:1 compression.

The Travan platform features a unique drive/minicartridge interface patented by Imation. The Travan platform fits in a 3 1/2'' form factor, enabling easy installation in a variety of systems and enclosures. Travan drives can accept current QIC, QIC-Wide, and Travan minicartridges—a critical need for users, given the installed base of more than 200 million QIC-compatible minicartridges worldwide.

Currently, several levels of Travan cartridges and drives are available, each based on a particular QIC standard. Table 12.4 lists the standard Travan cartridges and capacities. All Travan cartridges use .315'' (8mm) wide tape.

Table 12.4. Travan Family Cartridges and Capacities

Travan Cartridge (Previous Name)	Capacity/2:1 Compression	Read/Write Compatible with	Read Compatible with
Travan-1 (TR-1)	400MB/800MB	QIC-80, QW5122	QIC-40
Travan-3 (TR-3)	1.6GB/3.2GB	TR-2, QIC-3020, QIC-3010, QW-3020XLW, QW-3010XLW	QIC-80, QW-5122, TR-1
Travan 8GB (Travan 4/TR-4)	4GB/8GB	Travan 8, QIC-3080, QIC-Wide (3080)	QIC-80, QIC-3010, QIC-Wide (3010), QIC-3020, QIC-Wide (3020), TR-1, TR-3
Travan NS-8[1]	4GB/8GB	TR-4, QIC-3080	QIC-Wide (3080)
Travan NS-20 (Travan TR-5)	10GB/20GB		Travan 8GB, QIC-3095
Travan 40GB (Travan TR-7)	20GB/40GB		Travan NS-20

^[1] This cartridge can be used in place of the Travan 8GB (TR-4); the same cartridge can be used on either NS8 or TR-4 drives.

Note Backward compatibility can vary with drive; consult the manufacturer before purchasing any drive to verify backward-compatibility issues.

Most Travan drives on the market today use the Network Series (NS) technology described in the following section.

The Travan NS

Drives that support Travan NS technology are designed to solve two problems that have plagued tape backup users for many years: data compression and data verification.

On QIC-40 and above, QIC-Wide, and standard Travan drives, data compression is performed by the backup software used by the drive. This could cause the following problems:

• Drives might have difficulty reading data if different backup software was used to make the backup and perform the restoration.

• The speed of the computer had a major impact on how fast backups could be performed; a typical backup program (such as Iomega's Ditto Tools) would offer three settings—no compression, compress to save time, and compress to save space—forcing the user to choose between maximum data storage and maximum speed.

On the same drives, backup software supports a verification step that compares the data written to the tape with the data on the drive. Unfortunately, this requires that the tape be rewound to the beginning of the current backup and be read to the end while the hard disk is also read. The result? A backup that took 45 minutes without verification would take more than 90 minutes with verification enabled. This inefficient write-rewind-reread process has discouraged many users from relying on this safer backup method. Also, errors caused by changes in the state of a Windows 9x computer (such as screensavers being enabled or swapfiles changing in size) during the time passage between backup and verify tended to create the erroneous notion that the backup wasn't accurate.

Travan NS–compatible drives (including the Travan 40) use a dual-head design, shown in Figure 12.8, that enables data to be verified as soon as it is written (read-while-write). They also feature hardware data compression, which allows a higher data capacity (up to 40GB at 2:1 compression). The result is faster and more reliable backups. The Travan NS20 and Travan 40 cartridges also use a different metal media formula for greater data density than older Travan drives do.

Currently, Travan NS20 and Travan 40–based drives are sold primarily by Seagate Removable Storage Solutions LLC (Seagate RSS).

Proprietary Versions of Travan Technology

Ironically, because Travan technology was designed to bring an end to the QIC MC—QIC-Wide tape "wars," some drives use proprietary versions of the Travan standard. Nonstandard sizes include

• 5GB Tecmar/Iomega DittoMax^[1]

  ^[1] Iomega sold the Ditto and DittoMax backup product line to Tecmar, which went out of business in 2002. Although media is still available for these drives from Imation, they are orphans without technical support and should be replaced.

• 5GB HP/Colorado

• 6.6GB AIWA Bolt^[2]

  ^[2] AIWA Computer Systems Division was shut down in October 1999. These are orphan drives that should be replaced.

• 7GB Tecmar/Iomega DittoMax^[1]

• 10GB Tecmar DittoMax^[1]

• 14GB HP/Colorado

The drive manufacturer is the principal supplier of media for some of these drives, whereas others are also supported with third-party media. Consult the drive manufacturers' Web sites for details.

OnStream ADR Technology

Introduced in 1999, OnStream's ADR (advanced digital recording) technology tape drives are designed to answer many of the limitations of and complaints users have had about traditional tape backup solutions.

OnStream was founded in February 1998, as a spin-off from Philips Electronics. Its CEO, William T. Beierwaltes, had previously founded low-cost backup leader Colorado Memory Systems (now the HP/Colorado division of Hewlett-Packard).

Although the future of OnStream was uncertain after the liquidation of OnStream's U.S. operations (OnStream, Inc.) in March 2001, a new company—OnStream Data B.V.—based in the Netherlands immediately took over sales, support, and development of OnStream drives and technology. The U.S. operations of the new OnStream Data company are located in Austin, Texas. OnStream-compatible ADR tape cartridges are available from Verbatim in both 30GB and 50GB capacities, as well as from OnStream Data. ADR² tape cartridges for 60GB–120GB (compressed) ADR² drives are sold exclusively by OnStream Data.

Features of ADR and ADR²

ADR uses a multiple-track linear recording system that reads and writes eight tracks at once, enabling read-while-write verify for speed and reliability and a relatively low tape travel speed to minimize wear (and noise!). ADR also uses several other techniques to foster additional reliability:

• Embedded servo information keeps the read/write heads aligned with the tracks at all times.

• ECC (error correction code) recording applied over all eight tracks (spatially distributed) allows reliable data recovery even if an entire track is destroyed.

• Continuously variable tape travel speeds enable the drive to adjust to the different speeds of data flow from the hard drive without slowing down the entire tape backup process; as the data transfer rate increases, the drive runs faster, and the drive slows down as the data transfer rate decreases.

• Single-pass media defect mapping allows reliable recording without rewinding the tape for a separate verify pass.

The second-generation ADR² adds the following features:

• Half the track width, allowing twice the data on the same length of tape

• Enhanced servo system

• Reinforced actuator mounting plate (RAM plate) mounting for head assembly on high-speed SCSI drives for improved read/write performance and accuracy

• Adaptive temperature compensation (ATC) to improve recording quality

• Mid-load point tape positioning to cut access times in half

User Benefits of ADR

Several benefits to ADR are as follows:

• ADR drives can be treated as a drive letter when used with the included Echo software. This includes drag-and-drop file transfer and direct use of the tape's contents without a restore step (including viewing full-motion video and listening to MP3s).

• Quiet backups. These result from the multiple-track recording feature and variable-speed motor.

• Background "set it and forget it" backup operation at reduced speed or fast dedicated backup of large hard drives in just an hour or two.

• Low cost perMB for both drives and media.

• Reliable data backup and online storage in a single device. The claimed reliability for ADR technology media exceeds the reliability of both other tape backup systems and hard drives.

ADR and ADR² Technical Specifications

Table 12.5 lists the technical specifications for OnStream's line of ADR drives, available in ATA, various flavors of SCSI, parallel, and USB interfaces. Drives for Macintosh only and drives bundled with third-party backup programs are also available but are not listed. All drives listed are supplied with OnStream's Echo software. Table 12.6 lists the technical specifications for ADR² drives, available in ATA, SCSI, and USB 2.0. ADR² drives are packaged with Yosemite TapeWare XE software.

Media retail is $40 for the 30GB ADR cartridge in a single pack and $60 for the 50GB ADR cartridge in a single pack. ADR² media retails for about $65 for the 60GB cartridge and about $95 for the 120GB cartridge. Multiple-cartridge packs are available at a reduced price. All capacities listed for media and drives assume a 2:1 compression ratio.

OnStream is the only producer of ADR drives at this writing. The ADR recording process is illustrated in Figure 12.9 (as compared to the DAT helical recording process).

Table 12.5. OnStream ADR Family Specifications for Windows PCs

Drive Model	Interface	Performance	Retail	Media Used
DI30	ATAPI	1–2MBps	$299	ADR 30GB
DP30	Parallel	.7–1.4MBps	$399	ADR 30GB
USB30	USB	.85–1.7MBps	$399	ADR 30GB
SC30	SCSI internal	2–4MBps	$499	ADR 30GB
SC30	SCSI external	2–4MBps	$599	ADR 30GB
SC50	SCSI internal	2–4MBps	$699	ADR 50GB or 30GB
ADR50 Int	LVD SCSI internal	4–8MBps	$799	ADR 50GB or 30GB
ADR50 Ext	LVD SCSI external	4–8MBps	$949	ADR 50GB or 30GB

OnStream Data also makes an external IEEE-1394 version of its 30GB (2:1 compression) drive but offers it only for the Macintosh platform.

Table 12.6. OnStream ADR² Family Specifications for Windows PCs

Drive Model	Interface	Performance	Retail	Media Used
ADR2.60IDE	ATAPI	2.5–5MBps	$500	ADR2 60GB
ADR2.60usb	USB 2.0	2.5–5MBps	$729	ADR2 60GB
ADR2.60si	SCSI WideUltra2 int.	4–8MBps	$749	ADR2 60GB
ADR2.60se	SCSI WideUltra2 ext.	4–8MBps	$889	ADR2 60GB
ADR2.120si	SCSI WideUltra2 int.	4–8MBps	$999	ADR2 120GB,60GB
ADR2.120se	SCSI WideUltra2 ext.	4–8MBps	$1,149	ADR2 120GB,60GB
ADR2.240sr[*]	SCSI WideUltra2 rackmt.	8–16MBps	$1,799	ADR2 120GB,60GB

^[*] This model contains two 120GB ADR2.60 tape drives.

DAT/DDS, AIT, and Other High-Capacity Tape Drive Standards

Although Travan capacities have now reached 40GB compressed, users of today's high-capacity hard drives must turn to larger tape backup standards. In addition to the OnStream ADR, the same tape backup standards long supported by workstation and large network servers can also be used with today's versions of Windows for both individual desktop computers and small network servers. Additionally, new high-capacity technologies are available to support today's larger drives.

4mm digital audio tape (DAT/DSS), 8mm videotape, 8mm AIT, digital linear tape, scalable linear recording (SLR), and Ecrix VXA are the major choices available for users who need higher-capacity backups. An emerging choice for very high-capacity (100GB and up) drives is the Ultrium version of the LTO Technology standard. All these technologies are available in autoloading tape libraries suitable for large networks, as well as single-cartridge drives intended for small network servers or desktop use.

Proprietary Versus Open Standards

If you want a wider variety of choices in drives, media, and pricing, you might prefer to purchase a high-performance drive type that is made by several companies. However, some of the most advanced technologies are controlled by a single vendor.

Drive technologies available from multiple vendors include

• DAT/DDS. Introduced and licensed by Sony to numerous manufacturers. Fifth-generation DDS drives are sold by HP and Seagate RSS.

• AIT. Introduced and licensed by Sony to numerous manufacturers.

• DLT. Originally developed by Digital Equipment Corporation, but was purchased by Quantum in 1994.

• LTO (Linear Tape-Open). Developed by HP, IBM, and Seagate RSS.

The following drive technologies are sold by a single vendor:

• SLR. Tandberg Data

• VXA. Exabyte-Ecrix

However, third-party vendors might sell tape cartridges compatible with even so-called "proprietary" standards.

DAT/DDS Tape Drives

Of the many high-performance tape drives on the market, this author's longtime favorite has been the DAT/DDS tape drive family because of its combination of performance, capacity, reliability, and reasonable price. Four levels of DAT/DDS drive capacity are available:

• DDS-1. This entry-level member of the family (2GB native/4GB at 2:1 compression) is now obsolete.

• DDS-2. Has the same capacity as drives based on Travan NS8 (4GB native/8GB at 2:1 compression).

• DDS-3. Has a slightly larger capacity (12GB native/24GB at 2:1 compression) than Travan NS20.

• DDS-4. Has a 20GB native/40GB at 2:1 compression capacity, which is double the capacity of Travan NS20 and equal to Travan 40GB.

• DDS Fifth Generation. The newest member of the DAT/DDS family, it has a 36GB native/72GB at 2:1 compression capacity.

Even though DAT/DDS drives are more expensive than Travan drives with similar capacities, the media cost is much lower because of the drive's design. For example, you will pay about three times as much for a Travan NS20 cartridge as for a slightly higher-capacity DDS-3 cartridge. A DDS-4 cartridge, which offers double the capacity of Travan NS20, still sells for about 30% less. DDS drives are more reliable than Travan or earlier QIC-based drives, which is a vital consideration because the most important reason to use a tape backup is to perform a restore. The enhanced reliability of DDS drives is aided by the inclusion of automatic head-cleaning features built into most DDS drives and media.

After Sony announced in April 2001 that DDS-4 tape drives would be the end of the DAT/DDS lineup of drives, the future of DAT/DDS tapes was uncertain. However, in January 2003, HP and Seagate RSS announced the development of a fifth generation of DDS drives with higher capacity and backward read/write compatibility. This new format nearly doubles the capacity of DDS-4 and adds several improvements in reliability as well.

Helical Scan Recording on DAT, 8mm, and AIT Drives

Exabyte 8mm, Sony DAT/DDS, and Sony AIT use helical scan recording. The read/write heads used in helical scan recording are mounted on a drum and write data at a slight angle to the tape, using a mechanism highly reminiscent of that in a VCR (refer to Figure 12.9). The entire surface of the tape is used to store data, enabling more data to be placed in a given length of tape than with the linear recording techniques used by the QIC family of drives.

AIT Unique Features

Sony's AIT has several unique features designed to make backup and restoration faster and more reliable. An optional Memory In Cassette (MIC) chip allows the cartridge to remember which of the 256 on-tape partitions were used for the data you want to restore, so the correct starting point can be located in seconds. AIT drives also have a servo tracking system called Auto Tracking Following (ATF), which is used for accurate data-track writing, and Advanced Lossless Data Compression (ALDC), a mainframe-style compression method that can compress data to a greater extent than other methods. The drives have several other features, including built-in head cleaning that is activated when soft (correctable) errors reach a preset limit, metal-evaporated tape media that avoids head contamination, and a 3 1/2'' form factor.

DLT Unique Features

DLT segments the tape into parallel horizontal tracks and records data by streaming the tape across a single stationary head at 100''–150'' per second during read/write operations. This is a dramatic contrast to traditional helical-scan technology, in which the data is recorded in diagonal stripes with a rotating drumhead while a much slower tape motor draws the media past the recording head.

The result is a very durable drive and a robust medium. DLT drive heads have a minimum life expectancy of 15,000 hours under worst-case temperature and humidity conditions, and the tapes have a life expectancy of 500,000 passes.

SLR Unique Features

Tandberg's SLR drives use a linear recording method; the tape used by the SLR 40, SLR 60, and SLR 100 is divided into 192 tracks. Twenty-four prewritten servo tracks are used to adjust the position of the read/write head as necessary. This feature is designed to ensure compatibility of SLR tapes between drives, enabling a tape written by one drive unit to be readable by another unit. Six tracks are written at the same time. The entry-level SLR7 uses a simplified recording method that uses two tracks. Both tape types have fault-tolerance features that enable the drive to switch to another track for data recording if the original track fails. SLR media is available from most major tape vendors.

Exabyte VXA Unique Features

The Exabyte VXA drives (originally developed by Ecrix, which merged with Exabyte in November 2001) combine special recording and playback methods. The recording method used somewhat resembles a normal helical scan, but the tape is guided past the magnetic drum with a completely different type of mechanism and the data is recorded at variable speeds that change according to how fast the host can transmit data. This eliminates the need to wind tape backward because of data underruns (back-hitching). Data is recorded in 64-byte groups of 387 data packets rather than in linear blocks. VXA drives use a special read feature called overscan operation (OSO). OSO performs redundant reads of each group of data packets, enabling data to be retrievable even from damaged tapes. The packetizing of data works the same way as on the Internet: Data can be read in any order and reassembled into its original form when all packets are received. In tests, Exabyte and Ecrix have boiled, frozen, and even poured hot coffee over VXA tapes and been able to retrieve 100% of the stored data.

LTO Technology Unique Features

Linear Tape-Open, better known as LTO, is a very high-performance tape backup technology that offers two distinct types of mechanisms:

• Ultrium. This implementation of LTO is optimized for very high capacities. For example, Ultrium drives have an uncompressed capacity of 100GB (200GB at 2:1 compression) and transfer rates of 20MBps–40MBps. Ultrium Generation 2 drives have an uncompressed capacity of 200GB (400GB at 2:1 compression) and transfer rates of 40MBps–80MBps. Both types of drives also have special features such as dynamic power-down (protects tapes from damage during a power interruption), intelligent data compression, intelligent media analysis to avoid suspect tape areas, and variable tape speed to minimize back-hitching (moving the tape backward because of a data underrun). Ultrium drives are popular in both single-drive and tape-library formats, although they are quite expensive: Basic single-cartridge units start at around $3,500, with 100GB (uncompressed) cartridges selling for about $80–$90 each.

• Accelis. This proposed implementation of LTO is optimized for very high speeds, using a dual-reel cartridge that enables tape to be loaded from the mid-point instead of the beginning. It has a native capacity of 25GB (50GB at 2:1 compression) and features cartridge memory (used to retrieve data about the cartridge's previous use to make locating data faster) and throughput of 20MB–40MB per second. Because Ultrium drives achieve the same speeds at much higher capacities, it's no surprise that Accelis appears to be an on-paper variation at this point, with no drives on the market using this variation on LTO.

Comparing Tape Backup Technologies

As the preceding sections indicate, you have many choices in large, high-performance tape backup. All the drive technologies discussed in this section use various SCSI interface versions and can be purchased as internal or external drives; some are also available with USB 2.0 or IEEE-1394a interfaces. Even though they are more expensive than Travan or OnStream ADR drives, they offer the capacities needed by today's larger hard drives.

Unlike the confusing backward-compatibility picture for QIC-family drives, the more advanced drives in each family are backward compatible with smaller drives.

Table 12.7 summarizes the performance and other characteristics of these tape technologies and compares them to Travan NS20 and 40GB drives and OnStream ADR and ADR² drives. The prices of the tape drives vary tremendously depending on which version of SCSI is selected, whether the drive is internal or external, and whether a single-tape or tape-library drive is selected. The standards shown in Table 12.7 are listed in order by native capacity. All drive interfaces are SCSI, except as noted. Maximum prices listed are for the most expensive single-drive SCSI interface model except as noted; most models of a given drive will be cheaper, depending on the SCSI version supported, whether the drive is sold bare or as a kit, and whether it is internal (less expensive) or external.

Table 12.7. High-Performance Tape Backup Standards Compared

Drive Type	Capacity/2:1 Compressed	Backup Speed (Native/Compressed)	Drive Price Range	Media Cost
Travan NS20	10GB/20GB	1–2MBps	under $400	under $40
DAT DDS-3	12GB/24GB	1.1–2.2MBps	around $600	around $13
ADR 30GB	15GB/30GB	1–2MBps ATA 2–4MBps SCSI	under $300 under $600	around $40
Travan 40GB	20GB/40GB	2–4MBps ATA 1–2MBps USB 2	around $400 around $430	around $45 around $45
DAT DDS-4	20GB/40GB	2–4.8MBps	under $1,500	under $40
Exabyte 8mm (Mammoth)	20GB/40GB	3–6MBps	under $2,700	around $60
SLR7	20GB/40GB	3–6MBps	under $1,000	around $50
DLT 4000	20GB/40GB	1.5–3MBps	under $2,000	around $70
SLR50	25GB/50GB	2–4MBps	around $2,100	around $75
ADR 50GB	25GB/50GB	2–4MBps SCSI 4–8MBps LVD SCSI	around $650	around $50
ADR2 60GB	30GB/60GB	4–8MBps	around $750	around $65
SLR60	30GB/60GB		around $960	around $65
VXA-1	33GB/66GB	3–6MBps	under $1,200	around $80 (33/66GB); around $50 (20/40GB); around $30 (12/24GB)
AIT-1	35GB/70GB	3–6MBps	under $1,000	around $65
DLT 8000	40GB/80GB	3–6MBps	under $1,400	around $60
SLR100	50GB/100GB	5–10MBps	around $1,500	around $75
AIT-2	50GB/100GB	6–12MBps	under $1,400	around $80
ADR2 120GB	60GB/120GB	4–8MBps	about $1,000	around $90
VXA-2	80GB/160GB	6–12MBps	around $1,000	around $100

From Table 12.7, you can see that the Travan NS20 drives are among the least expensive SCSI-based drives to purchase, but the cost per MB for media is much lower with DAT/DDS drives. The performance is higher with all 20GB and up drives of other types. For an individual computer or small network server, the ADR50, ADR², DDS-3, DDS-4, SLR7, VXA-1, and VXA-2 drive families represent the best balance of initial cost, performance, and media cost per MB. DLT, Exabyte 8mm, and AIT drives are better choices for larger network server backup, especially if purchased in their more expensive tape-library forms (not listed).

Note To learn more about DAT, DLT, and Exabyte 8mm tape drives, see Upgrading and Repairing PCs, 11th Edition, which is included in printable PDF format on the DVD accompanying this book.

Choosing a Tape Backup Drive

Choosing a tape backup drive can be a simple job if you need to back up a single standalone system with a relatively small hard drive. The decision becomes more complex if the system has a larger hard drive or if you must back up a desktop system as well as a laptop. Choosing a tape backup drive type can be an even more complex program if you must back up a network server's hard drives and perhaps even back up the workstations from the server. As you ponder which backup tape drive you should select, consider the following factors:

• The amount of data you must back up

• The interfaces your equipment supports

• The data throughput you need

• The tape standard that is best for your needs

• The cost of the drive and tapes

• The capabilities and compatibility of the included driver and backup software

• Support for disaster recovery

By balancing the considerations of price, capacity, throughput, compatibility, and tape standard, you can find a tape drive that best meets your needs.

Note When purchasing a tape backup drive, take the time to look through magazines in which dealers or distributors advertise. Several publications specialize in PCs and carry advertising from many hardware and software distributors. I recommend publications such as Computer Reseller News and Computer Shopper. CNet's online shopping service (http://shopper.cnet.com) can help you locate multiple sources for both popular and rare items quickly. These publications cater to people or companies willing to go around the middlemen and buy direct. By reading such publications, you can get an excellent idea of the drives available and the price you can expect to pay. While reading about drive capabilities and prices, don't neglect to read reviews of the software included with each drive. Verify that the software capabilities match your expectations and needs. This is especially important if you intend to use the drive on a non–Windows system because most backup software today is tailored for Windows.

Capacity

The first rule for selecting a tape backup drive is to buy a drive with a capacity large enough for your needs, both now and for the foreseeable future. The ideal is to buy a drive with enough capacity so you can start your backup software, insert a blank tape in the drive, walk away from the system, and find the backup completed when you return. Because tape backups are generally rated by their maximum (2:1 compression) capacities—which is seldom reached in practice—you should calculate the "true" size of a tape backup drive by multiplying the native (noncompressed) capacity of a drive by 1.5 (equal to rating the drive as 1.5:1 compression). Thus, a so-called "20GB" tape backup might be better described as having a "15GB" capacity (10GB uncompressed times 1.5). Of course, the compressed capacity of a drive depends on the backup software you use, the settings you use, and the type of data you back up. Already compressed data, such as JPEG and GIF and some types of TIFF graphics files, can't be compressed further, whereas text and database files can be compressed significantly. If you find that you have higher or lower compression ratios during backup, use the compression ratio you normally achieve to help estimate your true backup capacity.

You should always ensure that your tape backup medium supports a capacity larger than your largest single drive or partition. This makes automated backups possible because you won't have to change a tape in the middle of a backup. And, even if you don't mind replacing tapes in the middle of a backup, a single-tape backup is safer. If the first tape of a multiple-tape backup is damaged or lost, the entire backup is unusable with most backup systems!

Tape Standards and Compatibility

The next most important consideration, after adequate capacity, is choosing a drive whose tapes meet a standard that is useful to you. If you have existing tapes you want to restore, or you receive tapes from other users that you must read, you need a drive that can work with those tapes. Use the backward-compatibility information listed earlier to help you decide on a drive to purchase if this feature is important to you.

If your ability to work with older tape media is only an occasional issue, you might prefer to buy a high-performance drive for current backups and maintain an older drive that matches the older standard. Most Travan-type and QIC-Wide drives can read QIC-80 tape cartridges, for example.

Tip It is important that you make a choice you can live with. If you manage a large installation of computers, mixing QIC, Travan, DAT, and 8mm drives among systems is seldom a good idea.

Software Compatibility

Equally important to your consideration is the software required to operate each drive. Currently, most parallel port and ATA drives come with software that runs under Windows operating system versions from 98 to XP. SCSI tape drives usually also support Windows NT, Windows 2000/XP, or Unix. USB-based drives are primarily designed for Windows 98/Me/2000/XP, although Windows 2000/XP might not support as many devices as Windows 9x/Me does. Check the manufacturers' Web sites for operating system compliance if your office's computers use more than one operating system.

Most operating systems have their own software for backing up data to a tape drive. If you intend to use this software, you should verify that the drive you purchase is supported by each piece of software on each system you intend to use with the drive. Third-party programs usually offer more features, but you might need to buy separate programs for the various operating systems your office uses.

Data Throughput

Any of the ATA, IEEE-1394a, or SCSI interface drives covered earlier should provide adequate performance (1MBps or above when backing up compressed data), but performance suffers if you opt for the convenience of USB or parallel port drives. Floppy-interface QIC, QIC-Wide, and Travan drives should be considered obsolete for large-drive backups because of the limitations of the floppy interface and their small capacities.

Cost

You can figure the cost per MB for a drive in two ways: media cost only (which is valid for users with an existing drive) or drive plus media costs (which is a better method for new purchasers). Regardless of your favorite choice(s) in removable storage, be sure to look at the total picture, taking into account the savings from multipack data and the benefits of the extra speed of SCSI and ATA.

Tip One point worth remembering when you evaluate whether to buy a tape drive is that the cost of the tapes and drive, taken as a whole, is nowhere near as high as the costs (in terms of frustration and lost productivity) of a single data-damaging hard drive problem. Considering that most people are more likely to back up a system if they have a tape drive installed than if they must use another medium for the backup, the cost of a drive and tapes is quite small, even on a standalone PC used mostly for fun.

Support for Disaster Recovery

Disaster recovery, which enables you to create a tape backup and floppy disk set that can be used to reinstall an entire operating system and data file set without installing Windows first, is a function of both the backup software and the drive interface. Disaster recovery is supported with most backup programs, but drives that connect to the USB or IEEE-1394a interfaces cannot support disaster recovery because they use Windows drivers. Because a disaster recovery data restore process starts in the MS-DOS mode, these drives can't be accessed because DOS lacks drivers for these ports.

Tape Drive Installation

Because most tape drives today use the same ATA, SCSI, USB, or parallel-port connection options that are used by other types of storage devices, you should see the appropriate sections of this book for more details about these devices:

• Chapter 14, "Physical Drive Installation and Configuration," provides detailed instructions for installing hard drives, floppy drives, and CD drives.

• Chapter 7 provides exhaustive coverage of the ATA interface.

• Chapter 8 provides detailed coverage of the SCSI interface.

• Chapter 17 provides information on USB and serial interfaces.

Note For more details about installing the older floppy-interface tape backup drives, see Upgrading and Repairing PCs, 11th Edition, available in printable PDF format on the DVD included with this book.

Tape Drive Backup Software

The most important decision you can make after you choose the tape standard and capacity of your backup tape drive is the backup software you will use with it.

The three sources for tape backup software are

• Software bundled with the drive

• Software bundled with the operating system

• Software obtainable from third parties

Use the following checklist to evaluate the software you plan to use with your tape backup drive:

• Device support. You might prefer to use tape for most backups, but can you change your mind and use high-capacity removable magnetic or optical storage if you need to? Some backup software bundled with a particular drive will work only with that drive; check whether a full version with more options is available.

• Compatibility with existing backups. If you have replaced an older tape drive with a new one, can the backup software as well as the tape drive read your old data?

• Adjustable compression options. If you are using a drive without hardware data compression, you should be able to adjust the compression methods used, or even turn them off to make sending the tape to the user of another drive easier.

• Data safety options. In addition to verification, good tape software should also include some form of ECC error correction to make recovering the data in case of media damage easier.

• Disaster recovery. Many bundled or operating-system-standard backup programs require you to reinstall the operating system before you can restore the contents of a crashed drive. Insist on a disaster recovery feature that will allow you to restore a drive from bootable disks and the tape backup without taking the time to reinstall the operating system first. Keep in mind that you need to use an ATAPI or SCSI drive to have support for disaster recovery as well as software with this feature.

Other useful features to look for include

• Unattended backup scheduling. Enables you to schedule a backup for a time when you won't need to use your computer

• Macro capability. Use when selecting options and the files to back up

• A quick tape-erase capability. Use when erasing the entire contents of a tape

• Partial tape-erase capability. Use when erasing only part of a tape

• Tape unerase capability. Use when recovering erased data

• Password-protect capability. Enables you to protect backup data from access by unauthorized persons

Read reviews, check compatibility, look for trial versions, and be sure to test the backup and restore features as you look for the best tape backup program for your needs.

Tip Backup software vendor Novastor (www.novastor.com) has a unique solution for a major problem caused by moving from an older backup system to a new one: What to do with the data on the older tapes? Its TapeCopy 2.0 software enables you to move data archives from your outmoded SCSI or ATA tape backup to a new SCSI- or ATA-based backup system. You can also use it to make hard disk copies of your tapes and to duplicate a backup tape on a similar drive. If you have extensive backup data and don't want to retain your old tape backup drive, TapeCopy 2.0 might be the answer.

Tape Drive Troubleshooting

Tape drives can be troublesome to install and operate. Any type of removable media is more susceptible to problems or damage, and tape is no exception. This section lists some common problems and resolutions. After each problem or symptom is a list of troubleshooting steps.

Can't detect the drive:

• For parallel port drives, use the tape backup as the only device on the drive and check the IEEE-1284 (EPP or ECP) mode required by the drive against the parallel port configuration.

• For USB drives, be sure you're using Windows 98 or higher and that the USB port is enabled in the BIOS; many systems originally shipped with Windows 95 have this port disabled.

• For ATA drives, ensure that the master/slave jumpers on both drives are set properly.

• For SCSI drives, check termination and Device ID numbers.

• For external drives of any type, ensure that the drive is turned on a few seconds before starting the system. If not, you might be able to use the Windows 9x Device Manager to refresh the list of devices, but if this doesn't work, you must restart the computer.

Backup or restore operation failure:

If your tape drive suffers a backup or restore operation failure, follow these steps:

Bad block or other tape media errors:

To troubleshoot bad block or other types of media errors, follow these steps:

Caution Note that most minicartridge tapes are preformatted and can't be reformatted by your drive. Do not attempt to bulk-erase preformatted tape because this renders the tapes unusable.

System lockup or system freezing when running a tape backup:

If your system locks up or freezes while running a tape backup, follow these steps:

Other tape drive problems:

Other issues that might cause problems in general with tape backups include

• Corrupted data or ID information on the tape.

• Incorrect BIOS (CMOS) settings.

• Networking problems (outdated network drivers and so on).

• A tape that was recorded by another tape drive. If the other drive can still read the tape, this might indicate a head-alignment problem or incompatible environment.

Tape Retensioning

Retensioning a tape is the process of fast-forwarding and then rewinding the tape to ensure that there is even tension on the tape and rollers throughout the entire tape travel. Retensioning is recommended as a preventive maintenance operation when using a new tape or after an existing tape has been exposed to temperature changes or shock (for example, dropping the tape). Retensioning restores the proper tension to the media and removes unwanted tight spots that can develop.

Some general rules for retensioning include the following:

• Retension any tapes that have not been used for more than a month or two.

• Retension tapes if you have errors reading them.

• Retension any tapes that have been dropped.

• In some cases, you might need to perform the retension operation several times to achieve the proper effect. Most tape drive or backup software includes a Retension feature as a menu selection.