CD-ROM, CD-RW, and DVD Drives

Your server should include a CD-ROM, CD-RW, or rewritable DVD drive. The following are some of the benefits of including these types of optical drives in a server:

• Easy installation of server operating systems, service packs, and drivers from CD media

• Image or file-by-file backup to rewriteable media (particularly with DVD media) if you choose a rewritable DVD drive

The following sections are designed to help you choose the right optical drive for your server installation.

Specifications

Optical drive standards for computers can be divided into two major types:

• CD (CD-ROM, CD-R, CD-RW) The maximum capacity of these drives is 703MB (80-minute CD-R media).

• DVD (DVD-ROM, DVD-RAM, DVD-RW, DVD-R, DVD-R DL, DVD+RW, DVD+R, DVD+R DL) The maximum capacity of these drives for single-layer media is 4.7GB; for dual-layer media the maximum capacity is 8.5GB.

A CD-ROM drive can read any of the listed CD formats, although a universal disc format (UDF) reader program might be required to enable data to be read from CD-RW media created using drag-and-drop applications such as DirectCD, InCD, DLA, and others. Currently, all Windows Serverbased operating systems are distributed on CD media, as are commercial Linux distributions. Downloadable Linux distributions are usually provided as International Organization for Standardization (ISO) CD images and must be burned to a recordable CD before installation.

If you plan to use other types of backup media for backing up server data, a CD-ROM drive is sufficient for now. However, in most cases, a DVD-ROM drive is about the same price as a CD-ROM drive, and using a DVD-ROM drive in a server enables you to read both CD and single-layer DVD media. In the near future, it's possible that vendors might start distributing business applications or operating systems on DVD media. Some PC games are already available on DVD.

When hard disk drives were 10GB or smaller, backing up data with a rewritable CD drive using CD-RW or CD-R media made sense. However, with even entry-level servers now featuring 40GB or larger hard disks, rewritable CD drives are typically inadequate.

Although some server vendors might offer combo DVD-ROM/CD-RW drives, you're better off getting a dual-layer rewritable DVD drive if you plan to use DVD media for backups. Such drives can write to almost any DVD or CD media. (However, most do not support DVD-RAM.) Keep in mind that even if you use dual-layer media, you have a native capacity of 8.5GB (but data compression can store up to twice this amount on the media). For drives over 40GB, you should consider using disk-to-disk or tape backup units.

For more information about server backup technologies and strategies, see Chapter 9, "Backup Operations."

CD/DVD Interfaces

Early optical drives (CD-ROM, CD-R, and CD-RW) used various categories of the SCSI interface. Although SCSI continues to be a popular choice for high-speed RAID arrays in all types of servers, SCSI optical drives have not been produced for several years.

Virtually all CD and DVD optical drives currently on the market use the Advanced Drive Electronics/AT Attachment (ATA/IDE also known as parallel ATA [PATA] or Enhanced IDE [EIDE]) interface. If a server uses ATA/IDE for the hard disk and for optical drive interfacing, you should connect the hard disk to the primary ATA/IDE interface on the motherboard and the optical drive to the secondary ATA/IDE interface to improve throughput.

See "ATA Standards," p. 409 and "PATA," p. 413, for details on the ATA/IDE interface.

A few high-end rewritable DVD drives now use the Serial ATA (SATA) interface discussed in Chapter 6, "The ATA/IDE Interface." Although SATA uses thin data cables and offers higher potential throughput, rewritable DVD drives using the SATA interface, while more expensive than ATA/IDE drives, offer little or no additional performance.

CD/DVD Host Adapters

Virtually every server has at least one PATA 40-pin host adapter on the motherboard. This can be used for an ATA/IDE-based CD or DVD drive. If the server also uses a PATA hard disk, it's preferable to place the hard disk and host adapter on separate cables rather than connect them as master and slave on a single cable. Although each PATA host adapter can support two drives, throughput is faster when each drive is located on its own host adapter.

Many recent servers have a mix of PATA and SATA host adapters, or a mix of PATA and SCSI host adapters. In such cases, the 40-pin PATA port can be used for a CD or DVD drive, and the SATA or SCSI host adapters can be used for hard disks.

CD/DVD Installation and Troubleshooting

You install CD and DVD drives the same way you install any other drive that uses the same interface. In the case of PATA drives, the drive is jumpered as master or slave if a 40-pin cable is used. If the superior 80-pin cable is used, cable select is the preferable jumpering method. No jumpering is required in the case of SATA optical drives; you just plug the drive in to power and data cables.

See "SATA," p. 424 for details on the Serial ATA interface.

If a rewritable DVD or CD drive will be used for data backups, compatible backup software must be installed after the drive is installed. See the vendor list on this book's CD-ROM for examples of server backup products.

Caring for Optical Media

By far the most common causes of problems with optical discs and drives are scratches, dirt, and other contamination. Small scratches or fingerprints on the bottom of a disc should not affect performance because the laser focuses on a point inside the actual disc, but dirt or deep scratches can interfere with reading a disc.

To remedy this type of problem, you can clean the bottom surface of a disc with a soft cloth, but you need to be careful not to scratch the surface in the process. The best technique is to wipe the disc in a radial fashion, using strokes that start from the center of the disc and emanate toward the outer edge. This way, any scratches will be perpendicular to the tracks rather than parallel to them, minimizing the interference they might cause. You can use any type of solution on the cloth to clean the disc, so long as it will not damage plastic. Most window cleaners are excellent at removing fingerprints and other dirt from discs and don't damage the plastic surface.

If a disc has deep scratches, you might be able to buff or polish them out. The Skip Doctor device made by Digital Innovations (see www.skipdoctor.com) can be used to make the polishing job easier.

Most people are careful about the bottom of discs because that is where the laser reads, but the top is actually more fragile. This is because the lacquer coating on top of the disc is very thin, normally only 67 microns (0.240.28 thousandths of an inch). You should write on discs only with felt tip pens that have compatible inks, such as a Sharpie or a Staedtler Lumocolor, or other markers specifically sold for writing on CDs. In any case, remember that scratches or dents on the top of a disc are more fatal than those on the bottom.

Read errors can also occur when dust accumulates on the read lens of an optical drive. You can try to clean out the drive and lens with a blast of canned compressed air or by using a drive cleaner (which can be purchased at most stores that sell audio CDs).

If your discs and your drive are clean, but you still can't read a particular disc, your trouble might be due to disc capacity. Many older CD-ROM drives are unreliable when they try to read the outermost tracks of newer discs, where the last bits of data are stored. You're most likely to run into this problem with a CD that contains a lot of data. If you have this problem, you might be able to solve it with a firmware or driver upgrade for your CD-ROM drive, but you may have to replace the drive.

If you have problems reading a particular brand or type of recordable or rewritable disc in some drives but not others, you might have a poor drive/media match. You should use the media types and brands recommended by the drive vendor. You should test backup media in other drives to ensure the backup can be read in case of emergency. If you have problems reading media on another system, you might want to reduce the burn speed; media written at slower burn speeds can be easier for some drives to read. As an alternative, some vendors supply utility software with their rewritable drives that enables the strength of the recording laser to be varied (for example, Plextor's PlexTools Professional's VariRec; see www.plextor.com for details).

If you are having problems with only one particular disc and not the drive in general, you might find that your difficulties are in fact caused by a defective disc. You should see whether you can exchange the disc for another to determine whether that is indeed the cause.

Handling Failure to Read a CD/DVD

If your drive fails to read a CD or DVD, you can try the following solutions:

• Check for scratches on the disc data surface.

• Check the drive for dust and dirt; use a cleaning disc.

• Make sure the drive shows up as a working device in System Properties.

• Try a disc that you know works.

• Restart the computer (the magic cure-all).

• Remove the drive from Device Manager in Windows, allow the system to redetect the drive, and then reinstall the drivers (in a plug-and-playbased system).

Handling Failure to Read CD-R and CD-RW Discs in a CD-ROM or DVD Drive

If your CD-ROM or DVD drive fails to read CD-R and CD-RW discs, you can try the following solutions:

• Check compatibility; some very old 1x CD-ROM drives can't read CD-R media. Replace the drive with a newer, faster, cheaper model.

• Many early-model DVD drives can't read CD-R and CD-RW media; check compatibility.

• The CD-ROM drive must be MultiRead compatible to read CD-RW because of the lower reflectivity of the media; replace the drive.

• If some CD-Rs but not others can be read, check the media color combination to see whether some color combinations work better than others; change the brand of media.

• Record the media at a slower speed. The pits/lands created at faster speeds sometimes can't be read by older drives.

• If you are trying to read a packet-written CD-R created with Adaptec/Roxio DirectCD or Drag to Disk on a CD-ROM drive, reinsert the media into the original drive, eject the media, and select the option Close to Read on Any Drive.

• Download and install a UDF reader that is compatible with the packet-writing software used to create the CD-RW on the target computer. If you are not sure how the media was created, try using the universal UDF reader/media repair program called FixUDF! (also included as part of WriteCD-RW! Pro) from Software Architects. WriteDVD! Pro includes the similar FixDVD! UDF reader/media repair program for DVD drives.

Handling Failure to Read a Rewritable DVD in a DVD-ROM Drive or Player

If your DVD-ROM or DVD player fails to read a rewritable DVD, you can try the following solutions:

• Reinsert the DVD-RW media into the original drive and finalize the media. Make sure you don't need to add any more data to the media if you use a first-generation (DVD-R 2x/DVD-RW 1x) drive because you must erase the entire disc to do so. You can unfinalize media written by second-generation DVD-R 4x/DVD-RW 2x or faster drives. See your DVD-RW disc-writing software instructions or help file for details.

• Reinsert the DVD+RW media into the original drive and change the compatibility (bit) setting to emulate DVD-ROM. Check with the drive vendor for details.

• Make sure the media contains more than 521MB of data. Some drives can't read media that contains a small amount of data.

Handling Failure to Create a Writable DVD

If you can't create a writable DVD but the drive can be used with CD-R, CD-RW, or rewritable DVD media, you can try the following solutions:

• Make sure you are using the correct media. +R and R media can't be interchanged unless the drive is a DVD±R/RW dual-mode drive.

• Be sure you select the option to create a DVD project in your mastering software. Some CD/DVD-mastering software defaults to the CD-R setting.

• Select the correct drive as the target. If you have both rewritable DVD and rewritable CD drives on the same system, be sure to specify the rewritable DVD drive.

• Try a different disc.

• Contact the mastering software vendor for a software update.

Handling Failure to Write to CD-RW or DVD-RW 1x Media

If you can't write to CD-RW or DVD-RW 1x media, you can try the following solutions:

• Make sure the media is formatted. Use the format tool provided with the UDF software to prepare the media for use.

• If the media was formatted, verify that it was formatted with the same or a compatible UDF program. Different packet-writing programs support different versions of the UDF standard. You should use the same UDF packet-writing software on the computers you use or use drives that support the Mount Rainier standard.

• Make sure the system has identified the media as CD-RW or DVD-RW. Eject and reinsert the media to force the drive to redetect it.

• Contact the packet-writing software vendor for a software update.

• The disc might have been formatted with Windows XP's own limited CD writing software instead of a true UDF packet-writing program. In this case, erase the disc with Windows XP after transferring any needed files from the media; then format it with your preferred UDF program.

• Contact the drive vendor for a firmware update. Be sure to follow the drive vendor's instructions carefully. A failed firmware update renders the drive useless.

Handling Problems with an ATAPI CD-ROM or a Rewritable CD or a DVD Drive Running Slowly

AT Attachment Packet Interface (ATAPI) is a term used to refer to CD-ROM or other optical or removable-media drives that connect to an ATA/IDE interface. If your ATAPI CD-ROM or rewritable CD or DVD drive performs poorly, you can check the following items:

• Check whether the drive is set as the slave to your hard disk; move the drive to the secondary PATA host adapter, if possible.

• Your PIO (programmed I/O) or Ultra DMA (UDMA) mode might not be set correctly for your drive in the BIOS; check the drive specs and use autodetect in BIOS for the best results.

See "The ATA/SATA Drive Configuration Submenus," p. 304, for details on autodetecting ATA/IDE and SATA hard disk drives.

• Check that you are using busmastering drivers on compatible systems; install the appropriate drivers for the motherboard's chipset and the operating system in use.

• Make sure buffer underrun-prevention settings are enabled in the CD or DVD mastering program.

• Make sure the latest drive firmware is installed.

Handling Trouble Reading CD-RW Discs on a CD-ROM Drive

If you can't read CD-RW discs in your CD-ROM drive, you can try the following solutions:

• Check the vendor specifications to see whether your drive is MultiRead compliant. Some drives are not.

• If your drive is MultiRead compliant, try the CD-RW disc on a known-compliant CD-ROM drive (a drive with the MultiRead feature).

• Insert CD-RW media back into the original drive and check it for problems with the packet-writing software program's utilities.

• Insert CD-RW media back into the original drive and eject the media. Use the right-click Eject command in My Computer or Windows Explorer to properly close the media.

• Create a writable CD or DVD to transfer data to a computer that continues to have problems reading rewritable media.

Handling Trouble Reading CD-R Discs on DVD Drive

If your DVD drive can't read a CD-R disc, check to see that the drive is MultiRead2 compliant because noncompliant DVDs can't read CD-R media. Newer DVD drives generally support reading CD-R media.