Making the Choice
Only you can decide what is best for your situation. After reading about the backup options in this book, put together some sample backup plans; run through a few likely scenarios and assess the effectiveness of your choice.
In addition to all the other information you have learned about backup strategies, here are a couple of good rules of thumb to remember when making your choice:
> If the backup strategy and policy is too complicated (and this holds true for most security issues), it will eventually be disregarded and fall into disuse.
> The best scheme is often a combination of strategies; use what works.
Choosing Backup Hardware and Media
Any device that can store data can be used to back it up, but that is like saying that anything with wheels can take you on a cross-country trip. Trying to fit several gigabytes of data on a big stack of CD-RWs is an exercise in frustration, and using an expensive automated tape device to save a single copy of an email is a waste of resources.
Many people use what hardware they already have for their backup operations. Most consumer-grade workstations have a CD-RW drive, but they typically do not have the abundant free disk space necessary for performing and storing multiple full backups.
In this section, you learn about some of the most common backup hardware available and how to evaluate its appropriateness for your backup needs. With large storage devices becoming increasingly affordable (160GB IDE drives can be had for around $100) and prices falling on DVD recorders, decisions about backup hardware for the small business and home users have become more interesting.
Removable Storage Media
Choosing the right media for you isn't as easy as it used to be back when floppy drives were the only choice. Today, most machines have CD-ROM drives that can read, but not write, CDs, which rules them out for backup purposes. Instead, USB hard drives and solid-state 'pen' drives have taken over the niche previously held by floppy drives: you can get a 256MB drive for under $10, and you can even get capacities up to 16GB for good prices if you shop around. If your machine supports them (or if you have purchased a card reader), you can also use Compact Flash devices, which come in sizes up to 8GB in the Flash memory versions and 4GB for Hitachi Microdrives. Both USB hard drives and solid-state drives are highly portable. Support for these drives under Fedora is very good, accommodating these drives by emulating them as SCSI drives — the system usually sees them as /dev/scd1. Watch for improved support and ever-falling prices in the future. A 500GB USB hard drive costs about $150. The biggest benefits of USB drives are data transfer speed and portability.
FireWire (IEEE-1394) hard drives are similar to USB drives; they just use a different inter face to your computer. Many digital cameras and portable MP3 players use FireWire. Kernel support is available if you have this hardware. The cost of FireWire devices is now essentially zero, because many external drives come with both USB and FireWire as standard.
Compared to floppy drives and some removable drives, CD-RW drives and their cousins, DVD+RW/-RW drives, can store large amounts of data and are useful for a home or small business. Although very expensive in the past, CD writers and media are at commodity prices today, but automated CD changing machines, necessary for automatically backing up large amounts of data, are still quite costly. A benefit of CD and DVD storage over tape devices is that the archived uncompressed file system can be mounted and its files accessed randomly just like a hard drive (you do this when you create a data CD; refer to Chapter 7, 'Multimedia'), making the recovery of individual files easier.
Each CD-RW disk can hold 650MB-700MB of data (the media comes in both capacities at roughly the same cost); larger chunks of data can be split to fit on multiple disks. Some backup programs support this method of storage. After it is burned and verified, the shelf life for the media is at least a decade or longer. Prices increase with writing speed, but a serviceable CD-RW drive can be purchased for less than $20.
DVD+RW/-RW is similar to CD-RW, but it is more expensive and can store up to 8GB of uncompressed data per disk. These drives sell for less than $50.
Network Storage
For network backup storage, remote arrays of hard drives provide one solution to data storage. With the declining cost of mass storage devices and the increasing need for larger storage space, network storage (NAS, or Network Attached Storage) is available and supported in Linux. These are cabinets full of hard drives and their associated controlling circuitry, as well as special software to manage all of it. These NAS systems are connected to the network and act as a huge (and expensive) mass storage device.
More modest and simple network storage can be done on a remote desktop-style machine that has adequate storage space (up to eight 250GB IDE drives is a lot of storage space, easily accomplished with off-the- shelf parts), but then that machine (and the local system administrator) has to deal with all the problems of backing up, preserving, and restoring its own data, doesn't it? Several hardware vendors offer such products in varying sizes.
Tape Drive Backup
Tape drives have been used in the computer industry from the beginning. Tape drive storage has been so prevalent in the industry that the tar command (the most commonly used command for archiving) is derived from the words Tape ARchive. Modern tape drives use tape cartridges that can hold 70GB of data (or more in compressed format). Capacities and durability of tapes vary from type to type and range from a few gigabytes to hundreds of gigabytes with commensurate increases in cost for the equipment and media. Autoloading tape-drive systems can accommodate archives that exceed the capacity of the file systems.
Older tape equipment is often available in the used equipment market and might be useful for smaller operations that have outgrown more limited backup device options.
Tape equipment is well supported in Linux and, when properly maintained, is extremely reliable. The tapes themselves are inexpensive, given their storage capacity and their opportunity for reuse. Be aware, however, that tapes do deteriorate over time and, being mechanical, tape drives can and will fail.
