You can back up data anywhere you can record information. In some cases, you may even want to print out hard copies of key configuration files. Some personal desktop users may find 1.44MB floppy drives adequate. Workstation users may find that slightly larger capacity media such as 100MB Zip or 230MB Bernoulli drives meet their needs. In either case, users can back up just the critical files that they need, usually from their /home directory. Commands such as tar and cpio let you back up specific groups of files and or directories, as described later in this chapter.
For those with a need to back up gigabytes (GB) or even terabytes (TB) of data (1TB = 1000GB), there are three basic options: tape drives, writeable CDs/DVDs, and removable/external hard disks. If one tape or CD is not enough to back up your hard disk, hardware is available that organizes these systems into tape libraries and CD/DVD jukeboxes. One way to use hard disks for backups is discussed later in this chapter, in the section Understanding RAID.
All three types of media can be copied and transported to secure and remote locations. If your facility is destroyed by fire or some other disaster, the right media, properly stored, can help you restart your business or organization. Backups were tested on a large scale during the tragedies of September 11. Some businesses saved data in remote locations in real-time; others were able to get to their data in hours or days.
A number of other third-party software solutions are available; you might need their support if you have the amount of data that justifies a jukebox or a high-capacity tape drive. You ll find a list of third-party backup software and hardware manufacturers at www.storagesearch.com .
If you have the money, you can get a tape drive that can store your data nearly as fast as current IEEE 1394 hard drives. As of this writing, systems are available that can store nearly 30TB of data in over a 100 tape cartridges in a single box. With data transfer speeds of nearly 1000GB per hour , it is possible to fill this unit with a full backup in a single weekend .
Also available are lower capacity, less expensive tape drives with conventional interfaces, such as to parallel ports, IDE, and SCSI. Tape drives with these interfaces carry device names similar to hard drives with these connections.
There are also tape drives with USB and IEEE 1394 interfaces. As discussed in Chapter 02 , support for IEEE 1394 and many USB interfaces is still experimental, and they may not work with Red Hat Linux 9.
Compared to tape drives, writeable CDs and even DVDs seem to pale by comparison. A CD can hold only around 650MB of data; a DVD can hold just over 6GB of data. But a number of jukeboxes are available that can write data to literally hundreds of disks.
In addition, CDs and DVDs hold a number of advantages over tape drives. In proper environmental conditions (i.e., don t store your CDs in a hot and humid environment!), CDs and DVDs can last for a decade or more. Unlike with tape drives or hard disks, you can t accidentally erase them with a magnet . They are not susceptible to the electromagnetic pulses associated with nuclear explosions.