Choosing Your Backup Medium
| Leaving aside the warehouse full of terabytes, you need to decide how to store your backed up files. Making a copy of all the files on your hard drive and storing it on another partition on the same drive may be useful in some situations, but not when the drive goes bad. Given this reality, you must choose another medium to back up your files to. This section gives you a brief overview of your choices and includes some suggestions to help you find the right one for you. Mirrors and RAID ArraysA redundant array of inexpensive disks (RAID) setup offers a system administrator a great opportunity to have a real-time permanent copy of everything on a particular hard drive. Mirrors are additional volumes that contain an exact copy of whatever data is stored on the "parent" volume. Whenever an operation writes data to the parent volume, it is immediately written to the mirror volume as well. If the parent disk were to fail, the mirror disk can immediately take over, ensuring that data isn't lost. With relatively inexpensive hard drives available, this can be a great solution because, as we learned earlier, drives will always eventually fail. Be aware, though, that mirrors don't check for corrupt files on the parent. They will write corrupt files to their disks as easily as they write good files. For more information on setting up RAID arrays, see "Setting Up Mirror Disks and RAID Arrays" later in this chapter. Removable Storage MediaUsing some type of removable media is the standard backup solution for home and SOHO users. Although the 1.4MB floppy disk is slowly disappearing from the computing landscape, other, more robust, choices can make backups less of a painful experience. Anything that helps users get into the backup habit is a good thing. Besides ordinary floppies, these choices exist for removable storage. Zip DrivesSUSE Linux has excellent support for the large capacity floppy drives from Iomega. Coming in 100, 250, and 750MB sizes, these drives can play a role in your backup strategy. These drives also have a choice of connections, serial and USB, which make the drives quite portable. The drive-and-disk combination can be more expensive than comparable CD-R/RW combinations. Zip disks also have a history of experiencing the "click of death," with sudden wiping of the disk. This is not so much of a problem with newer drives, but it still happens. USB "Keychain" Drives and Solid-State Portable DrivesKeychain drives (called that because they are so small you can attach them to a keychain) are so cool you might have trouble thinking of them as part of a serious backup program. With these gadgets, you can buy 128MB of storage for around $25 and 1.5GB for around $150. Plug them into a USB port and copy any files you want. Keychain drives use flash memory to store data. USB-based portable hard drives are also coming down in price, with 80GB of storage for about $100, and 400GB for less than $500. SUSE Linux will identify these drives as SCSI storage and mount them like any other volume on your system. The key thing to remember about both types of drives is that you really need USB v2.0 to make the transfer time worthwhile. Older computers with USB 1.0 ports cannot take advantage of the tremendously higher speeds of the new ports. If you have room for another PCI card in your machine, you can add USB 2.0 ports to your system. FireWire DrivesThese portable drives use a different interface (IEEE 1394) than the USB drives do, but are otherwise similar. The interface is popular with portable music players and digital cameras. Most of these drives were created for the Macintosh platform, but the Linux kernel supports them. CD-RW and Recordable DVDFor newer computers that have some kind of built-in recordable CD or DVD drive, it's hard to debate other choices for your backup. CD-R disks hold 700MB of data and cost less than a dollar; CD-RW (Read-Write) disks are only a little more for the same amount of space. CDs are durable, compact, and provide a mountable file system. This makes them more versatile than tape for restoring files. They are less fragile than Zip drives and use a more mature technology than the keychain drives. Transfer speeds vary depending on the drive, but all are acceptable. You still have to be careful not to scratch the disk, but they can be protected by jewel cases. Recordable DVD drives are also now becoming part of new PC installations. DVDs can hold up to 4.4GB of data, and cost around $2. The only issue is that there are two incompatible formats for recordable DVDs: DVD-RW and DVD+RW. You need to know what format your drive supports and buy the appropriate disks. Lately, DVD±RW drives have become available that allow you to use either format. SUSE Linux provides several command-line tools to burn CDs and DVDs. The k3b utility gives you an excellent GUI interface for these applications, whether you run KDE or GNOME, and supports both DVD formats. To run k3b, simply open a terminal session and enter kb3 at the shell prompt. Network StorageAlthough enterprise-level systems can take advantage of Network Attached Storage (NAS) setups, where the backup storage volumes are on the network directly, rather than needing to be restored to a server, there are other options for the rest of us.
Tape Drive BackupTape drives have been the standard corporate backup medium for a long time. The TAR archive format for Unix, which groups individual files into a single "tarball" for easy retrieval, stands for Tape ARchive. Tape cartridges can hold up to 70GB of data (more if the data is compressed), although capacities can vary. Tapes are very reliable when maintained, but they do degrade over time. Tape drives can and do fail as well. Caution Tape drives can be fragile and must be cleaned, aligned, and maintained regularly. Do not risk your data by neglecting these tasks. |
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