Technology Tip of the Month

Methods

Backup on floppy disks

This method works well if you have relatively little on your hard drive or in conjunction with one of the other methods, such as CD-ROM backup. You can use the brute force method and just drag the files you want onto a floppy. If you use a program such as CopyDoubler, you can choose to copy only files that have changed. A backup program (see the section on software below) will tell you how many disks you'll need and prompt you to put them in as necessary.

If you have something you really don't want to lose, make sure you back it up in more than one place: two disks, tape and disk, etc. Also keep in mind that data on floppy disks deteriorates more rapidly than that on any of the other media, with a three- to six-month assured lifespan. It will generally last far longer, but you can't count on it.

Tape backup

Backing up on tape is a relatively fast method if you use DAT drives. These have come down in price enough to be affordable by most institutions (around $1000), and hold 2-8 gigabytes. This is a more reliable medium than floppy disks, but you may have problems if you store data for more than a year. You also need to be careful to avoid magnetic fields, as with floppy disks. (Don't put the tape cartridge on top of the hard drive, for example.) The main advantages of tape backup are large capacity, small size (with 4mm tape), and relatively cheap media--about $25 for a tape that can store up to 8GB of information.

Removable drive backup

A number of options exist now for removable drives. Here the factors to look at are capacity, speed, size, and cost. Removable drives generally hold less than tape, but last longer. Popular types of removables include:

• Optical drives
  Current optical drives hold between 128MB (for about $500) and 2.6GB (around $2000). Optical disks cost between $15 (128MB) and $70 (2.6GB) each. The drives and the disks are fast, small, and very reliable; it is difficult to damage an optical disk. These disks tend to have shelf lives counted in years.
  
  
• Syquest drives
  Syquest drives hold between 44MB and 270MB. The smaller capacity drives are larger in physical size, slow, and quite cheap. Currently popular models are 100MB (about $200) and 270MB (about $450). Cartridges cost $70-$80 each. In the past, Syquest cartridges have been very sensitive and unreliable. Current models are better, so buying an older, used Syquest is not recommended.
  
  Syquest's newest line consists of the EZ135 (about $130) and EZ230 (about $300), drives sized and priced to compete with Iomega dries (see below). These drives are small, fast, and reliable. They are not as fast as hard drives, but still good enough to use as an external drive.
  
  
• Iomega drives
  The market for removables changed dramatically with the introduction of Zip drives from Iomega. At less than $200 for a drive and about $20 per 100MB cartridge, it became the removable for everyone. Like EZ drives from Syquest, Zip drives are small, fast, and reliable. Iomega also offers a Jaz drive that holds 1GB for about $500; 1GB cartridges cost about $125 each.
  
  

Network backup

If you are on a network, the system administrator can set up remote backups to a networked tape drive or other networked drive. Backing up over a network is much slower than most other methods, so it's generally automated and done late at night when everyone has gone home. If set up correctly, this can be the most efficient way to protect all the data on a network.

Mirror/RAID backup

If you have two or more hard drives, you can create a duplicate of your hard drive on a second drive. Specialized software does this automatically, and it's most often used to protect the data on a server where the consequences of a hard drive crash are greatest. Generally speaking, it's overkill on a personal machine.

CD-ROM backup

The price of CD-ROM recorders has dropped dramatically recently, comin down well below $1000 for a basic model. Because you can't change the information on a CD-ROM, this method works best for permanent information such as applications. Look for multi-session software so that you can record more tracks later, taking advantage of the 600MB capacity of the CD-ROM.

Unlike other storage options, CD-ROMs are not affected by magnetic fields. They can be taken through airport security safely and have a shelf life measured in decades. Do note, however, that recordable CD-ROMs are far more fragile than commercial music CDs and care must be taken to avoid scratching the data side. These should always go into a CD case when not in use.

Some optical drives now are combination optical and CD-ROM recordable drives; while more expensive (around $2000), this can be a good option if you have both short-term and long-term storage needs.

Backup software

• Incremental backup: This means that the program will copy only the changed files, reducing backup time considerably.
  
  
• Unattended backup: This lets you set a time and series of actions for the backup so that you do not need to be present. It works well with a tape or optical drive. You put the tape or optical disk in the drive and leave the computer on; the backup can then take place at the programmed time, such as 3am, when you are not using the computer. (Midnight hackers may want to set the backup for 7am.)
  
  
• A variety of media: Make sure you have the option to back up in a variety of ways, whether to tape, optical drive, floppy disks, etc.
  
  
• Archive or disk image: This lets you choose whether to copy files individually or to copy the disk as a whole. If your backup is just in case of major disk emergency, such as a crash so severe you need to format the hard drive, the disk image option is the best. It is the quickest way to restore a whole drive.
  
  However, if you are thinking about restoring just one or two files--say earlier versions of a database--then you need the file-by-file archive option.