The primary issue from a user's point of view is what you need to do with the data that is being stored.

• Are you using the data actively, continuously?

• Do you have government regulations on storage?
  • Does the storage have a time limit (i.e. IRS)?
  • Does the storage have data that must be secured (encrypted)?
  • What are the cost trade-offs of offline storage?
  • What are the risks for each media type of offline storage?

• is the media being used for compatability with other users, OS's, instrumentation or other special needs?

While DVD/CD is slow, their permenance is excellent, their size is relatively small and I don't have to worry much about hardware failures or demagnification. This makes DVD/CD great for IRS records, Sarbanes-Oxley, Drafting Records, Medical and some other Government record keeping.

Offline HDD is fast, but the hardware can fail over time and the disks can become demagnetized (the earth has a magnetic field, then there's gamma rays, x-rays and cosmic rays from space,...).

Tape is cheap, slow and sometimes limited. Demagnification issues exist as with HD, but also suffers from stretch and heat sensitvity.

DVD+/-RW, CD-RW is very slow vs the read only disks, but does have the advantage of being erased and written over. Bad for permanent record keeping, great for easily updated file storage.

Playing each of these issues against each other is important from the user's perspective. Consider a SOHO (mine):

Darkstar has 2 80G HD's, 1 27GHD for a total of 187G of storage.

Backup consists of multiple formats:

• Travan 3 floppy tape
• 1.2G QIC tape cartridge
• 4mm DAT
• 8mm DAT
• CD-R/CD-RW
• DVD+/-RW, DVD+/-R
• Bernoulli 150 disk
• Syquest 40, 80 and 200 disk
• Zip 100 disk
• Jaz 1G disk
• Digital Audio Cassette

Travan 3 gives me 1.6G/3.2G slow backup/restore, read capability of down to QIC-80 tapes. I have compatability with old archives and other users who have such media.

1.2G QIC cartridge gives me fast streaming backup and compatability to read down to 60M tapes. I have an old Viper drive that can get down one step lower. This covers a lot of archive tapes in many different operating systems.

4mm DAT is higher density offline storage, great for backing up directories for a short period of time (2-3 years). Low cost. Also gives me compatability with other systems that use 4mm DAT.

8mm DAT is higher density than 4mm DAT (5/10G), gives me compatability with many different systems as needed.

CD-R/CD-RW is great for music, pictures and "permanent" archiving of data. Limited to 680M, but very cheap on the pocket book. ATA drives take a hit on system performance while SCSI runs merrily along without consuming large amounts of PC resources.

DVD+/-RW, DVD+/-R is more expensive, runs faster and stores more. Otherwise, it has the same constraints as CD. Downside is that it is an ATA drive which means that my system slows down extremely considerably during operation. I take a hit on other performance during writing of the disk.

Bernoulli 150 disk mostly for compatability with others with Bernoulli disks. I know people with them and still use them.

Syquest 40, 80 and 200 disk Same as with the Bernoulli disk. This was a major favorite with Mac users and I know quite a few.

Zip 100 disk: the parallel port drive is a slow clunker, but the ATA and SCSI drives are as fast as slow HD's. Good for fast sneaker nets, quickly erasble, disks are cheap. Lots of people have them, it's fairly portable and the parallel port beast will connect to anything with a parallel port and a driver.

Jaz 1G disk, SCSI only. Fast large storage with the advantages of the Zip drive. The disk can be removed for safe keeping (i.e. I can put it in a safe). Downside is Iomega is the only source for disks and they want too much for them.

Digital Audio Cassette - fast little streaming tape, limited to 205M, but is compatable with a large number of instrumentation I've had to use. Once I have the data on the cassette, I can transer it to other media as applicable.

For the major part, I'm using the 8mm, 4mm, CD-RW and DVD-RW for offline storage based on the amount of data to be stored and for how long.