Comparing offline storage

It is important that you understand the differences among different forms of media when you decide which one is right for you. Use the table provided to determine your preferred form of media.

The most common forms of offline storage are tape media and optical media. Although optical media is becoming more prevalent, tape media is the most common media. Another option that you can use is virtual media. You can use virtual media to save to a virtual image, which is stored on your disk units. You can then copy that image to media, or distribute it over your network.

The following table describes some of the differences:

Characteristic	Comparison
Access to data	Optical and virtual optical media provide random access, whereas tape provides access to data sequentially.
Capacity	The lowest capacity tape has a similar capacity to DVD-RAM, but medium range and high-capacity tapes typically have 10 to 50 times the capacity of optical.
Compression	The system uses software compression to save compressed data to your optical media. This process takes considerable processing unit resources and may increase your save and restore time. Most tape media devices use hardware compression, which is typically faster.
Cost	Because you can store a larger amount of data on tape, tape has a lower cost per GB.
Data transfer rates	Data transfer rates for tape tend to be much higher than for optical media, particularly if you use tape drive compression.
Number of media passes or mounts	Optical media can be mounted anywhere from 50000 to 1 million times, depending on the type of media used. The number of media passes supported by tape varies, but is typically lower than optical media.
Reusability	Not all optical media is rewritable. Some optical media are write-once media, which means that after they are written to, they cannot be reused. Tape is reusable.