Comparing offline storage

 

Offline storage is data that you save on media that is separate from the system. 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 optical media. You can use virtual optical media to save to a virtual image, which is stored on your disk units. You can then copy that image to a CD or DVD, or distribute it over your network. It is important that you understand the differences among these different forms of media when you decide which one is right for you. The following table describes some of the differences:

Characteristic	Comparison
Access to data	Optical and virtual optical storage 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 25 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 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.

 

Parent topic:

Tape

Related concepts
Optical storage