| What's a "midrange" tape library?
The lines defining tape library categories are blurring and vendors disagree on where to draw those lines. For example, Hewlett-Packard Co., Qualstar Corp. and Sony Electronics Inc. call their respective ESL series, TLS series and CSM series tape libraries enterprise products, while comparable models from IBM Corp., Quantum Corp. and Sun Microsystems Inc.'s StorageTek are considered midrange by those vendors.
The extremes are fairly easy to classify. Units like Dell Inc.'s PowerVault 132T or Quantum's Scalar 24 each support a maximum of two tape drives and 20 to 40 tape cartridges, which clearly places them in the entry-level class. Conversely, tape libraries like IBM's 3484, Quantum's Scalar 10K and Sun's StorageTek StreamLine SL8500 plainly belong at the high end of the spectrum because they support hundreds of tape drives and thousands of tape cartridges. But when tape libraries fall in between those extremes, the library classifications become hazy.
For instance, the differences among tape libraries like IBM's TS3310, Quantum's Scalar 100 and Sony's CSM100 are slight. Quantum's Scalar 100 offers some midrange features like support for LTO or SDLT tape media and up to six tape drives. But tape library vendors tend to agree that capacity, not features, is the ultimate criteria when distinguishing between tape library classes. For the purposes of this article, the Scalar 100, with its support for a maximum of 72 cartridges, falls a bit short of our definition of a midrange library.
As a general rule, tape libraries can be classified based on the following capacity criteria:
- Entry level:
Supports one or two tape drives, and fewer than 50 tape slots
- Midrange:
Supports three to 11 tape drives, and 50 to 200 tape slots
- Enterprise:
Supports 12 or more tape drives, and more than 200 tape slots
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