Choosing a Tape Platform
Tape transfer speed, throughput, and reliability are major factors when you consider developing a backup/restore solution. Table E-2 compares three of the leading tape transports.
Specifications such as these can help you judge which drive would suit a particular business's needs. For example, StorageTek's 9840 cost per cartridge is more than twice the cost of IBM's 3590, but it boasts longevity and better wear on the tape cartridge. The Sony DTF-1 features a transfer speed of 12 MB/sec but because of tape load times, the actual recall time is slower than StorageTek but faster than IBM. Gathering figures such as these and constructing your own tables is the best way to decide which figures are important and which are superfluous.
Table E-2. Comparing tape transports
| Tape Attribute | StorageTek 9840 | Sony DTF-1 (GY-2120) | IBM Magstar B11 |
|---|---|---|---|
| U.S. list purchase price | $27,400 | $12,500 | $32,500 |
| Data transfer rate | 10 MB/sec | 12 MB/sec | 9 MB/sec |
| Access time (sec, load + init) | 4 sec | 7 sec | 27 sec |
| Average recall time (sec, load + init + search) | 11.6 sec | 42 sec | 62 sec |
| High speed search (meters/sec) | 8-10 | Not published | 5 |
| High speed search (MB/sec) | 656 MB/sec | 300 MB/sec | Not published |
| Throughput 1 GB (average recall time + transfer rate) | 111.6 sec | 125.3 sec | 205.6 sec |
| Cartridge costs (U.S. $) | 20 GB $90 | 42 GB (GW730L) $120; 12 GB (GW240S) $50 | 10 GB $30 |
| Maximum drives per silo frame | 20 | 0 | 4 |
| Interface | Ultra SCSI, Fibre & ESCON | SCSI Fast & Wide | Ultra SCSI & ESCON |
| Native capacity | 20 GB | 42 GB and 12 GB | 10 GB |
| Storage capacity | 80 GB | 108 GB and 31GB | 30 GB |
| Compression | LZ1 (4:1) | ALDC (2.59:1) | LZ1 (3:1) |
| Media type | ½ metal particle | ½ metal particle | ½ metal particle |
| Midpoint load | Yes | Yes | Yes |
| Recording technique | Linear | Helical | Serpentined longitudinal |
1 Data supplied by StorageTek, Inc.
EAN: 2147483647
Pages: 366