Tape is the ideal medium for enterprise backup and recovery because it's fast, reliable, and affordable. Until recently, tape backup didn't offer the benefit of data separation from the enterprise server. SCSI distances are limited to 100 feet or less. Thus, tapes still had to be manually carried offsite. New channel extension technology makes direct offsite recording possible. Deemed remote electronic vaulting , data extension capabilities allow data transfer across unlimited distances.
Recent developments in automated tape libraries supporting virtually all computing platforms solve the automation problem. Automated libraries of all sizes abound, from the desktop version carrying a
The robot-controlled library and its partner—high-capacity/high-speed tape—can be located away from the prime processing sites and can be logically connected over great distances. The price of these lines is no longer a deterrent to good data protection and storage management practices.
StorageTek (STK), for example, makes robotic libraries that vary from a model that holds 18 tapes and one or more tape drives to the gigantic Powderhorn, which holds up to 6000 tapes and as many as 80 tape
Tape transports from StorageTek, IBM, and DLT can be attached to these robotic libraries, or even a mix of assorted transports. This allows the appropriate high-capacity tape drive to be matched with the robot depending on the specifications. By separating which library is needed and which tape transport is
Tape transports are also becoming increasingly more affordable as
Tape transfer speed, throughput, and reliability are major factors when you consider developing a backup/restore solution. Table E-2
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 (
|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|
|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|
|Recording technique||Linear||Helical||Serpentined longitudinal|
1 Data supplied by StorageTek, Inc.