How much faster is virtual tape than real tape?
A high performance tape drive, such as LTO3 is rated at over 100MB/sec, but with tape marks, I/O block size and systems utilization, these speeds are rarely if ever achieved. A DSI virtual tape system is built on a high performance RAID disk system with an average access time of 4-5 milliseconds. Because it is emulating tape, its performance characteristics are not the same. Tape marks and I/O starvation do not require the performance killing repositioning that actual streaming tapes require. A DSI virtual tape system is up to 25 times faster than the tape drives that it emulates.
