What real world write speed to an Exabyte can I expect?

[Karl-P. Huestegge]

In <LARRY.90Sep13141156 at focsys.uucp> larry at focsys.uucp (Larry Williamson) writes:
>I must write > 1 Gigabyte of data to a tape on a 386 system running
>Unix 3.2. It may be either an ISA bus (or EISA bus system if a scsi
>controller is available). I expect to use an Exabyte drive (what else
>would be faster?), an adaptec 1542 controller (for both tape and
>disk).
>What data rate should I expect to be able to maintain for the duration
>of the write?

I use an adaptec 1542B with a Tandberg SCSI-Streamer 320/525MB under
SCO-Xenix 2.3.
The drive comes into streaming mode with 150MB tapes, but not fully with
320MB tapes (it rewinds for a second after 5-7 sec of streaming).

In spite of that i get a real world transfer rate of 480 MB/h with 
the 320MB tapes. - The bottleneck is not the streamer, but the OS.
Under DOS it streams and i get a rate of 600MB/h (Adaptec Sytos).

So i doubt that an Exabyte will be faster. (If it cannot stream it's even
slower.)

>More importantly, how long would an operator expect to wait before
>they could remove the tape?

With my system he would wait 105 minutes, if you changed the cartridge
afer 52 min. (Otherwise you might wait longer :-)

Karl-Peter

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Karl-Peter Huestegge                       karl at robot.mbx.sub.org
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