[TriLUG] will a SCSI tape slow down my SCSI disks?

[Neil Roeth]

On Nov 18, Daniel Monjar (daniel.monjar at na.biomerieux.com) wrote:
 > Mandrake 9.2 on Intel
 > 
 > (scsi0:A:0): 160.000MB/s transfers (80.000MHz DT, offset 127, 16bit)
 > (scsi0:A:5): 10.000MB/s transfers (10.000MHz, offset 15)
 > (scsi0:A:6): 160.000MB/s transfers (80.000MHz DT, offset 63, 16bit)
 >   Vendor: FUJITSU   Model: MAJ3182MP         Rev: 5508
 >   Type:   Direct-Access                      ANSI SCSI revision: 04
 >   Vendor: Quantum   Model: DLT4000           Rev: D069
 >   Type:   Sequential-Access                  ANSI SCSI revision: 02
 >   Vendor: IBM       Model: DDYS-T18350N      Rev: S93E
 >   Type:   Direct-Access                      ANSI SCSI revision: 03
 > 
 > 
 > I've had to add a quantum SCSI tape to the same adapter that handles my 
 > SCSI disks.  Is the tape drive slowing down the disks in any way?  Ages ago 
 > when I was configuring SCSI DEC systems (VMS 6.2) I was cautioned about 
 > mixing slow and fast devices on the same bus, because transfer would happen 
 > at the speed of the slow device.  Still true?

>From the manual for the Adaptec 2940U2W adaptor:

"We recommend keeping your Ultra2 hard disk drives separate
from your non Ultra2 peripherals. Connecting a non Ultra2
hard disk drive to the Ultra2 connector on the SCSI Card
2940U2W causes the Ultra2 SCSI segment of the SCSI bu s to
drop down to Ultra SCSI performance levels (40 MBytes/sec)."

For this reason, I bought a second adaptor for the SCSI CD-R that I put into a
machine with SCSI Ultra2 drives.

-- 
Neil Roeth