43P-260 SCSI bus

[Morsing]

I'm a bit pussled by what my tells me (from diag):

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scsi1 P2/Z2 Wide/Ultra-2 SCSI I/O Controller
scsi0 P2/Z1 Wide/Fast-20 SCSI I/O Controller

scsi0 is the internal adapter, the drawing on the CEC cover and lsattr on the disks confirms this.
lsattr agrees with what diag says.
Is there any logic behind this? Can I somehow connect the disks to the external adapter? (Strange solution).

Thanks for any suggestions.

P.S. The reason I started investigating this was serious performance issues with the disks.

Cheers

Henrik Morsing
Certified AIX 4.3 Systems Administration
& p690 Technical Support

 

[aixmurderer]

Yip, it's possible. You will need a special external disk casing with built-in supply to do so though. The same port can also be used for an external SCSI tape drive, or you can daisy chain them together with a terminator on the last unit.

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[Morsing]

But what's the point of using a Fast-20 channel internally?
Also, lsattr says the external one is LVD/SE and the internal one is an SE mode. This sounds even more strange, doesn't it?

I'm just trying to make sense of this.

Cheers

Henrik Morsing
Certified AIX 4.3 Systems Administration
& p690 Technical Support

 

[aixmurderer]

Not sure of the 43P 260 housing, but if it's anything like the 43P 133's we have then you are basically restricted to 2 HDD's and a CD in the box.

So you are quite right, why use a slower controller which support 16 addresses internal, while opting for a faster, but only 8 addresses controller for external drives?

I know on the internal bus we had some older 50 pin 2GB drives, but replaced them with 68 pin 9GB drives. Perhaps the choice of the internal controller was based on backwards/forwards compatability?





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