SCSI Problem

[Tim Seufert]

On Tuesday, December 3, 2002, at 04:27  PM, Drew Lane wrote:
>> Possibly... how's your chain terminated?  It could also be a drive 
>> that is somewhat slow to respond after a SCSI bus reset and doesn't 
>> always get caught by the bus scan.  What kind of a drive is it?
>
> I'm sure the drive at ID 0 is very slow; it's the original Mac 1GB 
> drive.
> It's main purpose is to load BootX, so I can get to Linux.
> Not sure about the speed.  One of those quantum fireball thingys.

Definitely slow if it's the original 1GB Fireball.  They were slow even 
back when they were new.  :)  However, I can't say that I've ever heard 
of one failing to show up in Linux before, and I don't recall such 
problems back when I was using a PowerMac 7500 with what was probably 
the same drive you've got.  Of course, that was back in the early days 
of the PowerMac port of Linux and the drivers have changed quite a bit 
since then...  for example, if the drivers now have a shorter timeout 
when scanning for devices, that could create problems for a 
slow-to-respond drive.

> The drive at ID 1 is fairly new.  It's a Western Digital 9.1 GB 7200 
> RPM Ultra 2
> (with a 80 pin to 50 pin adapater, I might add)
>
> As I recall, I've got it setup so that the drive at ID 0 is the last 
> one on the chain
> becuase that was the easiest way to arrange the internal scsi cable.
>
> Maybe I should try rearranging the order?

Perhaps, but an Ultra2 drive won't have built-in termination, so you 
won't be able to have termination if it's the last drive unless the SCA 
adapter has a jumperable terminator.

> BTW, the drive at ID 0 is just terminated with the jumper on the 
> drive. (I think!)
>
>> (Ya wanna buy a drive?  :)  I've got three 9.2 GB Cheetah 18XL drives 
>> (~35 MB/s, ~5ms seek) that got decommissioned a while back when I got 
>> a 15K RPM drive, and I haven't found a use for them since, so I guess 
>> it's time to find a new home for them...)
>
> Maybe, but the 9GB I just put in there was only $25.00
>
> Shoot, I'm not sure if the SCSI bus on this old Mac can go more than 
> 10 MB/s anyways.

It can't, so a Cheetah would kinda be overkill.  Depending on the type 
of Mac, you'll have either a 5 MB/s or 10 MB/s internal SCSI bus.