SCSI not detected at boot but is fine

[George Hester]

once the operating system is active. These are old Micropolis 9GB UW SCSI
drives. One whines a little bit. If I remove some othe IDE drives both
SCSIs are seen at boot. There is a rescan of SCSI devices but both still
not seen. When the Operating System gets to the desktop both SCSIs are
there and fine as shown in Device Manager. I installed a noise-reduction
300W Power Supply. Do you think I still don't have enough Watage? Thanks.

 

[Bob I]

SCSI BIOS enabled? Adaptec cards use Ctrl-A to get in and set the card.

 

[George Hester]

Yes it is enabled. For the one that is always found. SCSI ID0. The other
one SCSI ID1 is always a hit or miss thing. Sometimes it is found and other
times it is not. If I remove some of the IDE drives both are always found.
This all during the BIOS initialization. Sometimes that second SCSI is NOT
found in the BIOS but it is there when the op sys gets to the desktop.
Sometimes not.

--
George Hester
_______________________________

SCSI BIOS enabled? Adaptec cards use Ctrl-A to get in and set the card.

 

[William Asher]

Yes it is enabled. For the one that is always found. SCSI ID0. The
other one SCSI ID1 is always a hit or miss thing. Sometimes it is
found and other times it is not. If I remove some of the IDE drives
both are always found. This all during the BIOS initialization.
Sometimes that second SCSI is NOT found in the BIOS but it is there
when the op sys gets to the desktop. Sometimes not.

<snip>

If it really is the power supply, then disconnecting the ID0 drive and
leaving all the IDE drives connected should show that ID1 drive will always
be found. If it isn't then that would suggest to me there is something
wrong with the drive on ID1.

 

[George Hester]

Yes that seems reasonable. But wouldn't disconnecting a IDE so that ID01 is
always found lead to the same conclusion that it is PSU. I ask because that
is the test I have done. I was a little wary of disconnecting the SCSI
Harddrive at the start of the SCSI cable.

 

[William Asher]

Yes that seems reasonable. But wouldn't disconnecting a IDE so that
ID01 is always found lead to the same conclusion that it is PSU. I
ask because that is the test I have done. I was a little wary of
disconnecting the SCSI Harddrive at the start of the SCSI cable.

<snip>

There should be no problem disconnecting any of the connectors on the
SCSI cable. Position doesn't matter on an internal cable, or at least
I've never found that position was an issue.

If I understand the situation, when you disconnect the IDE drives from
the system, both SCSI drives are recognized consistently. When you
connect the IDE drives, the system always finds the scsi on ID0 but
inconsistently finds the drive on ID1. That just doesn't seem like a
faulty power supply to me, it seems more likely that the one scsi drive
on ID1 has gone bad. Therefore, I would try to reduce the system power
load but leave the IDE drives in the box and see if the drive on ID1 will
get recognized consistently. If it does, then maybe it is the power
supply. If it doesn't, then it is highly likely the drive has failed (or
maybe the controller has failed).

For what it's worth, you have long gone past the point where I would have
thrown the whole thing out or tried to teach it to fly by throwing it off
a cliff.

 

[George Hester]

Yes you almost got it. Not drives drive. Disconnecting one of the IDE
drives (there are three) the SCSI's never present an issue. Only when all
three IDEs are in use is there inconsistent finding of SCSI ID01. The
system has been going since I posted this 24/7 everything working just that
if I shut down and reboot the issue will probably return.

As for teaching it to fly...well the previous owners (hey might have been
you???) likely gave up and so shipped it to me. I'm just going to see if it
serves files which is really all I want it to do. Just serve files. It
does that I'm a happy camper.

 

[Alan C]

George,

2 things - first, 300w is insufficient for 3xIDE + 2xSCSI drives, you need
500w or bigger.
Second, Micropolis cards need an active SCSI terminator at the end of the
cable - auto-termination on the drives should be disabled.

 

[Colon Terminus]

George, it sounds as if you still nave a power supply problem. It is during
startup when drive enumeration happens and it is at this time that the most
demand is put on the power supply. You have, among other things, five hard
disks struggling to spin up to their rotational speed simultaneously. Its
during spinup that they draw the most current.

Remember all power supplies are not created equal. I have one machine with
eight hard disks in it that was having intermittent flakiness with a well
respected Brand A 560 watt TrueSomethingorOther power supply. I replaced the
power supply with a PC Power and Cooling 510 watt supply (I could've built
an entry level Linux PC for the cost of that power supply) and it solved the
problem. The PC Power and Cooling 510 watt supply was superior in power
output to the brand A supply rated (by them) 50 watts higher.

 

[George Hester]

Yes I fully agree with you on the PSU. I am in the market for a stronger
albeit quiet PSU. I really think I have to put up with this issue until I
can get a better one.

I do not have Micropolis cards. I have Micropolis SCSI drives. The cards
have the necessary termination on them. As far as I know the drives
themselves have nothing on them for "termination" but I could be wrong about
that. This is my first foray into SCSI.

--
George Hester
_______________________________

George,

2 things - first, 300w is insufficient for 3xIDE + 2xSCSI drives, you need
500w or bigger.
Second, Micropolis cards need an active SCSI terminator at the end of the
cable - auto-termination on the drives should be disabled.

 

[George Hester]

Yup that's what I am thinking. I got to find one that's quiet though. At
least quieter than the SCSI's themselves.

--
George Hester
_______________________________

George, it sounds as if you still nave a power supply problem. It is during
startup when drive enumeration happens and it is at this time that the most
demand is put on the power supply. You have, among other things, five hard
disks struggling to spin up to their rotational speed simultaneously. Its
during spinup that they draw the most current.

Remember all power supplies are not created equal. I have one machine with
eight hard disks in it that was having intermittent flakiness with a well
respected Brand A 560 watt TrueSomethingorOther power supply. I replaced the
power supply with a PC Power and Cooling 510 watt supply (I could've built
an entry level Linux PC for the cost of that power supply) and it solved the
problem. The PC Power and Cooling 510 watt supply was superior in power
output to the brand A supply rated (by them) 50 watts higher.