Universal SGI disk solution: 15kRPM 300GB SCA SCSI drives

indigofan

Member
Jun 8, 2020
49
19
8
Most likely you are running into the issue from forcing Single-Ended (SE) mode on a Low Voltage Differential (LVD) bus.

The SCSI architecture for the Fuel should be running at least Ultra160 LVD (if not more). These are Low Voltage Differential signalling buses. Now for many SCSI adapters (that also have interactive firmware, like Adaptec). You could FORCE an LVD bus back into the Parallel SE mode. This is what 50-pin (Narrow) and 68-pin (Wide/Ultra-Wide) are. You CANNOT mix the two, a SCSI chain runs at the slowest bus standard of all devices present on it. So if you put an LVD device and an SE device on the same chain...they both need to run as SE (good luck with that in practice).

However (regardless of SGI), I've seen embedded SCSI controllers for servers that were LVD-only and absolutely threw a fit when you tried ANY SE devices. They hated it, refused to do it, and generally were considered LVD only. I assume the last SGIs were configured this way.

The adapter you got IS SE. Because it has 50 pin, this isn't an issue with active termination of the 68->50 pins...you're attempting to downgrade the actual SCSI signaling standard to an obsolete one (in terms of the Fuel's perspective).

You need to be use something like this: https://cs-electronics.com/product/adp-9018-sca80-68-lvdse-for-ultra23-and-ultra160320-1-form-factor/

Please note the need for this kind of thing is RARE, the need to change a SCA drive to Ultra160/320 68 pin connector was just was never an expected thing. So I understand your issues, but while SCA drives are cheap, that's not what the Fuel takes (which is odd, considering the other SGIs DO take them). So be extremely careful not to mix SCSI standards. You won't blow up anything, but you're forcing the controller to a whole other signalling protocol...and even thought it should work, I'm not surprised it's throwing a fit. Many Ultra SCSI controllers were not really tested for SE and many either have intermittent problems or just outright refuse to work on an old SE device.

My advise, either buy a normal Ultra160 HDD (or get the right adapter, if you can) and then put in a AHA-2940UW card in the FUEL to run external and internal SE devices off that card. (since that's the correct standard for that adaptec card).

I've seen entire SCSI LVD array enclosures that worked ONLY on LVD and any SE devices caused firmware crashes. It's a thing.
I'm going to try and reuse the adaptor in an Indigo, got it plugged into a 10K drive, and now the machine glows a glorious Green (hurray) but awaiting a monitor to see what's going on and or a serial cable to get to the next step in resurrecting an IRIS Indigo R4K.
 

siliboi

Member
Jan 4, 2021
61
10
8
Halifax Nova Scotia Canada
Is it possible to connect a 300gb to the back of an o2. Like the one elf uses? I was going to use some kind of scsi 3 cable to a 68-80 adapter. What cable would I use and what adapter should I get. Im quite confused about what cable works on the back of an o2 i assume female to female scsi 3 of some type about 3ft long would work?
 

Elf

Storybook
Feb 4, 2019
567
155
43
The O2 has a HD68 external SCSI-II connector on back; one could certainly attach an external SCSI enclosure containing one of the 15kRPM 300GB drives.

I would find an external SCSI enclosure that also has a HD68 connector on the back, and use an internal SCA to 68 pin adapter to connect the drive inside the enclosure. The cable between the enclosure and the O2 would then just be a regular HD68 to HD68 SCSI cable.

You may also need a terminator for the second port of the external SCSI enclosure, so I would pick one up as well if it does not offer built-in termination.

For reference see the O2 Workstation Hardware Reference Guide: Connecting External SCSI Devices.
 

siliboi

Member
Jan 4, 2021
61
10
8
Halifax Nova Scotia Canada
The O2 has a HD68 external SCSI-II connector on back; one could certainly attach an external SCSI enclosure containing one of the 15kRPM 300GB drives.

I would find an external SCSI enclosure that also has a HD68 connector on the back, and use an internal SCA to 68 pin adapter to connect the drive inside the enclosure. The cable between the enclosure and the O2 would then just be a regular HD68 to HD68 SCSI cable.

You may also need a terminator for the second port of the external SCSI enclosure, so I would pick one up as well if it does not offer built-in termination.

For reference see the O2 Workstation Hardware Reference Guide: Connecting External SCSI Devices.
Any recommended enclosures or cables or websites where I can buy/ links?
 

Elf

Storybook
Feb 4, 2019
567
155
43
Really this is just something you will have to go on eBay and find. There were many different manufacturers of these enclosures (and cables, terminators, etc.), and they are old enough that you aren't guaranteed to find one model or another. I would make sure you can visually identify the different types of SCSI connectors and understand what you want to connect and how, and then find what you need by looking around.

If you want a full solution already put together, it's possible one of the listed SGI resellers could do that.
 

Elf

Storybook
Feb 4, 2019
567
155
43
There was some discussion today in the SGUG Discord chat about the heat that these drives may put off, and I do think it is a question worth investigating! If you have data points, please add them!

First off is a Challenge S with a stock Nidec power supply:
Code:
challenge65 1% hinv
CPU: MIPS R4600 Processor Chip Revision: 1.0
FPU: MIPS R4600 Floating Point Coprocessor Revision: 0.0
1 100 MHZ IP22 Processor
Main memory size: 256 Mbytes
[...]
challenge65 2% uptime
  1:07pm  up 18 days, 15:04,  1 user,  load average: 0.04, 0.01, 0.00
challenge65 3%
Note the uptime of the machine, to specify that it has been running for some time so as to come up to temperature. Air temperature is 73F.

Just after removing the case and adding black electrical tape for emissivity:
FLIR0039.jpg


Measuring using a thermocouple:
Indy_15k-2.jpg


After putting a lid on it, the temperature dropped slightly despite the relatively tame airflow of the single fan in the Nidec supply and the hard drive being perhaps in the most disadvantaged location for cooling:
Indy_15k-3.jpg


The drive is one of the 15k 300GB HPs as previously mentioned:
Indy_15k-1.jpg


As a followup, people asked how the disk temperature was affected by load. After performing a rqsall -rescan /var/inst/.rqsfiles a few times followed by a dd if=/dev/zero of=/tmp/foo bs=512 count=1048576. In total the drive went up a degree or so, to 104.7F with the top on.
 
Last edited:

Elf

Storybook
Feb 4, 2019
567
155
43
Also worth mentioning as brought up by @LarBob, from the disk manual:
The maximum allowable continuous or sustained HDA case temperature for the rated Annualized Failure Rate (AFR) is 122°F (50°C). The maximum allowable HDA case temperature is 60°C. Occasional excursions of HDA case temperatures above 122°F (50°C) or below 41°F (5°C) may occur without impact to specified AFR. Continual or sustained operation at HDA case temperatures outside these limits may degrade AFR..
(Manual attached)

Additionally noted in Discord, it is possible that scsicontrol may be able to yield the internal temperature of the drive, e.g.:
Code:
challenge65 3# scsicontrol -l /dev/scsi/sc0d1l0
/dev/scsi/sc0d1l0:  Log page 0x2 (write err count), len=0x34
[...]
Log page 0xd, len=0xc
Parameter 0, len 0x2, flags 0
  00 2B
(See drive manual page 25)

2B presumably being 43C, or 109.4F internally (or on the PCB where a sensor is, etc.).
 

Attachments

Last edited:

weblacky

Active member
Jan 13, 2020
130
34
28
Seattle, WA
I won't go and fetch it but I remember Google doing a HDD study for a few years on HDD failure rates. While they had their favs and such, the conclusion was...dramatic increase in failure rates for drives continuously OVER 70F and for every 10F additional like a 50% chance of failure, increase.

Granted you need REALLY aggressive cooling to achieve 70F on these old drives...but once you're really too hot to hold in the hand...too hot (really). Now of course if you're just booting these for fun, occasionally, who cares. if you're actually going run them for 1 hour plus...then nope...get an SSD or a modem (slower) drive with high density to turn down the rotation speeds (or sleep aggressively).
 

Elf

Storybook
Feb 4, 2019
567
155
43
I expect most people have an indoor air temperature above 70F so if that is the target then it doesn't matter how much air you are moving over them or how little heat the machine puts out :p
 
Last edited:

weblacky

Active member
Jan 13, 2020
130
34
28
Seattle, WA
Which is why I used the term "very aggressive cooling", because most people run 72F temps (I run 65F-68F) in their homes. Regardless, that was the statement and I already headed it off at the pass by qualifying it.

But I'll reiterate, 70F is considered perfect, but that's costly. But once it's uncomfortably hot to hold in your hand, that's bad territory.
 

Elf

Storybook
Feb 4, 2019
567
155
43
Sure; if we are being pedantic, the manufacturer has already specified the acceptable temperature range of the drive for it to fall within their expected failure rate: 41-122F. That lines up with your statement of above 122F being uncomfortably hot to hold in your hand.

In any case this particular drive appears to be satisfactory in this particular Indy. I look forward to more data about the 15k drives in other machines.
 

Elf

Storybook
Feb 4, 2019
567
155
43
Some people were also curious about Indigo2 and I had a little bit of time.

Specifically this Indigo 2, with the same model drive and approximately the same 73F air temperature as with the Indy, having been powered on for about an hour for the temperatures to stabilize:
I2_15k-hinv.jpg


I2_15k-1.jpg


I2_15k-2.jpg


scsicontrol reports 0x26, i.e. 38C / 100.4F, a little higher than the case temperature similar to before.
I2_15k-scsicontrol.jpg


Overall a little bit cooler than the Indy, not too surprising since the machine has more air flow.
 

About us

  • Silicon Graphics User Group (SGUG) is a community for users, developers, and admirers of Silicon Graphics (SGI) products. We aim to be a friendly hobbyist community for discussing all aspects of SGIs, including use, software development, the IRIX Operating System, and troubleshooting, as well as facilitating hardware exchange.

User Menu