« Wayback Wed: When MPE/iX wasn't for sale | Main | Why Support Would Suggest Exits from 3000 »

March 16, 2018

Fine-tune Friday: SCSI Unleashed

Seagate 73GB driveAlthough disk technology has made sweeping improvements since HP's 3000 hardware was last built, SCSI devices are still being sold. The disk drives on the 15-year-old servers are the most likely point of hardware failure. Putting in new components such as the Seagate 73-GB U320 SCSI 10K hard drive starts with understanding the nature of the 3000's SCSI.

As our technical editor John Burke wrote, using a standard tech protocol means third parties like Seagate have products ready for use in HP's 3000 iron.

SCSI is SCSI

Extend the life of your HP 3000 with non-HP peripherals

By John Burke

This article will address two issues and examine some options that should help you run your HP 3000 for years to come. The first issue: you need to use only HP-branded storage peripherals. The second issue: because you have an old (say 9x7, 9x8 or even 9x9) system, then you are stuck using both old technology and just plain old peripherals. Both are urban legends and both are demonstrably false.

There is nothing magical about HP-branded peripherals

Back in the dark ages when many of us got our first exposure to MPE and the HP 3000, when HP actually made disk drives, there was a reason for purchasing an HP disk drive: “sector atomicity.” 9x7s and earlier HP 3000s had a battery that maintained the state of memory for a limited time after loss of power. In my experience, this was usually between 30 minutes and an hour.

These systems, however, also depended on special firmware in HP-made HP-IB and SCSI drives (sector atomicity) to ensure data integrity during a power loss. If power was restored within the life of the internal battery, the system started right back up where it left off, issuing a “Recover from Powerfail” message with no loss of data. It made for a great demo.

Ah, but you say all your disk drives have an HP label on them? Don’t be fooled by labels. Someone else, usually Seagate, made them. HP may in some cases add firmware to the drives so they work with certain HP diagnostics, but other than that, they are plain old industry standard drives. Which means that if you are willing to forego HP diagnostics, you can purchase and use plain old industry standard disk drives and other peripherals with your HP 3000 system.

Connect just about anything to anything

SCSI stands for Small Computer System Interface. It comes in a variety of flavors with a bewildering set of names attached such as SCSI-2, SCSI-3, SE-SCSI, FW-SCSI, HVD, LVD SCSI, Ultra SCSI, Ultra2 SCSI, Ultra3 SCSI, Ultra4 SCSI, Ultra-160, Ultra-320, etc. Pretty intimidating stuff.

Don’t despair though. Pretty much any kind of SCSI device can be connected to any other with the appropriate intermediary hardware. Various high quality adaptors and cables can be obtained from Paralan (www.paralan.com) or Granite Digital (www.granitedigital.com).

So, SCSI really is SCSI. It is a well-known, well-understood, evolving standard that makes it very easy to integrate and use all sorts of similar devices. MPE and the HP 3000 are rather behind the times, however, in supporting specific SCSI standards. Support for LVD SCSI was added with the A- and N-Class systems—and with MPE/iX 7.5, these same systems would support Fibre Channel (FC). 

Let’s concentrate on the SE-SCSI and FW-SCSI interfaces, both seemingly older than dirt, and disk and tape storage devices. But first, suppose you replace an old drive in your system, where should you put it? The 9x7s, 9x8s and 9x9s all have internal drive cages of varying sizes. It is tempting to fill up these bays with newer drives and, if space is at a critical premium, go ahead.

However, if you can, heed the words of Gavin Scott.

I’d recommend putting the new drives in an external case rather than inside the system, since that gives you much more flexibility and eliminates any hassles associated with installing the drive inside the cabinet. It’s the same SCSI interface that you’d be plugging into, so apart from saving the money for the case and cable, there’s no functional difference. With the external case you can control the power of the drive separately, watch the blinking lights, move the drive from system to system (especially useful if you set it up as its own volume set), etc.

At sites such as Granite Digital you can buy any number of rack mount, desktop and tower enclosures for disk systems. Here is another urban legend; LDEV 1 must be an internal drive. False. Or, the boot tape device has to be internal. False. You cannot tell by the path whether a drive is internal or external, and the path is the only thing MPE knows (or cares) about the physical location of the drive.

Okay, there are some limits

Once you come to terms with the fact that you can use almost any SCSI disk drive in your HP 3000, dealing with SE SCSI is a piece of cake and a whole world of possibilities opens up. With the right cable or adapter (see Paralan or Granite Digital) you are in business.

But just because you can connect the latest LVD drive to your SE-SCSI adaptor, should you? Probably not, because you are still limited by the speed of the SE adaptor and so are just wasting your money. Now that you know you do not need the specific HP drives you once bought, you can pick up used or surplus drives ridiculously cheap. [Ed. note: the 73 GB drive at the top of the article is $129.]

Seagate created new technology drives with the old technology 50-pin SE-SCSI interface, the 18Gb model ST318418N and the 36Gb model ST336918N.

FW-SCSI is more problematic than SE-SCSI because no one even makes FW-SCSI (HVD) disk drives any more and you need more than just a simple cable or adapter to connect newer drives to an HVD adaptor. In fact, from the Paralan site, “HVD SCSI was rendered obsolete in the SPI-3 document of SCSI-3.”

So, what is one to do? Most systems with FW-SCSI adaptors need them for the increased throughput and capacity they provide over SE-SCSI. Paralan and others make HVD-LVD converters. The Paralan MH17 is a standalone converter that allows you to connect a string of LVD disk drives to an HP FW-SCSI adaptor. Pretty cool.

If you're on a Fibre Channel (FC) SAN environment and you would like to store your HP 3000 data on the SAN, then only the PCI-Bus A- and N-Class systems (under MPE/iX 7.5) support native Fibre Channel.

A quick word about configuring your new storage peripherals: Do not get confused by the seemingly endless list of peripherals in IODFAULT.PUB.SYS. And, do not worry if your particular disk or tape drive is not listed in IODFAULT.PUB.SYS. Part of the SCSI standard allows for the interrogation of the device for such things as ID, size, etc. DSTAT ALL shows the disk ID returned by the drive, not what you entered in SYSGEN.

When configuring in a new drives, just use an ID that is close. In fact, there is really no need for any more than two entries for disk drives in IODFAULT, one for SE drives and one for HVD drives so as to automatically configure in the correct driver. The same is true for tape drives.

Summary

Disk drives and tape drives are the devices most likely to fail in your HP 3000 system. The good news is that you do not need to be stuck using old technology, nor are you limited to HP only peripherals. The bottom line is you have numerous options to satisfy your HP 3000 storage needs, both now and into the future.

Special thanks go to Denys Beauchemin, who contributed significant material to this article.

07:41 PM in Hidden Value, Migration | Permalink

Bookmark and Share

Use our search engine to find 20 years
of HP 3000 news and articles

Comments

Comments

The comments to this entry are closed.