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April 2003

SCSI is SCSI

How to extend the life of your HP 3000 with modern, non-HP peripherals

By John Burke

Ever heard a question like this? “We have an old HP6000 SCSI SE disk rack. It has been running four 2-gig drives for a long time. One of the drives recently failed and we are looking at our options for not only replacing the lost storage but also increasing our available disk space. We are a small company so we are looking for relatively inexpensive options. Does anyone know if there is a larger drive that will fit into that specific rack? Failing that, is there any way we can get a single 9Gb or 18Gb HP drive to replace the whole rack?”

This article will address two issues raised by the above question, show why they are false, 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 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.

These earlier systems used so much power that the best you could hope for with a reasonable-sized battery was to keep the memory alive. In a happy set of coincidences for HP, just as it was contemplating getting out of the disk drive manufacturing business, CSY was developing the 9x8 line of systems that required less power. A small UPS could keep everything including the disk drives running in these newer systems. This seemed superior to just saving the state of memory. It also meant CSY could use industry standard disk drives, thus reducing the system cost and helping HP make the decision to exit the disk drive market.

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.

So what, you say? Well, have you tried to buy a 4Gb or 9Gb 50-pin HP branded disk drive for your 9x7, 9x8 or 9x9 lately? HP does not sell them anymore. If you can even find one, a 4Gb SE or FWD 50-pin HP branded disk drive will likely run you at least $500 and a 9Gb SE or FWD 50-pin HP branded disk drive will likely run you at least $800. Oh, and by the way, no one is making new FWD drives anymore of any size.

What about tape drives? HP DDS2 and earlier drives, except for internal ones needed to boot the system, have long since gone off the support list. HP DDS3 drives go off the list this year I believe.

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. [For more than you ever wanted to know about the various SCSI definitions see www.paralan.com/glos.html or www.adaptec.com.

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. Until recently, only SE-SCSI (SCSI-2) and FW-SCSI (HVD) were supported. Support for LVD SCSI was added with the A- and N-Class systems and, with MPE/iX 7.5, these same systems now support Fibre Channel (FC). Also, MPE only supports a few types of SCSI devices such as disk, certain disk arrays, DDS, DLT and a printer.

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 (I once bought a 9Gb SE SCSI drive in its own enclosure with new power supply and fan for $54 at www.compgeeks.com.) However, you are still dealing with old drives and old technology. Seagate makes some 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.

But suppose your organization is moving to a Fibre Channel (FC) SAN environment and you would like to store your HP 3000 data on the SAN. Only the PCI-Bus A- and N-Class systems (under MPE/iX 7.5) support native Fibre Channel. A storage router feature can allow you to connect FW-SCSI adaptors to Fibre Channel resources (i.e. SAN). To the HP 3000, each LUN simply looks like a normal attached disk drive – the router device will be configurable via a web interface to handle all the really hard stuff. Way cool.

For tape storage systems, let me quote Denys. “As for tape drives, this is more problematic. First, get off DDS and get to DLT (4000/7000/8000) with DLTIV tapes. Whatever connectivity problems there are can be dealt with just like the disk drives. If you have a PCI machine, LTO or SuperDLT is the way of the future and they both require LVD connections. If you have a non-PCI machine, anything faster that a DLT8000 is wasted anyway because of the architecture.”

Note that while, as Denys says, LTO and SuperDLT are the “way of the future,” HP has not committed to supporting either on the HP 3000. SuperDLT should probably work on A- and N-Class systems using the existing DLT driver; however, I do not know anyone who has tried. LTO drives will require a new driver for the HP 3000, so we should probably not hold our breath on that one.

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 drive(s), 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

If you plan to homestead, even think you might, or think there is even the slightest possibility you will still be using your HP 3000 for some years to come, you need to start thinking about your storage peripherals. Now. 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. Here is a summary of what the experts I’ve quoted recommend you do.

If you can, trade in your older machines for the A-Class or N-Class models. Yes, the A-Class and some N-Class systems suffer from CPU throttling. (HP’s term. Some outside HP prefer CPU crippling.) However, even with the CPU throttling, most users will see significant improvement simply by moving to the A-Class or N-Class. [In the recent System Improvement Ballot (SIB), removing CPU throttling was far and away the number one item in the voting. However, HP has given no indication it will do anything about this, so it would be unwise to purchase a low-end A- or N-Class system in the hopes that you will get a “free” performance boost sometime in the future.] Both the A-Class and N-Class systems use the PCI bus. PCI cards are available for the A- and N-Class for SE-SCSI, FW-SCSI and Ultra-3 SCSI (LVD). You can slap in any drive manufactured today; by anybody. Furthermore, with MPE/iX 7.5, PCI fiber channel adaptors are also supported, further expanding your choices. An A- or N-Class system bought today should be going strong 10 years from now.

If for whatever reason you are going to homestead on the older systems or expect to use the older systems for a number of years to come, you have several options for storage solutions. For your SE-SCSI adaptors, you can use the new technology, old interface 18Gb and 36Gb Seagate drives. For your FW-SCSI (HVD) adaptors, since no one makes HVD drives anymore, you have to use a conversion solution. [You could of course replace your FW-SCSI adaptors with SE-SCSI adaptors, but this would reduce capacity and throughput.] One possibility is to use an LVD-HVD converter and hang a string of new LVD drives off each of your FW-SCSI adaptors. The other possibility is the Crossroads Systems router that allows you to connect from one to four FW-SCSI adaptors to up to two Fibre Channel (FC) resources (i.e. SAN). In all cases, get rid of those dusty old HP 6000 enclosures, disasters just waiting to happen.

As for tape drives, forget DDS and use DLT (4000/7000/8000) with DLTIV tapes. Whatever connectivity problems there are can be dealt with just like the disk drives. If you have a PCI machine, LTO or SuperDLT is the way of the future and they both use LVD connections, though whether HP will support either for the HP 3000 remains an open question.

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. Also contributing were Stan Sieler, Steve Dirickson, Wirt Atmar and Gavin Scott.

John Burke is the founder of Burke Consulting and Technology Solutions (www.burke-consulting.com), which specializes in system management, consulting and outsourcing. He has over 25 years experience in systems, operations and development, is co-chair of SIGMPE, and has been writing regularly about HP e3000 issues for over 10 years. You can reach him at john@burke-consulting.com.


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