PCI-SCSI Device Adapter Cards on HP e3000 N-Class and A-Class Systems
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Commercial Systems Division With the introduction of N-Class and A-Class Systems, new device adapter cards are required for the support of SCSI peripherals. These new cards also require new software and new SYSGEN configuration values. The purpose of this article is to provide an external "System Administrator" view of these changes in MPE/iX. The opening section of the article describes the new device Adapter cards. A small section on Card Performance and Device Connection limits is then provided for reference. Finally the closing section of this article is a review of SCSI Terminology (which you may want to read first if all of this is new to you). Note: Installation of HP e3000 Device adapter cards is to be performed by licensed HP Hardware personal only. All documents referred to in this article are available http://docs.hp.com. The configuration of these cards and attached SCSI devices using SYSGEN is covered in a separate article in this Communicator.
New Device Adapter Cards for N-Class and A-Class Systems
There are four new Device Adapter Cards available for the N-Class Systems: A4800A, A5149A, A5150A and, A5159A. A-Class Systems support two of these four cards: the A4800A and A5149A. Each of these cards can be plugged into one of the system PCI Buses and will present one or two SCSI Bus port(s) to the outside world. In addition, the N-Class and A-Class Systems each have a "Core I/O" card which includes modules that provide SCSI peripheral support. These Core I/O SCSI Buses are implemented using the same chip set(s) as the new Device Adapter cards and so can be treated as an embedded version of these new cards. A4800A - Single Port FWD SCSI-2 (PCI bus) Adapter Card. This card plugs into a PCI Bus on the system and presents a single SCSI bus to the outside world. This SCSI bus allows connections to High Voltage Differential (HVD) SCSI peripherals only. Historically on the HP e3000, HVD SCSI devices have been called "Fast/Wide" devices. This bus must be terminated using an HVD terminator; typically this is a High Density (HD) 68-pin HVD Terminator such as the C2905A. (Special Note: This card is not auto-terminating; it requires an additional physical terminator such as A4700-67098 (1252-6520) be installed on the card for proper bus operation. This terminator should be included with the card but can easily be lost if you are not careful.) For details see "A4800A PCI Ultra SCSI Host Bus Adapter Service and User Guide." A5159A - Dual Port FWD SCSI-2 (PCI Bus) Adapter Card. (N-Class Only) This card plugs into a PCI Bus on the system and presents two (2) independent SCSI buses to the outside world. These SCSI Buses allow connections to High Voltage Differential (HVD) SCSI peripherals only. (Historically on the HP e3000, HVD SCSI devices have been called "Fast/Wide" devices.) Each of these buses must be terminated using an HVD terminator; typically this is a High Density (HD) 68-pin HVD Terminator such as the C2905A. For details see "HP A5159A Dual Port PCI to Differential Ultra SCSI Host Bus Adapter Service and User Guide." A5149A - Single Port Ultra 2 SCSI (PCI bus) Adapter Card. This card plugs into a PCI Bus on the system and presents a single SCSI Bus to the outside world. This SCSI Bus is capable of operating in either LVD or SE Mode. This determination is made automatically by the card based upon the devices and termination present on the Bus; there is no software control for this feature. This bus must be terminated. Depending upon the cables/connectors being used, this would typically be either a High Density (HD) 68-pin LVD/SE terminator such as C2364A or, for Very High Density (VHDCI) 68-pin LVD/SE cables, a C2370A. For details see "HP A5149A PCI to Ultra2 SCSI Host Bus Adapter Service and User Guide." A5150 - Dual Port Ultra 2 SCSI (PCI bus) Adapter Card. (N-Class Only) This card plugs into a PCI Bus on the system and presents two (2) independent SCSI Buses to the outside world. These SCSI Buses are capable of operating in either LVD or SE Mode. This determination is made automatically by the card based upon the devices and termination present on the Bus; there is no software control for this feature. Each SCSI bus must be independently terminated. Depending upon the cables/connectors being used this would typically be either a High Density (HD) 68-pin LVD/SE terminator such as C2364A or, for Very High Density (VHDCI) 68-pin LVD/SE cables, a C2370A. For details see "HP A5150A Dual Channel PCI to Ultra2 SCSI Host Bus Adapter Service and User Guide." N-Class Core I/O Card. This card contains embedded versions of both an A5159A (Dual Port) and an A5149A (Single Port). The A5159A portion of the Core I/O card supports the two internal system disk slots - neither of these SCSI Buses are exported to the outside (i.e. there is no way to connect external peripherals to these buses). The A5149A portion of the Core I/O card presents a single LVD/SE bus for the connection of device(s) external to the system (VHDCI 68-pin LVD/SE connector). A-Class Core I/O Card. This card contains embedded versions of both the A5159A (Dual Port) and a A5150A (Dual Port). The system uses one port from each card to support a single internal disk and presents the other SCSI bus to allow the connection of external SCSI peripherals. Path 0/0/1/0 (from the A5159A) is provided with a VHDCI 68-pin LVD/SE connector. Path 0/0/2/0 (from the A5150A) is provided with a special HD 50-pin SE connector; this connector only supports an 8-bit data path so only "narrow" SCSI devices such as the DDS-3 Tapes may be connected.
SCSI Card Performance Limits and Device Connection Limits
(Primary source "A5149A PCI to Ultra2 SCSI Host Bus Adapter Service and User Guide") Table 4-1 SCSI Bus Widths and Speeds
| SCSI Classification | HP Card Id (signal type) | SCSI Bus Width (Bits) | Maximum Data Rate (MegaBytes/Sec) |
|---|---|---|---|
| SCSI-1 | HP28642A (SE) | 8 | 5 |
| Fast SCSI | HP28696A (HVD) | 8 | 10 |
| Fast Wide SCSI | " | 16 | 20 |
| Ultra SCSI | A4800A, A5159A (HVD) | 8 | 20 |
| Wide Ultra SCSI | " | 16 | 40 |
| Ultra2 SCSI | A5149A, A5150A (LVD/SE) | 8 | 40 |
| Wide Ultra2 SCSI | " | 16 | 80 |
SCSI-1 Devices were only certified to operate on the HP e3000 at SCSI-1 speeds. While it is possible that newer SE-SCSI disks are capable of working at higher speeds they are not certified to do so.
HP6000 Series Mass Storage products (a.k.a. "Cars" boxes) and High Availability Storage enclosures (A3311A, A3312A, a.k.a. "Jamaica") will not support transfers at higher than "Fast" speeds (e.g. Ultra or Ultra2).
A5616A "SureStore E Disk System HVD10" uses HVD signaling and LVD Disk modules but internal components are SE-SCSI based. Since SE-SCSI signaling is not defined at "Ultra2" speeds (see Table 4-2) this cabinet is limited to Ultra speeds.
If there is one or more SCSI-1 devices on a bus then the card will operate at "SCSI-1" speed.
Except where rule #1 applies the software will set the bus speed to "Fast."
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CAUTION: Overriding software defaults to operate devices at faster than certified speeds can cause erratic system behavior, hangs and even data corruption. |
| SCSI Classification | SE (Meters) | HVD (Meters) | LVD (Meters) | Maximum Allowed Devices (Note 2) |
|---|---|---|---|---|
| SCSI-1 | 6 | 25 | 12.5 | 8 |
| Fast SCSI | 3 | 25 | 12.5 | 8 |
| Fast Wide SCSI | 3 | 25 | 12.5 | 16 |
| Ultra SCSI | 1.5 | 25 | 12.5 | 8 |
| Ultra SCSI | 3 | -- | -- | 4 |
| Wide Ultra SCSI | -- | 25 | 12.5 | 16 |
| Wide Ultra SCSI | 1.5 | -- | -- | 8 |
| Wide Ultra SCSI | 3 | -- | -- | 4 |
| Ultra2 SCSI | Note 1 | Note 1 | 12.5 | 8 |
| Wide Ultra2 SCSI | Note 1 | Note 1 | 12.5 | 16 |
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CAUTION: Exceeding cable length maximums may cause erratic system behavior, hangs and/or data corruption |
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NOTE: Single-Ended and High-Voltage Differential protocols are not supported/defined at Ultra2 Speeds. |
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NOTE: This limit is based upon SCSI bus electrical and timing characteristics only. MPE/iX may further limit the number of devices allowed per bus based upon performance characteristics. Please see the "N-Class Supported Peripherals" Article in this Communicator for additional details. |
SCSI Terminology Primer
The SCSI Standard documents both the physical and electrical connection between devices. There are a large number of options and terms used to define the type of SCSI bus or device that one is using. Luckily, on the HP e3000 only a certain subset of these options have been supported. The most important characteristic to understand is the type of electrical signaling the device is capable of using. A secondary consideration is the type of connectors a device uses, which will influence your cabling options. We'll cover both of these items below.
SCSI Electrical Signaling Types:
At this time there are three different electrical signaling types: Single-Ended (SE), High Voltage Differential (HVD) and Low Voltage Differential (LVD). The original set of SCSI devices available on the HP e3000 are known as Single-Ended SCSI devices. These devices were typically connected via a 50 pin cable with 8 data bits (1 byte) and use +5 Volt signals to communicate at a peak rate of 5Mbytes per second. These devices are also referred to as a SCSI-1, Single-Ended Narrow or simply SE-SCSI. Examples of these devices include DDS Tapes like the HPC1530B or Disks such as the ST34573N which are typically connected to the HP28642A Device Adapter Card. On the N-Class and A-Class systems SE-SCSI devices are supported via connection to A5149A and A5150A PCI-SCSI Device Adapter Cards. A second type of SCSI device was introduced in the MPE/iX 5.0 release and is typically referred to as "Fast/Wide SCSI" or F/W SCSI. These devices are connected via a 68 pin cable with 16 data bits (2 bytes) and use a +-5 volt differential signal to communicate at up to 20 Mbytes per second. The term "Fast-Wide SCSI" is actually incomplete in defining the type of device being used; a more proper term would be High Voltage Differential SCSI (HVD) using Fast Wide signaling. Examples of these HVD devices include the DLT7000 Tape drive, numerous "Fast-Wide" Disks such as the HPC2490WD or ST39173WD, all of which are typically connected to the HP28696A Fast/Wide SCSI Adapter Card. On the N-Class and A-Class systems, HVD devices are supported via connection to A4800A and A5159A PCI-SCSI Device Adapter Cards. With the introduction of the N-Class and A-Class Systems, there is a new type of SCSI device available known as Low Voltage Differential (LVD) Devices. These devices are connected via a 68 pin cable with 16 data bits (2 bytes) and use a +-3.3 volt differential signal to communicate at up to 80Mbytes per second. As of the time that this article is written there are no fully LVD devices being supported on the HP e3000. The SCSI standard states that all LVD devices should have the capability of operating in SE-SCSI mode. Thus, the LVD Device Adapters that HP supports have the capability to support both Single-Ended and LVD devices. This means that it is possible for older SE-SCSI devices to be used with an LVD Device Adapter (though they will transfer data at the lower SE-SCSI rate). On the N-Class and A-Class systems, LVD devices would be supported via connection to A5149A and A5150A PCI-SCSI Device Adapter Cards.Physical Connectors and Cables
With these different electrical characteristics, there are also different physical connectors. At this time HP supports devices that use four different types of physical connectors: Low Density (LD) 50-Pin (example DDS-2 C1530B), High Density 50-Pin (HP28642A Device Adapter Card), High Density (HD) 68-Pin (HP28696A Fast/Wide SCSI Adapter Card) and Very High Density (VHDCI) 68-pin (A5149A, Single Port Ultra 2 SCSI (PCI bus) Adapter Card). This means there are a large number of cable types in varying lengths, some with different connectors on each end (LD50 -> HD50 or HD50 -> HD68 or HD68 -> VHDCI68, etc.) When ordering cables pay particular attention to the type of connectors present on each device you are connecting. The type of physical connector does not explicitly dictate the type of electrical signals that can be used. For instance SE, HVD and LVD signals can all be transmitted through a 68-pin cable with High Density connectors, but NOT at the same time! Hooking up SE devices to HVD devices (or vice versa) can actually damage the devices; so be cautious. Just because you can physically connect doesn't mean that you should. (The complexity of this issue is one reason that we recommend that all peripheral installation be done by HP Technicians.)|
Chapter 4 PCI-SCSI Device Adapter Cards |
SCSI Device Configuration Examples for N-Class and A-Class HP e3000 Systems |