Taking Shelf Management to New Levels
Shelf management is an increasingly important part of embedded computing systems used in Communications applications. Today’s standard system monitors perform basic monitoring of voltages, fans, and temperature. But, in order to achieve as close to 100% uptime as possible for High Availability systems, we need the functionality of a shelf manager. The various peripheral cards, power supplies (input voltage, output voltages and temperature), fan speed, airflow, and temperature need to be monitored and controlled closely. How can this be achieved in an open standard, compatible with established architectures for carrier class systems like CompactPCI and new architectures like AdvancedTCA?
Today’s basic shelf managers
Today’s typical shelf managers are generally proprietary solutions that are not conducive to other architectures and protocols. To offer more flexibility and lower costs, a modular solution for shelf management is needed. Currently, the PICMG 2.9 specification that is optionally incorporated in CompactPCI systems defines the implementation of the system management bus using the IPMI and IPMB protocols. But, how do we take these protocols, expand on them, and provide an intelligent solution to both PICMG 2.0 for CompactPCI and PICMG 3.0 for AdvancedTCA?
Expanding Performance of Shelf Managers
In addition to basic monitoring functions, shelf managers need to have a more active role with the thermal management and peripheral cards. To control heat build-up, it should assess the heat generated in various areas within the chassis and control the fan speeds in that section. Ideally, the shelf manager would be able to control each individual fan within the chassis. Each board can communicate through the IPMB, information on the maximum temperature, power load, interface, etc. The shelf manager will make adjustments based on the signals from the boards, as well as thermal sensors strategically placed throughout the chassis. Further, remote alarm signals can be sent to notify maintenance personnel. It may send an email or alarm signal to the maintenance department or even an outside company, stating the problem and saying that it will soon need repair. A provision for a standard-based interface could facilitate development, manufacturing, and field service of the unit.
To optimize performance for cPCI and ATCA systems, the shelf manager would monitor standard voltages like 3.3V, 5V, and 12V, as well as 48V. For redundancy, another important issue in carrier class systems, the shelf manager can be designed as dual units in a hot swap redundant mode. It would support redundant operation with an automatic switchover, where one shelf manager will be the active one, while the other is a backup unit.
It is also important to have a shelf manager with the capability of Electronic Keying as stated in the PICMG 3.0 specification. This will eliminate the need for mechanical keys by preventing an improperly placed board from initializing. Further, it would be beneficial for the shelf manager to be able to be programmed to know the topology of the backplane (Dual Star, Mesh, etc.) and know which slots are fabric slots and which are node slots. The backplane could also have one or two (for redundancy) SEEPROM’s programmed with the shelf information and interface with the shelf manager through an I²C interface. When a board is plugged into the system, the shelf manager would read information on the backplane links used by the board. Only links that are compatible with their connected peers across the backplane would be enabled.
Modularity and Flexibility
Elma Electronic Inc. has developed solutions to integrate modular shelf management options into their chassis platforms. The Elma IPM Sentry™ Shelf Manager has been designed to achieve these tasks and meet the needs of shelf managers mentioned above. (see Diagram #1) Based on the ShMM-300 from Pigeon Point Systems, shelf manager is a flexible platform for shelf and chassis management using the Intelligent Platform Management Interface (IPMI). The shelf manager has been developed for the new PICMG 3.0 specifications. However, it is also designed to be easily adapted for PICMG 2.0/2.16/2.17 specification families as a Baseboard Management Controller (BMC) interfacing with a dedicated Chassis Management slot. The software within the module is able to interface with several protocols.
The shelf manager also collects information on the Field Replaceable Units (FRU), such as hot swap peripheral boards. There are several digital I/O’s, input for a Master-only I²C bus as well as a dual IPMB buffered by LTC-4300 for hot insertion and removal onto a live backplane. It has the built-in intelligence to be programmed within a environmental range. For example, if the 5V falls below 4.75 (or whatever deviation is programmed), the shelf manager will detect this and send out an alarm so the problem can be fixed before it becomes a critical issue.
For thermal management, there is a tachometer input for up to eight fans, using a PWM output to control the fan speed. The thermocouple sensors can detect hot spots in the chassis and modify the speeds of individual fans to cool those specific areas. By focusing the fan speed on only areas where it is needed, the system saves its power resources, reduces acoustic noise, and maximizes efficiency.
Mechanical Compatibility
An attractive design would be to have a shelf manager based on a 3U x 160mm form factor carrier card. This will help enable use in both the ATCA and cPCI system environments. The carrier card would use the same PCB, but have a few minor configuration differences between the two versions. However, the result would be a flexible and cost effective solution for various chassis architectures.
Another possible solution is a shelf manager interface board that the shelf managers plug into and cable to the backplane. These can also be developed in IEEE1101.10 form factor for compatibility. Depending where these are placed in the chassis, they might take up a slot or may not. For example, Elma’s 4U ATCA chassis has this type of implementation where the IPM Sentry shelf manager is fixed-plugged into the upper portion within the unit, but outside of the card cage area. Therefore, the 4U unit still offers 5-slots. Finally, adapter cards are being created for cPCI and ATCA. A shelf manager would plug into one side (which has the same form factor in both versions) while the other side plugs into the backplane.
Conclusion
As carrier grade systems demand High Availability and reliability, shelf management plays an important role in achieving high performance. Geared towards these types of systems, the PICMG 2.0 specification for cPCI and PICMG 3.0 specification for ATCA need advanced shelf management solutions. Modular designs are being created today that meet these needs in a flexible, compatible solution.
TM – IPM Sentry is a trademark of Pigeon Point Systems.
Gary Hanson
Project Engineer
Elma Electronic
510-656-3400
www.elma.com
garyh@elma.com
Gary has over 20 years of experience in high-tech electronics. He is a Project Engineer for Elma Electronic Inc. and has been with the company since 2000. His duties include developing system monitoring and management solutions, testing and integration, and power management solutions. Previous experience includes engineering positions in the industrial computer and mil/aero community. This includes companies such as Sierra Systems and General Dynamics Space Systems. Gary graduated from Iowa State University in 1991 with a BSME.
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