Power management strategy to support hot swapping of system blades during run time
A hot swappable system is described. It included software controlled hot swapping operations which provided a graceful booting or power-down of the system. In the even of force insertion or extraction of the system blades, a set of hardware features (such as using different pin lengths in the connectors and dampening resistor) prevents these types of operations from damaging the system hardware or affecting the operation states of other blades within the system.
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1. Field of the Invention
The invention relates to the field of systems with hot swappable components.
2. Prior Art and Related Art
In many applications it is necessary to have a system which remains in operation even when under repair. For instance, a server in a network may have boards or blades in a standby mode or with excess capacity. When a blade is detected as having failed, other blades that were in a stand-by mode take over while the failed blade is replaced. Alternatively, blades with excess capacity are used to pickup the tasks of the failed blade while it is replaced. Generally, an alarm or other indication is given to an operator indicating that a failure has occurred. The operator is then able to remove the failed blade and reinsert a good blade. One of the major problems in these systems is the management of power as these changes occur.
Often in such systems connectors are used having pins of different lengths which cooperatively engage sockets. For instance, a backplane in a server may have a plurality of connectors, each for receiving a blade where the pins in the connectors are of different lengths. These pins are used for instance, to allow discharge of static electricity as well as other functions.
A system is described having a backplane bus and a plurality of blades or boards which may be extracted or inserted while the system is in operation. This is often referred to as “hot swapping.”
In the following description, numerous specific details are set forth, such as specific voltages in order to provide a thorough understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known circuits and other components have not been set forth in detail in order not to obscure the present invention.
The present invention is described in connection with a server having hot swappable blades. Referring to
In one embodiment, the server includes several different units which may be hot swapped and which engage the backplane bus. These include the two server management blades (MBs) shown in
While not shown in
The present invention provides operating characteristics for the server which meet the predetermined criteria shown below in a table.
In the table above the hot swap states include P0 which is the state where the board is removed from the backplane and P1, the states where a blade is fully inserted into the backplane. The state H0 through H3 indicate several operational states for the blade as indicated in the above table. The “Yes” in the last three columns of the table indicate that the CPU blade, switch blades and SMBs support the indicated hot swap states.
While the server operates primarily on 48V DC there is also a 3V or 5V standby power used for a sleep mode. The state of that power is shown under “5V stby” in the above table. The system also employs a reset signal which is discussed below and shown in the table. The power management apparatus of the present invention, as will become apparent from the description below, provides the capability shown in the table.
Each of the blades includes a power supply which, in one embodiment, is a DC-to-DC converter for filtering and regulating the 48V power. The converter is enabled with an enable signal as will be discussed. The state of the converter is shown as either “off” or “on” in the above table.
One of the major problems in a hot swappable system is providing power to the blades and maintaining the power when the blades are hot swapped. The removal and insertion of blades often causes transients in the power delivery system which affect the operation of other blades and the power subsystem.
In one embodiment of the present invention each of the blades includes a female connector and a corresponding male connector in the backplane having pins of three different lengths. This is shown in
While typically the male connector is part of the backplane and the female connector is on the blade, in another embodiment the male connector may be on the blade and the female connector in the backplane. In this patent “pin/socket” is sometimes used to indicate that either the pin or the socket is being designated, depending on whether the backplane has the male or female connector. The term pin/socket indicates, for instance, that the socket cooperatively receives a pin of a designated length.
As is apparent from
Each of the blades includes a power supply which in one embodiment is a 48V DC-to-DC converter. As shown in
The input terminal to the converter receives power from two different lines. A first lines 114 is connected to the shortest length of the three pin/socket lengths (pin 115 and socket 122). The input terminal 110 also receives power from a long pin/socket namely pin 106 and socket 121. This pin/socket is connected to the input terminal 110 through a resistor 116. This resistor as will be discussed, plays an important role in dampening transient currents to the blade. The ground connection to the blade is through a long pin/socket.
The data signals are connected to the medium pins/sockets such as through pin 103.
Referring again to
The lines 26 which are the system management (SM) bus provide control signals from the MBs 10 and 12 to the other blades in the system. Among the signals provided as shown at the blade 15 are a reset signal, a converter enable signal shown as “DC—DC on” and the non-maskable interrupt (NMI) signal. All of the signals discussed in connection with lines 26 and 27 may be encoded onto a serial bus such as the I2C bus for distribution to the blades.
In one embodiment there are two server MBs 10 and 12. One of these two blades is active and the other is in stand-by. Lines 25 in one embodiment comprising a separate bus interconnecting the MBs 10 and 12. This bus provides a signal between the MBs indicating the health of the MBs. For instance, the inactive MB may periodically ping the active MB to determine its health. If the inactive blade determines that the active MB has failed it can power up and take over the system management. To this end, a multiplexer (e.g., MUX22) is used at the output of each of the MBs to allow the selection of appropriate SM bus signals. EEPROMs on the MBs (such as EEPROM 21) allow each MB to be prepared to take over at anytime since each stores the data needed for continued operation of the system.
Thus, while one of the MBs handles the housekeeping chores, the other one acts as a hot spare. The peer-to-peer heartbeat monitor (or similar implementation) as mentioned is used for one blade to monitor the status of the other blade. If the active management blade fails to respond to the heartbeat “pinging,” that blade is considered to fail and the hot spare blade takes over. A failure LED on the face plate of the failed management blade turns on and an alert is sent out by the hot spare to warn a system administrator of the failure event.
Referring now to
Now the MB 54 deasserts the reset signal allowing the newly inserted blade to boot up. This is indicated by the line 57. At H2 indicated by 58, the inserted blade indicates that it is on and healthy by the health bit over the backplane or over a separate SM bus. At H3 indicated by 59, normal operation of the inserted blade occurs with the blade operating system or embedded software up and running.
The normal insertion and extraction is obviously the easier case to deal with from the standpoint of power management and power transients.
As shown by line 76, as the blade is extracted the short pins/sockets of the connector such as pin 102 and socket 120 of
At this time the “power good” signal is deasserted and the health bit is deasserted as shown by line 76. As indicated by line 77, the MB 54 deasserts the enable signal for the converter. This is done to prevent a re-powering up of the blade if the blade were to be reinserted immediately. If this were not done and the blade was immediately reinserted, the large capacitance associated with the output of the converter would be immediately coupled through the short pin providing the direct connection to the 48V power supply. This would cause an unwanted transient which may affect other blades in the system.
Next as indicated at 80, the medium length pins/sockets break contact. These include the data signals associated with the CPU and switching blades. At 81 the long pins/sockets break contact. Among the long pins that break contact at this point is the 48V power supply which is coupled to the input of the converter through the resistor 116 of FIG. 5. Both on extraction and on reassertion this resistor dampens the transients associated with decoupling and decoupling the converter from the backplane. This is particularly important if, for example, for some reason the power supply remains enabled during immediate reassertion. If this were to occur, the first power applied to the converter would be through the resistor 116 dampening the surge which occurs when the converter is abruptly activated. By the time the shortest pins/sockets make contact this transient will have diminished. As also indicated at 81 the stand-by power being on one of the longest pins/sockets also breaks contact.
Thus, a power management system has been described for a system having hot swappable blades.
1. A hot swappable blade comprising:
- an enableable power supply having enable and power input terminals and a power output terminal, to provide power to circuitry on the blade connected coupled to the power output terminal in response to receiving an enable signal on the enable terminal;
- a connector having first, second and third pin/sockets, the first pin/socket being longer than the second and third pin/sockets;
- the first and second pins/sockets being operatively coupled to the power input terminal of the enableable power supply and the third pin/socket operatively coupled to the enable terminal of the enableable power supply; and
- an impedance element connected between the first pin/socket and the power input terminal.
2. The blade defined by of claim 1, wherein the third pin/socket is approximately the same length as the second pin socket.
3. The blade defined by of claim 2, wherein the connector includes a plurality of fourth pins/sockets for receiving data, the fourth pins/sockets having a length intermediate between the first and second pins/sockets.
4. The blade defined by of claim 1, wherein the connector includes a plurality of data pins/sockets for receiving data, the data pins/sockets having a length intermediate between the first and second pins/sockets.
5. The blade defined by of claim 1, wherein the power supply is a DC-to-DC converter.
6. The blade of claim 1, wherein the circuitry includes a processor, and the connector includes a reset pin/socket by which to receive a reset signal may be received to reset the processor.
7. The blade of claim 1, wherein the blade may be used in a system including a backplane to which the blade may be connected coupled via the connector, and the connector further includes a presence pin/socket used for determining if the blade is properly connected coupled to the backplane.
8. The blade of claim 1, wherein the connector further includes a power good pin/socket by which the blade can to assert a power good signal.
9. The blade of claim 1, wherein the connector further includes a health pin/socket by which the blade can to assert a health signal signifying the to signify blade health or blade failure of the blade.
10. The blade of claim 1, further comprising a failure light-emitting diode (LED) by which the blade can to indicate a failure status.
11. A system comprising:
- a backplane bus;
- a plurality of blades each having a connector to engage couple to the backplane bus including two management blades (MBs) and a plurality of other blades (OBs);
- each connector having first pins/sockets of a first length, second pins/sockets of a second length and third pins/sockets of a third length; the first length being the longest length, the third pins/sockets being the shortest length and the second length being longer than the third length and shorter than the first length;
- the backplane bus having power lines which cooperatively engage to provide power through one of the first pins/sockets and one of the third pins/sockets on each of the blades, wherein each of the blades includes a resistor connected to the one of the first pins/sockets that receives power from the power lines.
12. The system defined by of claim 11, wherein data is communicated among the blades over the backplane a bus in the backplane through the second pins/sockets on each of the blades.
13. The system defined by claim 11 wherein each of the blades includes a resistor connected to the one of the first pins/sockets that receives power from the power line.
14. The system defined by of claim 13 11, wherein each of the OBs provides a signal indicating to indicate its presence in the backplane over one of the third pins/sockets.
15. The system defined by of claim 14, wherein each of the OBs includes a DC-to-DC converter which is enabled by an enable signal received over one of the third pins/sockets from the backplane a bus in the backplane.
16. The system defined by of claim 15, wherein the enable signals for the OBs originates from one of the MBs.
17. The system defined by of claim 15, wherein each of the OBs provides a signal to at least one of the MBs indicating to indicate the status of its DC power.
18. The system defined by of claim 17, wherein the system is a server.
19. The system defined by of claim 18 including an additional bus in the backplane connecting to the MBs.
20. The system defined by of claim 19, wherein signals indicating are communicated over the additional bus to indicate the health of the MBs is communicated over the additional bus.
21. The system defined by of claim 20, wherein the OBs include a plurality of central processing unit blades and a plurality of switch blades.
22. The system defined by of claim 11, wherein the system is a server.
23. The system of claim 11, wherein one of the two management blades initially operates as an active management blade and the other operates as a standby management blade, and wherein the standby management blade is configured to monitor an operating status of the active management blade, and in response to determining the primary management blade is not operating properly, the system enables the standby management blade to take over operations previously performed by the active management blade, thus becoming a new active management blade.
24. The system of claim 23, wherein the system is further configured to annunciate a status indicator on the management blade that is initially the active management blade in response to detection that that blade has failed.
25. The system of claim 11, wherein the backplane comprises a backplane bus.
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- PC Card Standard, Release 7.0—Personal Computer Memory Card International Association (PCMCIA)/Japan Electronics and Information Technology Industries Association (JEITA), Published Feb. 1999.
International Classification: H01H 3/26 (20060101);