WO2004044722A1

WO2004044722A1 - Hot pluggable drive detection

Info

Publication number: WO2004044722A1
Application number: PCT/US2003/001512
Authority: WO
Inventors: Vic Sangveraphunsiri; Felix Pinai; David Christensen
Original assignee: First Internet Alliance
Priority date: 2002-11-05
Filing date: 2003-01-17
Publication date: 2004-05-27
Also published as: AU2003301932A1

Abstract

The inventive subject matter is directed toward systems and methods in which signals indicative of a disk drive (160) presence are communicated over at least one of a serial communications port (140) and an SM bus (142).

Description

HOT PLUGGABLE DRIVE DETECTION

This application claims the benefit of U.S. provisional application number 60/424076 filed November 05, 2002, incorporated herein by reference in its entirety.

Field of The Invention The field of the invention is disk drive detection.

Background of The Invention

A multiple disk storage system is one in which an array of hard disk drives is managed by a controller to appear as a single drive. Multiple disk storage systems (e.g. a redundant array of independent disks or RAID configuration) have been found to possess many advantages over a single large disk drive. Among the advantages that multiple disk systems have over a single disk system are the conservation of power, increased retrieval speed due to less distance for an actuator to travel, increased security of data, greater flexibility to add and remove disks, higher data availability, and lower cost per megabyte.

h a single disk system, the failure of the single drive generally takes the system down until the drive is replaced. Even with a replacement drive installed, the data existing on the bad drive must be loaded to the replacement drive. The result is both time consuming and laborious. In a multiple disk system, redundant data is stored so that when a drive is lost, the impact is minimal. Redundant data may be stored by using a mirroring technique or by parity redundancy, h either case, the ability to replace a disk without bringing the system down (i.e. a hot pluggable technology) is valuable in terms of minimizing time lost and labor needed to recreate data.

Essential to the concept of a hot pluggable device is the detection of the presence or absence of a drive. Generally, drives are queried for their presence using communications that traverse over a system I/O bus (e.g. PCI or peripheral component interconnect) to a hard disk interface (e.g. SCSI or IDE/ AT A). However, such methods of detecting presence are complicated because both control and content data are communicated over the bus. There is a need for simplified systems and methods in which control data is communicated via a separate channel from content data.

Summary of the Invention

The present invention is directed to devices and methods in which a control signal indicative of a drive problem is communicated over a serial communications cable. It is advantageous to use com port 2 on the motherboard to receive such control signals. In another aspect, an SM bus (system management bus, also referred to as SMBus) will be used for communication of control signals and within this type of configuration a 24 wife ribbon cable will be utilized. Methods of detecting a disk drive can include the steps of receiving a control signal at either a serial communications port or at an SM bus, then using a series of steps to determine whether the drive is present.

Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.

Brief Description of The Drawings

Fig. 1 is a schematic of a system in which control signals are communicated using a serial port.

Fig. 2 is a perspective view of a drive tray.

Fig. 3 is a schematic of a system in which control signals are communicated using an

SM bus.

Fig. 4 is a block diagram of a method of detecting drive presence.

Detailed Description

Referring first to Fig. 1, a system 100 for detecting a disk drive in a multiple disk drive array generally includes a motherboard 110, ribbon cables 120, baclφlane 125, disk drive connectors 130, a serial communications port 140, a serial cable 142, disk drives 160, and disk trays 170.

The multiple disk array of Fig. 1 comprises 4 disk drives 160 on 4 disk trays 170 although that number can vary from as few as two drives to as many as 8 or more drives. A multiple disk array can be a RAID configuration or can be some other form of distributed storage such including those that utilize mirroring and those that do disk spanning. A disk drive 160 is preferably an IDE (intelligent drive electronics) type drive having rotating storage media, but can be any type of storage device including those that use non-rotating media (e.g. an optical drive). A preferred drive is a 3.5 inch size (e.g. 3.5 x 1 x 5.25). Advantageously configured disk drives typically have integrated logic controllers and likely utilize an IDE/ATA (advanced technology attachment) or SCSI (small computer system interface) hard drive interface. Other appropriate interfaces include a parallel port interface, PCMCIA, USB, Firewire, Fiber Channel, USB 2.0 and Serial ATA.

Motherboard 110 is the main circuit board of a computer. A preferred motherboard contains the connectors for attaching additional boards as well as a CPU, Bios, ports, peripheral controllers, expansion slots, and so on. The motherboard 110 supports the serial communications port 140 that receives control signals (not shown) communicated through the serial cable 142. With respect to receipt of control signals, it should be understood that in some embodiments, control signals may be received by an SM bus rather than a serial port and these embodiments will be explored in more detail with reference to Fig. 2.

A ribbon cable 120 exists for each of the four disk drives 160 depicted in Fig. 1. Ribbon cables are flat cables having wires side by side, h this case, a 40 conductor ribbon cable is utilized which will also have a 40 pin connector. While other cable/connector combinations are contemplated, a standard IDE/ATA compatible cable and connector has 40 conductors and pins.

Turning now to the disk drive connectors 130, a preferred connector is an SCA-2 (single connector attachment) using 80 pins, a configuration which is frequently used with SCSI devices. The disk drive connectors 130 are generally components of the drive interface and provide channels for communication to and from the drives 160. With regard to the 80 pin connector, Table A shows the contemplated pin arrangement. Attention should be drawn to pin 45 which indicates a drive presence.

Drive trays 170 support the drives 160 and comprise interface electronics. The size and components of a preferred drive tray are depicted in Fig. 2. Drive tray 200 has an area for the drive 210, an interface circuit board 220, and plastic handle 230 that cooperates with a pivot point 232 and a handle release button 234 when inserting and removing a drive tray 200. Drive tray 200 is 4.25" wide at its maximum width allowing for up to 4 trays to be used in a standard 17" rack. In certain embodiments, it is required that the distance from a pivot point on the tray to the SCA (or other) connector is approximately 7.025". While the previously enumerated sizes are not always required, they are exemplary of a preferred class of embodiments.

Returning to Fig. 1, a serial communications port 140 has 10 conductors 142 and associated pins. Table B shows the contemplated pin arrangement with reference to the modem control signals that are typically communicated over the particular pin. For example, pin 1 which when used with a modem represents a DCD (data carrier detect) is used to detect drive 2. It should be noted that drive detection is merely an indication that a drive is present or absent, and is not conclusive of the existence or absence of a drive. Additional evaluation is generally required to determine whether a signal equates to a drive problem or drive absence. In any case, a path of communication from the disk drive 160 traverses the connector 130, the backplane 125 and the serial cable 142 to the motherboard 110.

In Fig. 3, a system 300 using an SM bus 315 includes a motherboard 310, a primary backplane 320 supporting 4 disk drives and a secondary backplane 330 supporting 4 disk drives. The primary and secondary backplanes are interconnected using a ribbon cable 325. In the depicted configuration the SM bus 315 carries indications of drive present for each of the 8 drives (4 on the primary baclφlane and 4 on the secondary baclφlane). h a further aspect, hardware status (i.e. fans, board ID LED, and power supply status) is communicated to the front panel of a computing device.

SM bus 315 is a communications channel that utilizes 2 pins of cable (i.e. a 24 pin ribbon cable) and associated connectors to transmit information including an indication of drive presence. The 24 conductor cable carries the signals for the power switch as well as the SM bus and generally follows an I2C (Inter Integrated Circuit Bus) protocol. In certain embodiments, two I2C devices are connected to the SM bus. The first device is an 8 bit I/O expander (e.g. a Philips PCF8574, Intel P1TX4, and Winbond 82C601) and the second device is a hardware monitor chip (e.g. a National LM87).

Fig. 4 exemplifies a method of detecting drive presence which begins with receipt of signals at a serial communications port. The signals generally indicate whether a drive is malfunctioning or absent (i.e. not physically connected), h order to determine whether the drive is actually absent, the steps 10-40 specified in Fig. 4 can be performed. It should be appreciated that in checking a drive status, if the result shows that the drive is present, further steps are likely not necessary. However, if in checking the drive status the drive presence is not conclusive, it may become necessary to perform step 50 - a readwrite test of sector count.

Thus, specific embodiments and applications of hot pluggable drive detection have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "comprises" and "comprising" should be inteφreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

Claims

CLAIMSWhat is claimed is:

1. A system for detecting a disk drive in a multiple disk drive array, comprising: a serial communication port that receives a control signal indicative of a presence of the drive.

2. The system of claim 1, further comprising a connector having a pin that through which the control signal is communicated.

3. The system of claim 2, wherein the connector is a ten pin connector that detects the presence of at least 4 disk drives of the multiple disk drive array.

4. The system of claim 1 , wherein the serial communication port is identified as COM2 on the motherboard.

5. The system of claim 1, wherein the control signal is associated with a DSR modem control signal.

6. The system of claim 1, wherein the control signal is associated with a CTS modem control signal.

7. The system of claim 1, wherein the disk drive is coupled to a backplane using an 80 pin connector.

8. The system of claim 7, wherein the 80 pin connector is a standard SCA-2 connector.

9. The system of claim 1, further comprising a drive tray that houses the disk drive.

10. The system of claim 9, wherein the drive tray comprises an interface PCB that cooperates with the 80 pin connector to communicate data to the backplane.

11. The system of claim 7, wherein the baclφlane further comprises a 40 pin connector that is used to communicate data from the backplane to a system board.

12. The system of claim 11, wherein the 40 pin connector is a standard IDE connector.

13. The system of claim 12, wherein the disk drive comprises an IDE interface.

14. The system of claim 1, further comprising a set of instructions that provides additional indications of drive presence.

15. A system for detecting a disk drive in a multiple disk environment, comprising: an SM (system management) bus that receives a control signal indicative of a presence of the disk drive.

16. The system of claim 15, further comprising a set of instructions that programatically checks the status of the disk drive.

17. A method of detecting a disk drive in a multiple disk environment, comprising: receiving a control signal at either a serial communications port or a system management bus; and intei-preting the control signal into a drive present signal.

18. The method of claim 17, wherein the drive present signal is received by the serial communications port.

19. The method of claim 17, wherein the drive present signal is received by the SM bus.

20. The method of claim 17, further comprising the step of communicating the drive present signal from the disk drive to a backplane using an 80 pin cable.