Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique
Reexamination Certificate
1999-06-30
2003-09-30
Kim, Matthew (Department: 2186)
Electrical computers and digital processing systems: memory
Storage accessing and control
Control technique
C370S357000
Reexamination Certificate
active
06629216
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to data storage systems and more particularly to data storage systems having a plurality of magnetic storage disk drives in a redundancy arrangement whereby the disk drives are controllable by first disk controllers and second disk controllers. Still more particularly, the invention also relates to systems of such type wherein the disk drives are coupled to the disk controllers through a series, unidirectional, “ring” or, fibre channel protocol, communication system.
As is known in the art, in one type of data storage system, data is stored in a bank of magnetic storage disk drives. The disk drives, and their coupled interfaces, are arranged in sets, each set being controlled by a first disk controller and a second disk controller. More particularly, in order to enable the set of disk drives to operate in the event that there is a failure of the first disk controller, each set is also coupled to a second, or redundant disk controller. Therefore, if either the first or second disk controller fails, the set can be accessed by the other one of the disk controllers.
While today, most disk storage systems of this type use a Small Computer System Interconnection (SCSI) protocol, in order to operate with higher data rates, other protocols are being introduced. One higher data rate protocol is sometimes referred to as a fibre channel (FC) protocol. Such FC channel protocol uses a series, unidirectional, “ring” communication system. In order to provide for redundancy, that is, to enable use of the set of disk drives in the event that the first disk controller fails, as discussed above, the set is coupled to the second, or redundant disk controller, using a separate, independent, “ring”, or fibre channel communication protocol. Thus, two fibre channels are provided for each set of disk drives and their disk interfaces; a first fibre channel and a second fibre channel.
As is also known, when using the fibre channel communication protocol, if any element in the channel becomes inoperative, the entire channel becomes inoperative. That is, if the first disk controller becomes inoperative, or if any one of the disk drives in the set coupled to the first channel becomes inoperative (i.e., as where the disk interface fails, the disk interface is inoperative, or removed with its coupled disk drive, or where the disk drive coupled thereto fails, or is removed), the first fibre channel, is “broken”, or open, and becomes inoperative. The data stored in the entire portion of the set of disk drives coupled to the first disk channel is therefore unavailable until the inoperative first disk controller or inoperative disk drive is replaced. This is true with either the first channel or the second channel. One technique suggested to solve this problem is through the use of a switch, sometimes referred to as an LRC (i.e., a loop resiliency circuit) switch. Such LRC switch is used to remove an inoperative disk drive from its channel.
In one suggested arrangement, a printed circuit board is provided for each disk drive. The printed circuit board has a pair of LRCs, one for the first channel and one for the second channel. Thus, the open channel may be “closed” in the event of an inoperative disk drive by placing the LRC thereof in a by-pass condition. While such suggested technique solves the inoperative disk drive, or open channel problem, if one of the pair of LRCs fails, the entire printed circuit board having the pair of LRCs must be replaced thereby disrupting both the first and second channels; and, hence, disrupting the operation of the entire data storage system.
One technique suggested to solve this disruption problem requires n LRC switches (where n is the number of disk drives in the set) in the first channel, i.e., one LRC for each one the n disk drives in the set and another n LRC switches in the second channel for each one of the n disk drives in the second channel. The first channel set of n LRCs is mounted on one printed circuit board and the second channel set of n LRCs is mounted on a different printed circuit board. A backplane is used to interconnect the two LRC printed circuit boards, the associated multiplexers, and the disk drives. In order to provide the requisite serial, or sequential, fibre channel connections, an elaborate, complex, fan-out wiring arrangement has been suggested for the backplane. Further, the slots provided for the two LRC boards eliminates two disk drives, and the disk interfaces which would otherwise be plugged into these two slots of the backplane.
Another fibre channel arrangement is described in U.S. Pat. No. 5,729,763 entitled “Data Storage System”, inventor Eli Leshem, issued Mar. 17, 1998, assigned to the same assignee as the present invention.
SUMMARY OF THE INVENTION
In accordance with one feature of the invention, a data storage system is provided having a plurality of disk drives. Each one has a pair of ports. A pair of directors is included for controlling the flow of information (i.e, data) to and from the disk drives. A first fibre channel port by-pass selector section is provided. The first fibre channel selector section includes: an input/output port coupled to a first one of the directors; and, a plurality of output/input ports connected between a first one of the ports of the plurality of disk drives through a first plurality of fibre channel links. The first fibre channel port by-pass selector section is adapted to couple the first one of the directors serially to one, or ones, of the first ports of the plurality of disk drives through a first fibre channel selectively in accordance with a control signal fed to the first fibre channel by-pass selector. The first fibre channel includes one, or more, of the first plurality of fibre channel links. A second fibre channel port by-pass selector section is provided having an input/output port coupled to a second one of the directors and a plurality of output/ports serially connected between a second one of the pair of ports of the plurality of disk drives through a second plurality of fibre channel links. The second fibre channel port by-pass selector section is adapted to couple the second one of the directors serially to one, or ones, of the second ports of the plurality of disk drives through a second fibre channel selectively in accordance with the control signal. The second fibre channel includes one, or more, of the second plurality of fibre channel links.
REFERENCES:
patent: 5206939 (1993-04-01), Yanai et al.
patent: 5212785 (1993-05-01), Powers et al.
patent: 5729763 (1998-03-01), Leshem
patent: 5890214 (1999-03-01), Espy et al.
patent: 5898828 (1999-04-01), Pignolet et al.
patent: 5922077 (1999-07-01), Espy et al.
patent: 5991891 (1999-11-01), Hahn et al.
patent: 6038618 (2000-03-01), Beer et al.
patent: 6061753 (2000-05-01), Ericson
patent: 6118776 (2000-09-01), Berman
patent: 6138199 (2000-10-01), Fleischer
patent: 6154791 (2000-11-01), Kimble et al.
patent: 6185203 (2001-02-01), Berman
patent: 6192027 (2001-02-01), El-Batal
patent: 6195703 (2001-02-01), Blumenau et al.
patent: 6219753 (2001-04-01), Richardson
patent: 6260079 (2001-07-01), White
patent: 6282169 (2001-08-01), Kiremidjian
patent: 6338110 (2002-01-01), van Cruyningen
patent: 6389494 (2002-05-01), Walton et al.
patent: 2002/0012342 (2002-01-01), Oldfield et al.
patent: 0 550 853 (1993-07-01), None
patent: 0 751 464 (1997-01-01), None
patent: 0 889 410 (1999-07-01), None
patent: WO 97/07458 (1997-02-01), None
patent: WO 98/28882 (1998-02-01), None
patent: WO 99/26146 (1999-05-01), None
Kimble, “In-depth fibre channel arbitrated loop”, Ch. 2, Port bypass circuit (pp. 42-43); Ch. 15, High-availability loops (pp. 269-282) (Solution Technology, copyright 1996, 1997).*
Co-Pending U.S. application No. 09/224,194, filed Dec. 30, 1998.
Co-Pending U.S. application No. 09/345,048, filed Jun. 30, 1999, Fibre channel data storage system having expansion/contraction
Co-Pending U.S. application No. 09/345,053, filed Jun. 30, 1999, Fibre channel port by-pass selectgor sections fo
Linnell Thomas Earl
Mulvey Christopher J.
Tuccio William R.
Bataille Pierre-Michel
Daly, Crowley & Mofford LLP
EMC Corporation
Kim Matthew
LandOfFree
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