Local access of a remotely mirrored disk in a computer network

Details Local access of a remotely mirrored disk in a computer network Local access of a remotely mirrored disk in a computer network

2000-07-03

2002-11-19

Burgess, Glenton B. (Department: 2153)

Electrical computers and digital processing systems: multicomput

Computer-to-computer data routing

Reexamination Certificate

active

06484208

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to computer networks having mirrored or phantom disk resources, and more particularly to a mechanism for allowing disk I/O to take place between matching remote disk mirror drivers on a computer network.
The Windows NT operating system is described in detail in a set of five volumes entitled “Microsoft Windows NT Resource Kit—for Windows NT Workstation and Windows NT Server Version 3.51, Technical Reference Set” published by Microsoft Press, 1994. The five volumes include “Windows NT Messages,” Windows NT Networking Guide,” and “Windows NT Resource Guide.” Reference is also made to M. Minasi et al., “Mastering Windows NT Server 3.51,” 2nd Ed., published by Network Press, copyright by Sybex, Inc., 1996, and K. Siyan, “Windows NT Server—Professional Reference,” New Riders Publishing, 1995. All of these publications are incorporated herein by reference. This Windows NT operating system includes facility for supporting a computer network in which resources on various nodes of a network can be accessed from any other node. For example, a disk storage resource on a first node can be accessed, as if it were local, by another node which may be far removed from the first node.
A function that is needed in some systems is that of disk mirroring or phantom disk access. Mirroring usually means that the contents of one disk are duplicated on another disk, i.e., every write to disk is mirrored on another disk, so redundancy is provided. In case of failure of one of the disks, the system can continue operating without hesitation. A degree of fault tolerance is thus provided. In the context of this application, mirroring can mean also that a disk resource physically located on a first node may be accessed transparently by another node, just as if the access was through the first node. This may also be referred to as phantom disk operation, or as “clustering” of disks. In any event, a function such as mirroring or phantom disk access as described here is not facilitated by the Windows NT operating system.
It has been the practice to configure a network operating system such as Windows NT in such a manner that servers can share disk drives over a local area network. However, there is no arrangement whereby disk drives on one machine can be made to appear as if they were physically located on another machine. The disk I/O requests available in Windows NT are made up or defined by so-called Major Function Code routines, and it is these routines which must be used in any efficient and compatible functionality of disk mirroring.
SUMMARY OF THE INVENTION
It is therefore one object of the present invention to provide an improved method of mirroring network resources such as disk drives on a computer network.
A further object of the invention is to provide a mechanism for allowing disk drives on one machine to appear as if they were physically located on another machine, particularly in a Windows NT network environment, and using standard Windows NT Major Function Code routines.
It is another object of the present invention to provide an improved mechanism for disk I/O to take place between matching remote disk mirror drivers.
It is yet another object of the present invention to provide a method and apparatus for accessing a remote disk through nodes on a network which mirror the disk, employing packet communication between the access node and remote node which is compatible with operating systems such as Windows NT or the like.
The above as well as additional objects, features, and advantages of the present invention will become apparent in the following detailed written description.
According to one embodiment of the invention, a mechanism is provided where disk I/O can take place between matching remote disk mirror drivers on a network (e.g., a LAN or local area network). A computer network has a number of nodes which interact with one another via messages using a network protocol, and a node may access various network resources such a remote disk drives as if they were local. A disk drive is mirrored so that it may be accessed via one node when the drive is actually located at another node. This mirroring is transparent to the node which originates a disk request. A high-speed communications path is provided between the node which actually has the disk resource and the node from which the disk drive is mirrored. This communications path is usually separate from the primary or “public” network path (i.e., the LAN). On the communications path between the two nodes, a packet protocol is used which conveys a minimum but adequate amount of information needed to satisfy the requirements for disk I/O to take place between matching remote disk mirror drivers on the two nodes. The packet structure minimizes the need for creating new storage objects and saving them in implementing the mirroring functions. This packet identifies the remote drive and the function to be performed, has a field for status of a request packet, defines the length of the data field, and conveys the data, if any. The same packet is used for requests and returns. It contains values used to facilitate data flow instead of pointers and structures to queues. In a preferred embodiment, the packet is optimized for use with Windows NT structures, minimizing data copies.


REFERENCES:
patent: 4534024 (1985-08-01), Maxemchuk et al.
patent: 5001628 (1991-03-01), Johnson et al.
patent: 5157663 (1992-10-01), Major et al.
patent: 5237693 (1993-08-01), Kiyohara et al.
patent: 5390316 (1995-02-01), Cramer et al.
patent: 5463381 (1995-10-01), Ryu et al.
patent: 5469549 (1995-11-01), Simpson et al.
patent: 5633999 (1997-05-01), Clowes et al.
patent: 5668943 (1997-09-01), Attanasio
patent: 5673384 (1997-09-01), Hepner et al.
patent: 5721906 (1998-02-01), Siefert
patent: 5757642 (1998-05-01), Jones

Affiliated with

Also associated with

Rating

Local access of a remotely mirrored disk in a computer network does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Local access of a remotely mirrored disk in a computer network, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Local access of a remotely mirrored disk in a computer network will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2937865