Electrical computers and digital data processing systems: input/ – Input/output data processing – Peripheral monitoring
Reexamination Certificate
1998-12-30
2002-01-22
Shin, Christopher B. (Department: 2782)
Electrical computers and digital data processing systems: input/
Input/output data processing
Peripheral monitoring
C710S033000, C710S111000
Reexamination Certificate
active
06341317
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a method and apparatus for managing a log of information in a computer system including an intelligent storage system.
DESCRIPTION OF THE RELATED ART
Many computer systems include one or more host computers and one or more storage systems that store data used by the host computers. An example of such a system is shown in
FIG. 1
, and includes a host computer
1
and a storage system
3
. The storage system typically includes a plurality of storage devices on which data is stored. In the exemplary system shown in
FIG. 1
, the storage system includes a plurality of disk drives
5
a
-
5
b,
and a plurality of disk controllers
7
a
-
7
b
that respectively control access to the disk drives
5
a
and
5
b.
The storage system
3
further includes a plurality of storage bus directors
9
that control communication with the host computer
1
over communication buses
17
. The storage system
3
further includes a cache
11
to provide improved storage system performance. In particular, when the host computer
1
executes a read from the storage system
3
, the storage system
3
may service the read from the cache
11
(when the data is stored in the cache), rather than from one of the disk drives
5
a
-
5
b,
to execute the read more efficiently. Similarly, when the host computer
1
executes a write to the storage system
3
, the corresponding storage bus director
9
can execute the write to the cache
11
. Thereafter, the write can be destaged asynchronously, in a manner transparent to the host computer
1
, to the appropriate one of the disk drives
5
a
-
5
b.
Finally, the storage system
3
includes an internal bus
13
over which the storage bus directors
9
, disk controllers
7
a
-
7
b
and the cache
11
communicate.
The host computer
1
includes a processor
16
and one or more host bus adapters
15
that each controls communication between the processor
16
and the storage system
3
via a corresponding one of the communication buses
17
. It should be appreciated that rather than a single processor
16
, the host computer
1
can include multiple processors. Each bus
17
can be any of a number of different types of communication links, with the host bus adapter
15
and the storage bus directors
9
being adapted to communicate using an appropriate protocol for the communication bus
17
coupled therebetween. For example, each of the communication buses
17
can be implemented as a SCSI bus, with the directors
9
and adapters
15
each including a SCSI driver. Alternatively, communication between the host computer
1
and the storage system
3
can be performed over a Fibre Channel fabric that implements the communication bus
17
.
As shown in the exemplary system of
FIG. 1
, some computer systems employ multiple paths A-D for communicating between the host computer
1
and the storage system
3
(e.g., each path includes a host bus adapter
15
, a bus
17
and a storage bus director
9
in FIG.
1
). In many such systems, each of the host bus adapters
15
has the ability to access each of the disk drives
5
a
-
5
b,
through the appropriate storage bus director
9
and disk controller
7
a-b.
The storage system
3
disclosed in
FIG. 1
is an intelligent storage system that controls the location wherein data accessible via the host computer
1
is stored. Thus, the exact physical location (i.e., which one of the disk drives
5
a
-
5
b
and the location on the disk drive) wherein any block of data is actually stored is transparent to the host computer
1
. In this respect, a computer system such as that shown in
FIG. 1
typically includes a plurality of layers as shown in FIG.
2
. The layers include an application layer
21
that resides on the host computer
1
and references data objects (e.g., files) used by the application. In addition, the host computer
1
also includes a file system and/or logical volume manager layer
23
that maps each data object specified by the application layer
21
to a particular logical volume, that the host computer
1
perceives to correspond to an actual physical storage device, wherein the data object is stored. Thus, if the computer system included a storage system without any intelligence, the logical volumes specified by the file system/LVM layer
23
would designate a particular physical device and a particular storage location thereon wherein the data object would be stored. Finally, the computer system further includes a storage system mapping layer
25
that resides on the storage system, and that maps from the logical volume provided from layer
23
to an actual physical location, including at least one of the disk drives
5
a
-
5
b
and the physical location thereon, wherein the logical volume is stored. The mapping between a logical volume and a physical disk drive may not be 1:1, as a single logical volume can be split across multiple physical disk drives
5
a
-
5
b,
or alternatively, multiple logical volumes can be stored on the same physical disk drive.
It is an object of the present invention to provide an improved method and apparatus for managing the placement of data on a storage system to achieve improved system performance.
SUMMARY OF THE INVENTION
One illustrative embodiment of the invention is directed to a method of managing a log of information in a computer system including a host computer and an intelligent storage system that is coupled to the host computer and stores data accessed by the host computer, the computer system including a plurality of logical volumes of data that are visible to the host computer and the storage system and that are perceived by the host computer as comprising a plurality of raw storage devices, the storage system including at least one physical storage device and at least one mapping layer that maps the plurality of logical volumes to the at least one physical storage device. The method comprises a step of creating the log to include information concerning at least one input/output (I/O) operation passed from the host computer to the intelligent storage system, the information including a first component of information relating to aspects of the at least one I/O operation controlled by the host computer and a second component of information relating to aspects of the at least one I/O operation controlled by the intelligent storage system.
Another illustrative embodiment of the invention is directed to a computer readable medium encoded with a program for execution on a computer system including a host computer and an intelligent storage system that is coupled to the host computer and stores data accessed by the host computer, the computer system further including a plurality of logical volumes of data that are visible to the host computer and the intelligent storage system and that are perceived by the host computer as comprising a plurality of raw storage devices, the storage system including at least one physical storage device and at least one mapping layer that maps the plurality of logical volumes to the at least one physical storage device. The program, when executed on the computer system, performs a method of managing a log of information in the computer system, the method comprising a step of creating the log to include information concerning at least one input/output (I/O) operation passed from the host computer to the intelligent storage system, the information including a first component of information relating to aspects of the at least one I/O operation controlled by the host computer and a second component of information relating to aspects of the at least one I/O operation controlled by the intelligent storage system.
A further illustrative embodiment of the invention is directed to a host computer for use in a computer system including the host computer and an intelligent storage system that is coupled to the host computer and stores data accessed by the host computer, the computer system including a plurality of logical volumes of data that are visible to the host computer and the storage s
Blumenau Steven M.
D'Errico Matthew J.
Ofer Erez
EMC Corporation
Shin Christopher B.
Wolf Greenfield & Sacks P.C.
LandOfFree
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