U.S. patent application number 11/976484 was filed with the patent office on 2008-03-13 for data storage system and control method thereof.
Invention is credited to Hiroshi Morishima, Tatsuya Murakami, Yasuaki Nakamura, Toshio Nakano, Akinobu Shimada.
Application Number | 20080065850 11/976484 |
Document ID | / |
Family ID | 19116840 |
Filed Date | 2008-03-13 |
United States Patent
Application |
20080065850 |
Kind Code |
A1 |
Nakamura; Yasuaki ; et
al. |
March 13, 2008 |
Data storage system and control method thereof
Abstract
In the configuration of multiple (M units of) disk subsystems
shared from multiple (N units of) hosts, having an exclusive
control command that limits access to all disk subsystems
temporarily is provided, using this exclusive control command,
configuration information of all multiple disk subsystems, for
example, performance and a setting change, are acquired in point of
time series and stored in a management server database
("configuration information database"), then managed in a
centralized manner, a function that associates the file that the
application uses with the "configuration information database" is
provided using a function that detects the position on the logical
unit, and a means that can retrieve the modified contents of the
system configuration and time as keys is provided in the
"configuration information database".
Inventors: |
Nakamura; Yasuaki;
(Fujisawa, JP) ; Nakano; Toshio; (Chigasaki,
JP) ; Shimada; Akinobu; (Chigasaki, JP) ;
Murakami; Tatsuya; (Odawara, JP) ; Morishima;
Hiroshi; (Yokohama, JP) |
Correspondence
Address: |
MATTINGLY, STANGER, MALUR & BRUNDIDGE, P.C.
1800 DIAGONAL ROAD
SUITE 370
ALEXANDRIA
VA
22314
US
|
Family ID: |
19116840 |
Appl. No.: |
11/976484 |
Filed: |
October 25, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10077966 |
Feb 20, 2002 |
7305462 |
|
|
11976484 |
Oct 25, 2007 |
|
|
|
Current U.S.
Class: |
711/163 ;
711/E12.001 |
Current CPC
Class: |
H04L 69/329 20130101;
H04L 67/1097 20130101; H04L 41/0843 20130101; H04L 41/0853
20130101; G06F 3/0605 20130101; G06F 3/067 20130101; G06F 3/0637
20130101 |
Class at
Publication: |
711/163 ;
711/E12.001 |
International
Class: |
G06F 12/00 20060101
G06F012/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2001 |
JP |
2001-295397 |
Claims
1. A control method of a data storage system in which multiple
external storage systems that store information are connected to a
first network and each of said multiple external storage systems is
arranged separately, comprising: generating an interrupt by an
external storage system to a management server; and issuing an
exclusive control command by said management server to said
external storage system; wherein said exclusive control command
temporarily limits access to said external storage system such that
said management server is the only control server that enables
configuration setting of the data storage system; wherein said
management server acquires configuration information of said
external storage systems in point of time series and stores said
configuration information in the database managed by said
management server using said exclusive control command, and wherein
a time series acquisition is made with a simultaneous and periodic
inquiry into multiple external storage systems as moments.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation application of U.S. patent
application Ser. No. 10/077,966, filed on Feb. 20, 2002, now
allowed, the contents of which are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a centralized management
art of a data storage system (hereinafter merely referred to as a
storage system) when multiple computers that use information and
multiple external storage systems (hereinafter referred to as disk
subsystems) that store information are connected to a network and
arranged separately, and more particularly to a management art of
the whole storage system that extends over the multiple disk
subsystems.
BACKGROUND OF THE INVENTION
[0003] In order to perform centralized management of data extending
over multiple external storage systems, for example, multiple disk
subsystems, the configuration information of each system is
acquired and the whole configuration in which the whole system was
integrated needs to be defined. Here, the configuration
information, includes, for example, setting concerning an internal
access path of a disk subsystem, a logical unit, the capacity or
access authority of the logical unit and data move, setting
concerning data copying between the disk subsystems, setting or
acquisition of a performance control mode or performance data,
setting of a maintenance method and a fault or user operation
event.
[0004] In the past, system administrators periodically collected
the configuration or performance of a disk subsystem, fault,
expansion and other events (hereinafter referred to as events) that
will occur under the system using software that a host computer
(hereinafter merely referred to as a host) which uses the disk
subsystem manages. That is, a system administrator had to connect
the host computer to each disk subsystem and acquire the
configuration information of these systems, then provide the
definition and necessary setting of the whole system configuration
using management software by manual operation.
[0005] An art for displaying in mapping mode that a logical volume
that can access a disk subsystem from a host corresponds to which
physical unit of the disk subsystem is disclosed in U.S. Pat. No.
5,973,690. However, there is no suggestion concerning transverse
management between multiple disk subsystems.
[0006] In order to define the whole configuration in which the
whole system was integrated, desirably, a system administrator
should collectively perform setting that extends over between the
multiple disk subsystems. This is because the configuration of the
whole system is defined more easily than it is defined every disk
subsystems and the number of times the configuration is checked and
redefined is reduced, thereby reducing artificial misoperation.
This is because the system operation can also be improved if the
setting that extends over between the multiple disk subsystems is
performed collectively.
[0007] The state is considered in which a certain user A installs a
database and another application A in a host computer and multiple
disk subsystems are used as an external storage system. Because the
size of the file that the application A of the user A uses was
reduced, a system administrator S of this external storage system
is assumed to have added a logical unit (LU) to a disk
subsystem.
[0008] However, the disk subsystem may also use another application
B (higher performance than for the application A is requested) that
the user B uses in another host.
[0009] In such case as this, if the added logical unit should have
shared a physical resource (physical unit) with a logical unit
allocated so that the application B that requests high performance
can use it, the addition of this logical unit is affected and
performance degradation will be caused concerning the execution of
the applications in which importance is attached to the
performance.
[0010] In other words, although the addition of the logical unit
that the system administrator S made and that was made for the user
A is a measure for maintaining and increasing the execution of the
application A of the user A, the measure will cause degradation of
the execution performance of the application B, and is eventually
said to be artificial misoperation when it is viewed from the
performance aspect of the whole system.
[0011] A system administrator normally monitors the performance of
an application using a performance monitoring tool. Because the
performance monitoring tool monitors the process operating state of
the application or the read and write performance of the file that
the application uses, a cause in which the addition of the previous
logical unit gave rise to the performance degradation of another
application cannot be ascertained.
[0012] With the sudden spread of the Internet, access requests from
many client terminals increase. These access requests are regarded
as access from multiple hosts. A storage system that integrates
these many types of access also requires a measure that follows the
demand of data size, and the opportunity of logical unit expansion
in an individual disk subsystem is increasing constantly. It is
desired to predict when the logical unit that corresponds to the
file that a business-related application uses exceeds a usable
capacity and arrange a schedule of planned logical unit expansion.
Accordingly, an increasing tendency toward the file size, the
position of the logical unit in which the file was stored and the
usable capacity are investigated, and the schedule must be arranged
from these relationships.
[0013] In the prior art, although these pieces of information were
collected individually and periodically, there is no means for
building these relationships. The measure is no more than a measure
that depends on an empirical rule of a system administrator, and
the above prediction and planning were very difficult.
SUMMARY OF THE INVENTION
[0014] One object of the present invention is to provide a
management art for allowing multiple system administrators (L
persons) to manage multiple (M units of) disk subsystems
transversely and collectively and realize predetermined setting
quickly and simply in the configuration of the multiple (M units
of) disk subsystems shared from multiple (N units of) hosts.
[0015] Another object of the present invention is to provide a
management art of a disk subsystem by which an influence that the
configuration modification of the disk subsystem has on the
performance of the application executed by a host can be
grasped.
[0016] A further object of the present invention is to provide a
management art by which the additional time of the planned logical
unit capacity in a disk subsystem can be determined.
[0017] The present invention has been made in view of the above
circumstances and provides a data storage system and a control
method thereof having following features.
[0018] 1) An exclusive control command that temporarily limits
access to all multiple disk subsystems is provided.
[0019] 2) Using this exclusive control command, the configuration
information of all multiple disk subsystems, for example,
performance or a setting change, is acquired in point of time
series and stores it in a database ("configuration information
database") of a management server part, then manages it in a
centralized manner.
[0020] 3) A function of associating the file that an application
uses with the "configuration information database" is provided
using a function of detecting the position of the file on a logical
unit.
[0021] 4) A means that can retrieve the modified contents or time
of the system configuration as keys is provided in the
"configuration information database".
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Preferred embodiments of the present invention will be
described in detail based on the followings, wherein:
[0023] FIG. 1 is a drawing showing an outline of a system in which
multiple host computers are provided with multiple disk subsystems
that send and receive and share data via a network;
[0024] FIG. 2 is a drawing showing a functional block of a
management server to which the present invention is applied;
[0025] FIG. 3 is a drawing illustrating a flow of a procedure in
which desired setting that extends over multiple disk subsystems of
FIG. 2 are performed collectively;
[0026] FIG. 4 is an example of analysis made using the present
invention and a drawing showing a flow in which a history of
configuration information is traced and a cause of the performance
degradation of an application is investigated using the
configuration information database that the management server
possesses; and
[0027] FIG. 5 is an example of analysis made using the present
invention and a drawing showing a flow of analyzing the expansion
schedule of a logical unit using a history of file size possessed
by the management server.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] FIG. 1 shows a schematic configuration of the whole system
when multiple host computers 10 are connected to multiple disk
subsystems 20 that send and receive and share data via an SAN
(storage area network) 40. Each disk subsystem 20 is provided with
an external connection interface 21 for sending event information
in order to define and refer to its own configuration, show
performance and data and post a fault.
[0029] A management server part 30 is an interface of a local area
network (LAN) 50 that differs from the SAN 40 and can be connected
to the multiple hosts 10 and the multiple disk subsystems 20. In
FIG. 1, only the one management server 30 is shown, but the
multiple management servers can also be shown. Further, the
management server 30 can also be installed inside the disk
subsystems 20 and also be positioned at a place physically
separated from these disk subsystems 20. The technical term of a
"management server" includes a part of an external storage system
having a server function, and is appropriately described as a
"management server part".
[0030] It is considered that the configuration of the all multiple
disk subsystems 20 is defined collectively from a certain
management server part 30 extending over between these multiple
subsystems. The management server part is merely described as the
management server 30 below. An exclusive control command is issued
from the management server 30 to the systems 20 so that the
management server 30 will be the only one setting means. Here, the
exclusive control command indicates a command that occupies the
multiple disk subsystems 20 selected optionally in a time zone. The
occupancy time may also be about one hour when it is long. However,
setting information is created separately and a control method by
which setting is performed in a slight occupancy time is prepared.
The management server 30 has also a function of checking that the
setting terminates normally.
[0031] The functional block of the management server 30 is
described with reference to FIG. 2.
[0032] A user management layer 31 manages multiple users A to C
connected to the management server 30. Here, a system administrator
is included in a user.
[0033] An object management layer 32 manages acquisition of the
configuration information of each disk subsystem 20 and a setting
request from the user. The object management layer 32 has a
configuration information database 321.
[0034] An agent management layer 33 issues an exclusive control
command to each disk subsystem 20 via a subsystem interface 341 in
accordance with a request from the object management layer 32.
[0035] An interface layer 34 has the subsystem interface 341 that
performs data sending and receiving with each disk subsystem 20 and
a host interface 342 that controls access with each host agent
11.
[0036] While exclusive control is being performed, the object
management layer 32 acquires the configuration, performance and
fault and other event information of each disk subsystem 20 and
stores them in the configuration information database 321.
[0037] The only system administrator (user) whose access was
permitted by the user management layer 31 performs the change,
expansion, or deletion of parameters of the multiple disk
subsystems 20 stored in the configuration information database 321
extending over the same systems 20. As a result, the configuration
information database 321 and the configuration information of an
actual disk subsystem 20 can match without differing from each
other at a predetermined point of time.
[0038] The management server 30 releases all the occupied multiple
disk subsystems 20 by the agent management layer 33 when the
configuration modification, expansion and deletion of the systems
20 are completed by the object management layer 32 also including
the registration into its own configuration information
database.
[0039] Here, the information that is the configuration information
database 321 of the object management layer 32 and that the
management server 30 handles relates to the configuration
information about the setting concerning an internal access path of
each disk subsystem 20, a logical unit, these capacity and access
authority and data move, setting concerning data copying between
disk subsystems, setting of the performance or control of each disk
subsystem, acquisition of the performance data of each disk
subsystem, setting of a maintenance method and fault and user
operation events.
[0040] <Information Acquisition Timing>
[0041] The information acquisition timing of the disk subsystem 20
and the host 10 is before the configuration is instructed to the
system 20 when the only system administrator (user) accesses the
management server 30 and the management server 30 defines the
configuration of the system 20. On the other hand, the acquisition
timing is also established when the fault, maintenance and other
events of the disk subsystem 20 occurred. Specifically, the
acquisition timing is established in the following items.
[0042] 1) When the event is recognized and information is acquired
by the management server 30 through a periodic inquiry into each
disk subsystem 20.
[0043] 2) Further, when the fault and maintenance events that the
disk subsystem 20 detected were posted from the subsystem interface
341 (FIG. 2) to the agent management layer 33.
[0044] In the case of 2), the agent management layer 33 to which an
event, such as a fault, was posted posts the event to the object
management layer 32 of the upper layer using an interrupt function
and the management server 30 recognizes by the object management
layer 32 that received this event that the state of the disk
subsystem 20 was changed. After this event was recognized, the
management server 30 acquires the configuration information of the
system 20 and updates the information about the configuration
information database.
[0045] Besides, when the configuration of the disk subsystem 20 was
modified according to automatic expansion, fault and maintenance
events, the management server 30 specifies the modification and
registers it in its own configuration information database 321.
Here, if the flag is set in the disk subsystem 20 of the
configuration information database that the management server 30
possesses and the database is managed, the subsequent processing,
especially, the acquisition of information is performed efficiently
by making an inquiry into only the system 20 of which the flag is
on in the database.
[0046] <Information Acquisition Method>
[0047] An example of a procedure in which desired setting is
performed collectively extending over multiple disk subsystems
using the above method is described with reference to FIG. 3. This
procedure indicates that one of multiple system administrators
define these configurations against the multiple disk subsystems 20
(two units X and Y here). In this example, a function unique to a
disk subsystem that assigns an access authority from a host to a
logical unit and prevents invalid access to the logical unit, then
protects data is used.
[0048] Two disk subsystems 20 (X and Y) connected to the single
specific host 10 (FIG. 1) possess the predetermined number of
logical units. Under the environment where the multiple hosts 10
share the multiple disk subsystems 20, security needs to be set so
that the logical unit that the specific host 10 accesses cannot be
accessed from another host 10.
[0049] In FIG. 3, the system administrator S (user A) logs in the
management server 30 and requests access permission (step 311). On
receipt of this access permission, the management server 30 issues
an exclusive control command to the disk subsystems 20 (X and Y) so
that the management server 30 can become the only control server
that enables the configuration setting of the whole system (step
312).
[0050] The management server 30 acquires the configuration
information of each of the disk subsystems X and Y when the
exclusive control command is issued (step 313) and stores it in the
configuration information database 321 in FIG. 2.
[0051] The only system administrator S (user A) whose access to the
management server 30 was permitted makes a modification of the
system configuration collectively extending over the disk
subsystems X and Y (step 315) based on the configuration
information of the disk subsystems X and Y stored in the
configuration information database 321 (step 314).
[0052] Here, the modification of the configuration in this example
indicates that the system administrator S assigns an "access
authority from the specific host 10 to a predetermined logical
unit" to the specific host 10. Specifically, it indicates that a
unique address, for example, a WWN (World Wide Name) or MAC address
is allocated in a network assigned to the logical unit that the
host 10 under a port can access and a host bus adapter that the
host connected to the port is equipped with. Here, the port
indicates an input/output function used when the disk subsystem 20
sends and receives data to and from the host 10.
[0053] The management server 30 completes the modification of such
system configuration including the registration into its own
configuration information database (step 316) and releases the
occupied multiple disk subsystems X and Y (step 317).
[0054] While the disk subsystems X and Y are controlled exclusively
from the steps 312 to 317 of this example, even if another system
administrator T (user B) issues a setting request to the management
server 30 (step 318), the management server 30 posts to the system
administrator T that the system administrator S is being set.
[0055] The management server 30 further associates the host logical
configuration information with the configuration information of the
disk subsystems X and Y according to the following procedure. Here,
the host logical configuration information indicates the access
path information to a logical unit viewed from a file on an
operating system (herein after merely referred to as an OS),
position of the logical unit in which the file was stored, file
size, a database and each OS.
[0056] Besides, the access path to the logical unit viewed from
each OS can be specified using three items of a host adapter card
ID, a controller ID and a logical unit number, for example, if the
OS is a UNIX-system OS.
[0057] Such associating is performed to make a file accessed from
the host 10 and a logical unit inside the disk subsystem 20 that
stores this file correspond to each other by linking an ID that
indicates a physical area inside the system 20 and the information
of a device path used when a system administrator incorporates the
system 20 and to manage them collectively.
[0058] <Activation of Host Agent>
[0059] The multiple hosts 10 (FIG. 1) install the host agent 11 and
the host agent 11 is activated synchronizing with a subsequent
event in the following cases.
1) When the management server 30 modifies the configuration of the
disk subsystem 20 according to a request of a system administrator
and inquires each disk subsystem 20 of the acquisition of system
configuration information
[0060] 2) When the configuration of the disk subsystem 20 is
modified by fault, maintenance and other events, and the management
server 30 recognizes the status change of the disk subsystem 20 and
inquires each disk subsystem 20 of the acquisition of system
configuration information
[0061] The host agent 11 issues a command for identifying an access
path into the logical unit from its own host 10, to the logical
unit of the disk subsystem 20 to which its own host 10 can access
in order to acquire the "host logical configuration information" on
the OS of the host 10 that dominates the host agent.
[0062] The host agent 11 acquires the name and size of the file
stored inside the logical unit and the position on the file system
to which the file belongs using an OS, a database or an application
interface for high-level middleware.
[0063] The management server 30 collects the "host logical
configuration information" that each host agent 11 acquired and
associates it with an internal access path contained in the
configuration information of the disk subsystem 20, then stores it
in the configuration information database 321. A system
administrator can check the position of the logical unit in which
the file is stored by making an inquiry into the management
server.
[0064] The management server 30 collects the data of file size that
the host agent acquires and the application of the host 10 uses
synchronizing with a periodic inquiry into each disk subsystems 20
and accumulates it in the configuration information database 321 of
the management server 30 in point of time series.
[0065] The management server 30 similarly accumulates the contents
before and after the system configuration was modified in the
configuration information database of the management server 30 in
point of time series also when a system administrator modified the
configuration of the disk subsystem 20 and the configuration was
modified by the fault and maintenance events.
[0066] As a result, a system administrator can momentarily retrieve
the host logical configuration information and the modified
contents of the system configuration against the time series data
stored in the configuration information database of the management
server 30 as keys. Accordingly, an interrelationship when the
configuration of the disk subsystem 20 was modified with time
concerning the performance, file size and other parameters of the
disk subsystem can be found and analyzed.
SPECIFIC EXAMPLE 1 OF ANALYSIS
[0067] Specific examples are described below.
[0068] The first specific example is the case where a problem is
analyzed using the management server to which the present invention
applied when the following event occurred.
[0069] The case is considered where a certain user A uses a
database and another application in the host 10, and a system
administrator added a logical unit to the disk subsystem 20 that
uses the application to expand the file size. In this case, the
addition of a physical unit can also follow the addition of the
logical unit. However, the disk subsystem 20 may also use another
application B (higher performance than for the application A is
requested) that the user B uses in another host.
[0070] In such time as this, if the added logical unit should have
shared a physical resource (physical unit) with the logical unit
allocated so that the application B that requests high performance
can be used, the addition of this logical unit is affected and
performance degradation will be caused concerning the execution of
the application B in which importance is attached to the
performance. In the past, when a system administrator monitors the
performance of the application, an external performance monitoring
tool was used because monitoring cannot be performed from a
management server. This type of the tool monitors the process
operating state of the application and the read and write
performance from and to a file used. However, a cause that the
addition of such logical unit as above gave rise to the performance
degradation of the application could not be ascertained.
[0071] FIG. 4 shows a measure for which the system administrator S
can take using the management server 30 to which the present
invention applied (using the historical data of the configuration
information database 321 when the performance of the application
was degraded after a certain point of time.
[0072] The information that specifies a file that an application
uses and the time when the performance of the application was
degraded are input to the management server 30 (step 411). The
management server 30 that received the input specifies a physical
unit storage position indicating a logical unit that corresponds to
the file is positioned at which physical area in the disk subsystem
20, based on the data of the configuration information table 301 in
the configuration information database 321. Subsequently, another
logical unit that shares the physical unit is retrieved (step
412).
[0073] The contents of a setting change related to the physical
unit storage position are retrieved from the data in which a
history of the setting change, for example, the setting change
historical table 302 is accumulated before the time when the
performance of the application was degraded using this retrieval
result (step 413).
[0074] As to whether the setting change is related to the
performance degradation of an application or not, the management
server 30 checks that the performance of the logical volume is
degraded after the performance degradation time of the application,
referring to a performance historical table 303 that indicates the
performance history of a logical unit, for example (step 414). If
the performance is degraded, the fact (estimated cause or
additional time) that the relevant setting change is assumed to be
a cause is posted to the system administrator (step 415).
SPECIFIC EXAMPLE 2 OF ANALYSIS
[0075] The second specific example is the case where a problem is
analyzed using the management server 30 to which the present
invention applied when the following event occurred.
[0076] A system administrator periodically, for example, quarterly,
investigates an increasing tendency toward the file size that an
application uses, and arranges a schedule of the additional
capacity of the logical unit that the disk subsystem 20 retains
against this increasing tendency. On this occasion, the management
server supports planning according to the following procedure.
[0077] The management server 30 periodically inquires the host
agent 11 of the file size and accumulates the file size in a
database in point of time series. Subsequently, the management
server 30 retrieves associating with the logical unit in which the
file was stored from the contents of the configuration information
database 321. As shown in FIG. 5, based on the capacity (c4) of the
logical unit and the relationship between the file size accumulated
in point of time series and time, for example, the data of start
capacity (c1, t1) and the latest capacity (c2, t2), the time (t4)
when the file size is equal to the logical unit capacity limit (c4)
is predicted and is posted to a system administrator as the time
when the logical unit needs to be added, for example, additional
time.
[0078] A system administrator previously sets a file size
threshold, for example, user threshold (c3). When the file size
exceeded the user threshold (at t3), the system administrator is
warned against the fact that the addition of the logical unit will
be required in the near future.
[0079] Further, as the high-level application of the management
server 30, there is an application that manages the connection
modes of the host 10, switches (not shown) and the disk subsystem
20 those are the components of the SAN 40, and that manages the
information about each component in a centralized manner, and that
is provided with a function of performing fault monitoring and
performance display, then performs centralized management. This
high-level application can acquire the time series information and
history of the configuration and performance of each disk
subsystems 20 collectively by making an inquiry into the management
server 30 without making any inquiry into each component.
[0080] This high-level application is used by multiple system
administrators (or users) and the management of multiple disk
subsystems can be performed by the centralized management of an
exclusive control command and a configuration information
database.
[0081] According to the above embodiment, in the configuration of
the multiple disk subsystems shared from multiple hosts, there is
an effect in which multiple system administrators can collectively
define the system configuration that extends over the multiple disk
subsystems.
[0082] Further, the historical management of the system
configuration can be performed using the configuration information
database in which the configuration information of the whole system
was accumulated in point of time series.
[0083] Furthermore, there is an effect in which an influence that
the modification of the system configuration has on an application
can be estimated correctly. The cause of the performance
degradation of the application can be investigated.
[0084] Furthermore, there is an effect in which the modification
time of the system configuration and the additional time of the
logical unit capacity can be planned, estimated and posted.
[0085] According to the invention, in the configuration of multiple
(M units of) disk subsystems shared by multiple (N units of) hosts,
multiple system administrators (L persons) can manage the M units
of disk subsystems transversely and collectively and realize
predetermined setting quickly and simply.
[0086] The administrators can grasp an influence that a change of
the system configuration gives, in an application executed by a
host. The addition time according to plan with logical unit
capacity in the system can be determined.
[0087] Because the configuration information of the whole storage
system can be managed in a centralized manner in point of time
series, the degradation of the application performance caused by
the modification of the system configuration, the addition with
logical unit capacity into the storage system according to plan,
and the analysis and prediction of the other events can be
performed easily.
[0088] Having described a preferred embodiment of the invention
with reference to the accompanying drawings, it is to be understood
that the invention is not limited to the embodiments and that
various changes and modifications could be effected therein by one
skilled in the art without departing from the spirit or scope of
the invention as defined in the appended claims.
* * * * *