JP3266231B2 - Online capacity expansion method of external storage device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information processing system having an external storage device in each of a working system and a standby system. The present invention relates to a method for expanding the capacity of an external storage device performed online.

[0002]

2. Description of the Related Art Conventionally, the replacement of a device having the same capacity has already realized its function online. For example, when a device failure occurs, as a method for restoring information after device replacement, it is possible to restore information by copying all information stored in the active device to a newly replaced device. It is possible [Reference: Original CTRON large system 3 I / O control interface Edition Device multiplexing function (member device copy)].

[0003]

The conventional method described above is intended only for replacing a device with the same capacity, and cannot cope with a change in capacity.

[0004] On the other hand, external storage devices in a real-time information processing system have been diversified in information.
It is necessary to increase the capacity of the device and take over information. In order to increase the capacity, the capacity of the logical device generated for the external storage device is expanded, and the capacity of the logical device generated before expansion is unchanged, and a new logical device is generated (the number of logical devices). There are cases). For this reason,
It is necessary to provide a method for restoring information between devices having different capacities and a means for generating a plurality of logical devices online (capacity expansion processing and information restoration processing are performed without interrupting I / O requests generated therebetween). .

[0005] The present invention has been made in view of the above,
An object of the present invention is to provide an online storage capacity expansion method for an external storage device that appropriately and accurately expands the capacity or the number of logical devices with the expansion of the capacity of an external storage device.

[0006]

In order to achieve the above-mentioned object, an on-line capacity expansion method for an external storage device according to the present invention comprises a working system and a standby system, each of which has an external storage device. In an information processing system, when one or more logical devices generated corresponding to an external storage device and one virtual logical device are further defined in the logical device to perform device multiplexing and expand the capacity of the external storage device, The gist is that the area of the logical device generated corresponding to the storage device is expanded, information already stored is copied, and the virtual logical device holds an input / output request during the copy.

Further, the online storage capacity expansion method for an external storage device according to the present invention comprises an active system and a standby system.
When the capacity of an external storage device is expanded in an information processing system in which an external storage device is provided in each system and a plurality of logical devices are generated for one external storage device (hereinafter, referred to as multi-volume). In addition, by controlling device multiplexing realized by defining a logical device and a virtual logical device created for an external storage device, a new logical device is created for a new external storage device, thereby increasing the number of logical devices. The gist is to inherit information already stored.

[0008]

In the method for expanding the capacity of an external storage device according to the present invention, a logical device generated corresponding to the external storage device and one more virtual logical device are further defined for the logical device and the device is multiplexed. When the capacity of the external storage device is expanded, the area of the generated logical device is expanded, and information already stored in the expanded area is copied. During this copying, the virtual logical device holds the I / O request.

Further, the online storage capacity expansion method for an external storage device according to the present invention is realized by defining a logical device and a virtual logical device generated corresponding to the external storage device when expanding the capacity of the external storage device. Under the control of the device multiplexing, a new logical device is generated for the external storage device to add a logical device and take over the information already stored.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing embodiments of the present invention, an outline of the present invention will be described.

[0011] In an information processing system comprising an active system and a standby system and each system having an external storage device, when the capacity of the external storage device is expanded, that is, the external storage device is replaced with a large-capacity external storage device. As a method of allocating a logical device to a physically expanded area when the logical device is replaced with a new logical device, the method of expanding the size of a logical device that has already been generated and the capacity of a logical device that has already been generated remain unchanged. (A plurality of logical devices are generated). The main processing outline will be described for each case.

Case 1: In the case of expanding the size of the logical device, 1) The capacity of the logical device is determined by the information for managing the area (the information that exists in the external storage device and defines the area for storing data ( Hereinafter, it is referred to as format information)). Therefore, when extending a logical device, it is performed by changing the format information.

2) When restoring (copying) already stored information, only the area excluding the format information (hereinafter referred to as a data area) is copied to prevent overwriting of the format information.

3) In the copying of the data area, since the storage location is different due to the expansion of the capacity, normal read processing and write processing in file units are repeated. In this case, to control contention with I / O requests for the virtual logical unit,
The processing of the I / O request to the virtual logical device is temporarily suspended.

Case 2: In the case where a new logical device is generated, 1) Since the logical device generated before expansion is unchanged, restoration (copying) of already stored information is provided by the device multiplexing control. This is performed by copying all the information including the format information by the conventional copying function.

2) In the multi-volume, a plurality of logical devices are generated for an external storage device, and the correspondence of the logical device to the external storage device is defined by allocation information (hereinafter, referred to as volume information). Therefore, the volume information is changed in order to newly generate a logical device.

3) When the second and subsequent units are replaced, a copy process is performed for each logical device in order to copy the format information of the newly generated logical device. The copying process in this case is performed by full-area copying using a conventional copying function provided by the device multiplexing control.

The change of the size of a logical device and the generation of a new logical device as described above are performed by disconnecting the target device (state in which read / write processing for the apparatus cannot be performed: offline state). Here, even if the target device is disconnected, the state in which device multiplexing is defined continues, so that access to the virtual logical device is possible and the online state is maintained.

According to the present invention, service interruption of a general I / O request is concealed, the size of a logical device is increased and the number of logical devices is increased with the increase in the capacity of an external storage device, and information is transferred between different capacities. The main feature is to carry out.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a system configuration for implementing an on-line capacity expansion method for an external storage device according to a first embodiment of the present invention. The system shown in FIG. 1 includes an active system device 10a and a standby system device 10b. Each system has an external storage device 1, and one logical device 2 is assigned to each external storage device 1. . In addition, one virtual logical device 3 is defined in the system of FIG. 1 and thereby realizes a device multiplexing function. Then, if the application software, which is the higher-level software, issues an input / output request only to the virtual logical device 3, the processing for each logical device 2 is processed by controlling the device multiplexing. This input / output request (information) is transmitted to the active system device 10a and the standby system device 1
0b is synchronized and the same information is stored.

FIG. 2 is a diagram showing a system configuration for implementing an on-line capacity expansion method for an external storage device according to a second embodiment of the present invention. Similarly, the system shown in FIG. 1 also includes an active system device 20a and a standby system device 20b. Each system has an external storage device 1, and a plurality of logical devices 2 are assigned to each external storage device 1. I have. Further, in the system of FIG. 2, a virtual logical device 3 is defined for each of the logical devices 2, thereby realizing a device multiplexing function.
Then, the application software issues an I / O request only to the plurality of virtual logical devices 3 so that the processing for each logical device 2 is processed by controlling the device multiplexing. This input / output request (information) is transmitted to the active system device 20a.
Synchronization is established with the standby system device 20b, and the same information is stored.

The processing in the first embodiment shown in FIG. 1 will be described with reference to FIGS.

First, as shown in FIG. 3, a target device whose area is to be expanded is disconnected (a state in which read / write processing cannot be performed on the device: an offline state) to make the device replaceable. Here, even if the target device is disconnected, the state in which device multiplexing is defined continues, so that access to the virtual logical device is possible and the online state is maintained.

In the case of expanding the size of a logical device already allocated, after replacing the target device with a large-capacity device, management information for managing the logical device and the area (for storing data in the external storage device). (Information for allocating the area) is extended. FIG. 4 shows an outline of the processing. By changing the management information (* 1 in FIG. 4) for managing the area, the size of the management information area (* 2 in FIG. 4) and the size of the data storage area (* 3 in FIG. 4) are expanded (hereinafter, referred to as "3"). , Logical format). In order to take over the information stored in the active device, the information stored in the data storage area of the active device is copied to the external storage device in which the logical format has been implemented and the area has been expanded.

As shown in FIG. 4, the information to be copied includes all the information except the information for managing the area (* in FIG. 4).
4) Copy to the newly defined area. When the copying is completed, the information stored in the active and standby external storage devices becomes the same. In the copy processing when the size of the logical device is expanded, the storage location for inheriting information is different from that before the expansion. Therefore, processing is performed by repeatedly performing normal read processing / write processing for each file (* 5 in FIG. 4), and copying is not performed under control of device multiplexing. Therefore, it is necessary to control contention with general I / O requests for the virtual logical device during the copying process. As a method of controlling the contention, a general I / O request to the virtual logical device being copied is temporarily held in the device multiplexing control, and when the copying process is completed, the device is incorporated into an accessible state and then held. Perform the processing that has been performed. The general input / output request of the copy processing is delayed as a processing time because the processing is temporarily suspended, but the suspension is controlled by prioritizing the processing order at the time of resuming the processing.

Since it is not necessary to be aware of area expansion in the information takeover process performed when the second and subsequent units are replaced, all information must be copied using the conventional copying function provided by the device multiplexing control. Take over.

Next, the processing in the second embodiment shown in FIG. 2 will be described with reference to FIGS.

In the case of increasing the number of logical devices, a new logical device is generated. As shown in FIG. 5, a logical device (FIG. 5) is newly added to the physically expanded area (* 2 in FIG. 5).
* 3) is assigned.

In a multi-volume, a plurality of logical devices are generated for one physical device, and are defined by volume information. The change of the information is updated by creating a new logical device. Further, the format information is set for the newly created logical device. In the case of creating a new logical device, the existing logical device 2
Since there is no change in the information, there is no need to perform copying in consideration of the expansion of the area, and it is possible to inherit information by copying all information. The copying process in this case can be performed by the conventional copying function provided by the device multiplexing control. When the copying process is completed, the disconnected logical device is incorporated.

At the time of replacement of the second and subsequent units, as in the case of replacement of the first unit, a new logical device (* 1 in FIG. 6) is newly generated.
The copying process is performed for each logical device as shown in FIG. Here, the format information is also inherited by performing the conventional copying in which all information of each logical device is provided by the device multiplexing control.

[0032]

As described above, according to the present invention,
In an online environment, the service interruption of general I / O requests is concealed, and the expansion of the size of logical devices and the increase in the number of logical devices due to the increase in the capacity of external storage devices are not required. The generation is enabled, and the information already stored can be taken over between different devices.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration for implementing an on-line capacity expansion method for an external storage device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a system configuration for implementing an on-line capacity expansion method for an external storage device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing disconnection of an external storage device in the system of FIG. 1;

FIG. 4 shows a change of information for managing a logical device and an area in a case where the size of the logical device is expanded;
It is a figure showing the copy object at the time of exchange of the unit.

FIG. 5 is a diagram illustrating generation of a new logical device in a case where the number of logical devices is increased in the system of FIG. 2;

FIG. 6 is a diagram illustrating information restoration processing in a case where the number of logical devices is increased.

[Explanation of symbols]

 Reference Signs List 1 external storage device 2 logical device 3 virtual logical device 10a, 20a active device 10b, 20b standby device

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Claims (2)

(57) [Claims] 1. An information processing system comprising an active system and a standby system in which an external storage device is provided in each system, wherein one or a plurality of logical devices generated corresponding to the external storage device and the logical device and apparatus multiplexes further define one virtual logical unit, when expanding the capacity of the external storage device, to extend the area of the logical device that generated in the external storage device corresponding to the copy information already stored , The virtual
An online storage capacity expansion method for an external storage device, wherein a logical device holds an input / output request . 2. An information processing system comprising an active system and a standby system, each system having an external storage device and generating and using a plurality of logical devices for one external storage device. When the capacity of the storage device is expanded, a new logical device is generated for the external storage device by controlling device multiplexing realized by defining a logical device and a virtual logical device generated for the external storage device. A method for expanding the capacity of an external storage device online, wherein a logical device is additionally provided to take over information already stored.