JP3781377B2 - External storage controller and data transfer method between external storage controllers - Google Patents

Description

The present invention relates to an external storage subsystem that stores data by a write command from a host device, and more particularly to an external storage subsystem that transfers the same data to another external storage subsystem.

When data used in a host device is held in a plurality of external storage devices, primary and secondary external storage devices that hold the same data may be provided under different external storage control devices. In this case, when these external storage control devices are connected and a write command is received by the external storage control device that controls the primary external storage device, the primary external storage control device controls the secondary external storage device. By issuing this write command to the control device, the data in the primary and secondary external storage devices are matched.

In US Pat. No. 5,155,845, an external storage control device that controls a primary external storage device and an external storage control device that controls a secondary external storage device are connected, and a primary external device that has received a write command from a host device. It is described that the storage control device performs data transfer to the secondary external storage control device and performs write processing to the primary / secondary external storage device in parallel.

When the data in the external storage device is regarded by the host device as being in the CKD (count, key, data) format used in the large computer system, a channel command instructing the data transfer for each individual record is consecutive. Issued.

Here, consider a case where a plurality of records are continuously written in one command chain. In an external storage subsystem having primary and secondary external storage devices that hold the same data under different external storage control devices, R1, R2 and disk devices that are primary storage control devices from the channel device that is the host device When a command chain (DEFINE EXTENT / LOCATE RECORD / WRITE (R1) / WRITE (R2) / WRITE (R3)) for writing three consecutive records of R3 is issued, the channel device and the primary disk controller, and In the exchange of data with the secondary disk control device, a command chain is generated several times between the primary and secondary disk control devices for every data transfer of the write record as in the processing sequence of FIG.

Further, when data is duplicated with such a system configuration, the distance between the primary and secondary external storage control devices is increased from the viewpoint of switching to the backup system in the event of a disaster, and an optical fiber is used for the interface. For this reason, the command chaining time, which is considered to be almost fixed for metal cables, is in a state where the influence of the cable length of the interface cannot be ignored. Furthermore, since the above-described data duplication is a backup function, it is necessary to minimize the influence on the normal processing by the writing processing to the secondary external storage control device.

However, when multiple writes are executed in one command chain as described above, the number of command chains between the primary external storage control device and the secondary external storage control device increases, so that the secondary external storage control The command chaining time required for the writing process to the device cannot be ignored, and the backup process may greatly increase the throughput of the normal process.

The object of the present invention is to optimize the write processing time to the secondary external storage control device in consideration of the command chaining time between the primary and secondary external storage control devices, thereby achieving the original purpose even in the above-described situation. It is to provide means that can.

To achieve the above object, a storage system according to the present invention is connected to a plurality of first storage devices, a host device, and the plurality of first storage devices, receives write data from the host device, and Controls data writing to a plurality of first storage devices, and is connected to another storage control device connected to the plurality of second storage devices, and transfers the write data to the other storage control devices. A storage control device, wherein the storage control device acquires and stores information about functions provided in the other storage control device.

According to this, the command chaining time between the primary and secondary external storage control devices is predicted, and before the write processing to the secondary external storage control device is started, the predicted value and the higher order device are issued to the primary external storage control device. It is possible to predict the write processing time from the command to the secondary external storage controller. In addition, the estimated processing time and the data processing time when the data for the write record or the data for a plurality of tracks including the write record are transferred to the secondary external storage controller by a dedicated command at one time are compared. It is possible to instruct the external storage controller to select an appropriate command chain and write the data together. The above command chaining time is measured by measuring the command chaining time from the specific command issued between the primary and secondary external storage control devices to the next command, or the interface cable length between the primary and secondary external storage control devices from the outside in advance. This is realized by setting and calculating the command chaining time from this interface cable length.

On the other hand, the write processing time to the secondary external storage control device can be calculated from the above information and command information issued to the primary external storage control device. That is, a command chain used for data input / output includes specific and at least two channel commands before a command for starting data transfer. For example, in the case of an external storage control device, the DEFINE EXTENT command and the LOCATE RECORD command are issued before data transfer, and the number of processing records and the data length are given by the LOCATE RECORD command. It is possible to calculate the transfer amount.

Further, the command chaining time between the primary and secondary external storage control devices depends on the interface cable length and the processing capability of the external storage control device, but hardly depends on the commands before and after the command chaining. Therefore, the command chaining time during data transfer can be predicted by measuring two command chaining times. Note that when installing a backup system, the interface cable length between the primary and secondary external storage control devices and the support function of the external storage control device are already known, and this information is set in the primary external storage control device when the system is installed. The command chaining time can also be predicted from the set interface cable length.

If the command chaining time can be predicted, the processing time when the command chain from the channel is issued to the secondary external storage control device can be predicted from the data transfer amount. Alternatively, it is possible to issue an optimum command chain to the secondary external storage control device by comparing the processing time when the data for a plurality of tracks including the write record is collectively written and transferred at one time. it can.

In addition, the external storage control device according to the present invention transfers the data to the external storage control device that receives the write command from the data buffer in the external storage control device in response to the write command. Means for confirming the presence in the data buffer of the control device, and means for transferring the data. Furthermore, the transfer processing time can be further shortened by transferring the physical data in the data buffer including the control byte and the check byte together in the data transfer.

The storage control device according to the present invention is connected to the host device and the plurality of first storage devices, receives write data from the host device, controls writing of data to the plurality of first storage devices, and A storage control device that is connected to another storage control device connected to the plurality of second storage devices and transfers the write data to the other storage control device, and is provided in the other storage control device It is characterized by acquiring and storing information about functions.
According to this, the command chaining time between the primary and secondary external storage control devices is predicted, and before the write processing to the secondary external storage control device is started, the predicted value and the higher order device are issued to the primary external storage control device. It is possible to predict the write processing time from the command to the secondary external storage controller. In addition, the estimated processing time and the data processing time when the data for the write record or the data for a plurality of tracks including the write record are transferred to the secondary external storage controller by a dedicated command at one time are compared. It is possible to instruct the external storage controller to select an appropriate command chain and write the data together. The above command chaining time is measured by measuring the command chaining time from the specific command issued between the primary and secondary external storage control devices to the next command, or the interface cable length between the primary and secondary external storage control devices from the outside in advance. This is realized by setting and calculating the command chaining time from this interface cable length.

According to the present invention, for example, in a data transfer process between a primary disk controller and a secondary disk controller, a command chain received from a channel device is directly issued to a secondary disk controller, and a write record The command chain to be issued to the secondary disk controller so that the processing time is minimized. It is also possible to make a selection, and it is possible to minimize the write processing time to the secondary disk device which is a backup process.

Hereinafter, an embodiment of the present invention will be described. FIG. 1 is a configuration diagram of a data processing system according to an embodiment of the present invention. This data processing system includes a main storage device 1, a channel device 2, a main storage device 6 that is a backup system, and a channel device 7. Further, a primary disk control device 3 having a buffer memory 4, a primary disk device 5, and a secondary disk control device 8 and a secondary disk device 10 incorporating a buffer memory 9 are included. The channel device 2 and the primary disk control device 3 are connected by an interface cable 11, and the primary disk control device 3 and the secondary disk control device 8 are connected by an interface cable 12.

As shown in FIG. 2, in addition to the buffer memory 4, the primary disk control device 3 includes a channel command analysis unit 31, a secondary disk control device issue command determination unit 32, a secondary disk control device management information table 33, a timer 34, and a secondary disk. It comprises a control device command issuing unit 35 and a cable length / secondary disk control device function determining unit 36. Reference numerals 31 to 33 and 35 to 36 denote functional blocks realized by a microprogram executed by a microprocessor built in the disk control device 3. The timer 34 is a hardware counter that is counted up at a constant period. The secondary disk control device 8 has the same configuration.

In the primary disk control device 3, the timer 34, the secondary disk control device command issuing unit 35, and the cable length / secondary disk control device function determining unit 36
Measures the command chaining time between the primary and secondary disk controllers. Then, the command chaining time Tsg measured by the timer 34 at the time of command processing issued when the primary / secondary disk device pair is established is stored in the management table 33 in the primary disk control device.

Further, the primary disk control device acquires the support function level of the secondary disk control device when the primary / secondary disk device pair is established, and similarly stores it in the management table 33 in the primary disk control device. This information indicates whether or not it is possible to receive an instruction to write the data for the write record or the data for a plurality of tracks including the write record to the secondary disk controller when the write command is issued to the secondary disk controller later. Used for judgment.

If the secondary disk control device issue command determination unit 32 determines that the dedicated command cannot be received based on the support function level information, when the write command is received from the channel device 2, the secondary disk control device command issue unit 35 unconditionally. A command chain from the channel device is issued to the secondary disk control device. Therefore, it is possible to connect to a conventional model that does not support this function.

When a write command is issued from the channel device 2 to the primary disk control device 3,
The channel command analysis unit 31 determines whether the write command is for a disk device forming a primary / secondary pair.

If it is for the primary / secondary pair forming disk device, the information from the secondary disk control device management information table 33, the number of transfer records N of the LOCATE command analyzed by the channel command analysis unit 31, and the average record length L are used. Then, a comparison graph is created when the received command chain is directly issued from the channel device to the secondary disk control device and when one track including the write record is transferred together (see FIG. 6). Here, the straight line I can be expressed by the following equation from the command chaining time Tsg between the primary and secondary disk control devices, the analysis value, and the data transfer speed V between the primary and secondary disk control devices 3 and 8 that have become known.

Ts = NL / V + (N−1) Tsg
A straight line II represents the transfer time Ts ′ (a constant value) when the record length Na for one track of the record length L is transferred together.

Ts ′ = NaL / V + Tsg
The secondary disk controller issued command determination unit 32 issues the command chain received from the channel device to the secondary disk controller from the comparison graph and the number N of records transferred in the command chain as it is, or collects one track. Determine whether to transfer.

Assuming the case of writing 6 records to the 8 records / track track shown in FIGS. 4, 5 and 6, the graph shows the number of records including the contacts of the straight lines I and II (4 records) as one boundary. If the data is transferred together, it can be predicted that the processing time can be shortened by reducing the number of command chains.

The secondary disk controller command issuing unit 35 issues an optimized command chain to the secondary disk controller 8 in accordance with the instruction from the secondary disk controller issued command determination unit 32.

It is a block diagram of the data processing system in the Example of this invention. It is an internal block diagram of the disk control apparatus in the Example of this invention. FIG. 3 is a diagram illustrating data exchange between a channel device, a primary disk control device, and a secondary disk control device, which are host devices. FIG. 6 is a diagram showing a case where data transfer is performed between primary and secondary disk control devices in units of tracks in the embodiment of the present invention. It is a figure which shows the data of 8 records / 1 track stored in the data buffer in the disk control apparatus in the Example of this invention. It is a figure showing the relationship between the number of transfer records and processing time in the Example of this invention.

Explanation of symbols

3 Primary disk control device 8 Secondary disk control device 12 Interface cable between primary and secondary disk control devices 32 Secondary disk control device issue command determination unit 33 Secondary disk control device management information table 34 Timer 35 Secondary disk control information command issue unit 36 Cable length / secondary Disk controller function judgment unit

Claims (10)

A plurality of first storage devices;
It is connected to the host device and the plurality of first storage devices, wherein the host device receives the write data by controlling the write of data to the plurality of first storage devices, and a plurality second A storage control device connected to another storage control device connected to the storage device and transferring the write data to the other storage control device;
With
Storage system wherein the storage controller, characterized in that acquires and stores information about the functions provided in prior Symbol another storage controller. The storage system of claim 1, wherein
The storage control device associates the first storage device with the second storage device,
When associating the first storage device and the second storage device, information about functions provided by the other storage control device is acquired from the other storage control device and stored. Storage system. The storage system of claim 1, wherein
Storage system wherein the storage controller, characterized by a Turkey that having a management means for storing information about functions provided in the other storage controller. The storage system of claim 3 .
The management means includes a management information table in which information about functions provided in the other storage control device is stored, and functions provided in the other storage control device acquired from the other storage control device. storage system comprising a benzalkonium to store information in the management information table. The storage system of claim 3 .
The storage control device associates the first storage device with the second storage device,
When associating the first storage device and the second storage device, information about functions provided by the other storage control device is acquired from the other storage control device and stored. Storage system. The storage system of claim 1 , wherein
The storage system, wherein the storage control device varies information to be issued to the other storage control device according to a function provided by the other storage control device. The storage system of claim 1, wherein
The storage controller is
Controls reading of data from the host device to the plurality of first storage devices,
A read command from the host device is sent to the other storage control device when data to be read requested by the host device exists in the other storage control device. Storage system. The storage system of claim 1, wherein
In the storage control device, confirm that the write data from the host device exists in the other storage control device,
The storage system, wherein the storage control device sends a write command from the host device to the other storage control device . The storage system of claim 1, wherein
The other storage control device has a function different from the function of the storage control device. Connected to a host device and a plurality of first storage devices, receives write data from the host device and controls writing of data to the plurality of first storage devices, and to a plurality of second storage devices A storage control device connected to another connected storage control device and transferring the write data to the other storage control device,
Acquire and store information about functions provided in the other storage control device
A storage control device.

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