JPH08221211A - External storage controller - Google Patents

Abstract

PURPOSE: To give another instruction from a host device to an external storage controller also when a cache control part is in its busy state. CONSTITUTION: In the external storage controller 2a independently having the transfer route to a host device 1 and the transfer route to an external storage device 3a, performing the transfer of the host device 1 and the external storage device 3a via memories 23 and 24 and having a cache control part 25a performing the cache control of the memory 23, the present operation is held and the coupling state of the host device 1 and the cache control part 25a is disconnected when the cache control part 25a is in its busy state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external storage control device such as a disk control device for performing a channel transfer which is a higher-level device and an asynchronous transfer in which a transfer route to an external storage device operates independently in time. Regarding

[0002]

2. Description of the Related Art In a conventional magnetic disk controller, since channel transfer and disk transfer paths perform asynchronous transfer that operates independently in terms of time, all data transfer is performed via a memory in the controller. In other words, when writing data, the data of the track to be written is first expanded from the device, which is the magnetic disk device, in the memory, the part you want to write is written, and when reading the data, the data of the track you want to read is written to the device. It expands to memory from and reads only the part you want to read.

As a cache management method, the data once expanded in the memory is stored as it is for a certain period, and when a read or write access is made to the same data again, the data in the memory is directly used for reading or writing. Light up.

The cache managing module (CFE) always has information as to whether or not the data is expanded in the memory. When a read or write I / O (command) comes from the host device, the channel adapter (CA)
Inquires of the cache management module CFE if the track to be accessed is expanded in the memory. The cache management module CFE searches its own cache information for the track, and reports it to the channel adapter CA.
Upon receiving the report, the channel adapter CA reads or writes the data in the memory if there is data in the memory,
When there is no data in the memory, the device waits for the data to be expanded in the memory and then reads or writes.

For this reason, in the conventional device, the cache management module CFE has always been designed by limiting the processes to be performed at one time in order to guarantee a short-time response to the channel adapter CA.

Further, in the case of the write operation, there is a certain time lag before the data written in the memory is written in the actual device, and therefore the data must be guaranteed during that time.
Therefore, in order to obtain the same level of reliability as writing the data in the actual device by writing the data in the memory, the following is done.

FIG. 3 is an explanatory view of a conventional example, showing a normal write operation. In FIG. 3, a higher-level device 1, a disk control device 2, and a disk device 3, which is a device, are provided, and the disk control device 2 has a large-capacity memory 23 without a battery backup (SS: Shared Std).
non-volatile memory 24 (NVS: Nonvolat) that has a small capacity but is backed up by a battery.
ile Storage) is provided. It is to be noted that FIG.

First, before writing the data, the devices 1 to 3
Data of two tracks or two tracks is developed in the memory 23 in the control device. Then, in the actual write operation, the data on the memory 23 (SS) is rewritten, and further, the data is also written on the memory 24 (NVS). After that, writing of data to the disk device 3 is performed by the memory 24.
Be done from.

However, if the write operation is not continuously written back from the memory 24 to the disk device 3 due to continuous write operations, etc., data accumulates in the memory 24 (NVS) and eventually the memory 24 becomes full. Become.

This is the "Insufficient N"
In the state of “VS”, in the subsequent write operation, the memory 2
A write-through “Write Through” operation of writing data on the memory 23 without using the memory 4 is performed.

[0011]

The above-mentioned conventional ones have the following problems. In the high-performance disk control device, the cache management module CFE is busy for a long time (BUS) for active maintenance work and for rebuilding the cache management module CFE internal table.
The process of Y) cannot be avoided. Therefore, a response from the cache management module CFE to the channel adapter CA may be kept waiting for a long time.

When the memory 24 is full and the write-through operation is performed, two write operations for immediately writing data to the memory 23 and the disk device 3 are required to improve reliability, which complicates control. Therefore, there is a problem that the system throughput deteriorates.

The present invention solves the above-mentioned conventional problem, and when the cache management module CFE is in a busy state, the channel adapter CA immediately suspends the current operation and another I / O is sent from the host device to the channel adapter CA. It is also intended to improve the system throughput in the same manner as a normal process without requiring a complicated process such as a write-through operation.

[0014]

FIG. 1 is a diagram for explaining the principle of the present invention. In FIG. 1, 1 is a host device, 2a is an external storage controller, 3a is an external storage device, 21 is a channel adapter,
22 is a device adapter, 23 is a memory, 24 is a non-volatile memory, 25a is a cache management unit, and 26a is a resource management unit.

The present invention has the following configuration to solve the above problems. The transfer path with the host device 1 and the transfer path with the external storage device 3a are independently provided, and the transfer between the host device 1 and the external storage device 3a is performed via the memories 23 and 24, and the transfer of the memory 23 is performed. External storage control device 2a having a cache management unit 25a for performing cache management
When the cache management unit 25a is in the busy state, the current operation is suspended and the connection state between the host device 1 and the cache management unit 25a is disconnected.

Further, the transfer path to the host device 1 and the transfer path to the external storage device 3a are independently provided, and the host device 1
In the external storage control device 2a that transfers data to the external storage device 3a via the memories 23 and 24, the nonvolatile memory is used when writing data to the memory 23 and the nonvolatile memory 24 by a write operation. When there is no storage area in 24, the write operation is temporarily stopped and the data in the nonvolatile memory 24 is written in the external storage device 3a.

[0017]

The operation of the present invention based on the above configuration will be described. When the cache management unit 25a of the external storage control device 2a is in a busy state, the current operation is temporarily stopped instead of waiting for a response from the cache management unit 25a.
It should be separated from the host device 1. Thereby, another command can be issued from the host device 1 to the external storage control device 2a.

When writing data to the memory 23 and the non-volatile memory 24 of the external storage device 3a in the write operation, if the write operation continues and there is no storage area in the non-volatile memory 24, the write operation is performed. Once stopped, the data in the non-volatile memory 24 is stored in the external storage device 3a.
Try to write in. Then, the write operation is started at the time when the storage area of the nonvolatile memory 24 becomes free. In this way, the processing performance of the entire system can be improved because only simple control is performed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. §1: Description of Asynchronous Transfer Type Disk Controller FIG. 2 is an explanatory diagram of an embodiment of the present invention and shows the entire disk controller. The same components as those in FIGS. 1 and 3 are designated by the same reference numerals. As shown in FIG. 2, an asynchronous transfer type disk control device 2 is connected to a host device 1 and a disk device 3 which is an external storage device.

In the disk controller 2, a channel adapter (CA) 21, a device adapter (DA) 22, a memory (SS) 23, a non-volatile memory (NVS) 24, a cache management module (CF) connected by an internal bus.
E) 25 and a resource management module (RM) 26 are provided.

The channel adapter 21 has a channel path connected to a plurality of channels of the host device 1, receives data from the channels, writes it in the memories 23 and 24, and writes data written in the memory 23 to the host. It is transferred to the device 1.

The device adapter 22 writes data in the memories 23 and 24 to the disk device 3 which is an external storage device, and writes data read from the disk device 3 into the memory 23.

The memory 23 is a volatile memory having a large capacity but no battery backup.
The memory 24 is a non-volatile memory, and has a small capacity but is backed up by a battery.

The cache management module 25 manages information as to whether or not data has been expanded in the memory 23. The resource management module 26 manages the resources of the entire disk control device 2.

In the disk controller 2, when a read or write command (I / O) is received from the higher-level device 1, the channel adapter 21 determines whether the track for accessing the cache management module 25 is loaded in the memory 23. Contact us.

The cache management module 25 searches the cache information owned by the cache management module 25 to see if the track exists, and reports it to the channel adapter 21.
Upon receiving the report, the channel adapter 21 reads or writes the data in the memory 23 if there is data in the memory 23, and if there is no data in the memory 23, the data is expanded from the disk device 3 to the memory 23. Wait for
Read or write.

§2: Cache management module (CF
E) Description when Busy The disk control device 2 when the cache management module 25 is busy (in use) due to active maintenance work or another process such as rebuilding of internal tables
Will be described.

The channel adapter 21 is a host device 1.
Read or write instruction (I / O) from the channel
Accept. : The channel adapter 21 inquires of the cache management module 25 whether the track of the accepted instruction exists in the memory 23.

The response from the cache management module 25 was busy. : The channel adapter 21 keeps the current instruction as it is (for example, in the resource management module) and disconnects it from the channel that has issued the instruction.

For this reason, the channel adapter 21
The channel paths for and are empty and ready to accept commands from multiple channels. When the cache management module 25 is no longer busy, the cache management module 25 informs the resource management module 26 that it is no longer busy.

The resource management module 26 restarts the previously suspended instruction because the cache management module 25 is empty. In this way, the processing is delayed by waiting for the response of the cache management module 25, and it is possible to immediately receive another command without being combined with one channel for a long time.

§3: Description of the case where the capacity of the non-volatile memory (NVS) is full due to the previous write In the case of the write operation of the disk controller 2, first, before writing the data, the disk device 3 Data of one track or two tracks is expanded in the memory 23. And
In the actual write operation, the data in the memory 23 is rewritten, and further, the data is also written in the memory 24, and thereafter, the data writing to the disk device 3 is performed from the memory 24.

However, as in the case where the write operation continues, if the memory 24 is not written back to the disk device 3 indefinitely, the memory 24 becomes full.
Confidential NVS ”. The operation of the disk controller 2 in this state will be described below.

: The channel adapter 21 receives a write command from the channel. : The channel adapter 21 asks whether the track to be written in the cache management module 25 is loaded in the memory 23.

The cache management module 25 judges that the memory 24 is full and reports "Insufficient NVS" to the channel adapter 21. : The channel adapter 21, which receives the report that the memory 24 is full, temporarily stops the write operation and temporarily disconnects from the channel.

The resource management module 26 puts the disk controller 2 in a busy state. : The device adapter 22 writes the data in the memory 24 back to the disk device 3.

The cache management module 25 releases the memory 24 because the memory 24 is empty. : The resource management module 26 releases the busy state of the disk controller 2 because the memory 24 is released.

The channel adapter 21 connects to the channel again and starts the write operation. That is, once the disk control device is closed, the data in the memory 24 is promptly written back and the normal operation can be resumed. Rather than performing complicated operations such as conventional write-through and reducing the throughput of the entire system,
By using this method, the throughput of the entire system can be improved.

[0039]

As described above, the present invention has the following effects. : When the cache management module 25 is in a busy state, the current operation is temporarily suspended instead of waiting for the response from the cache management module 25 forever,
In order to separate from the host device 1, another command can be issued from the host device 1 to the disk controller 2.
Therefore, the disk control device 2 can accept another process that does not use the cache management module 25.

Non-volatile memory 2 in which write operation continues
4 has no storage area, the write operation is temporarily stopped so that the data in the non-volatile memory 24 is promptly written back to the disk device 3, and the non-volatile memory 24
Since the write operation is restarted when the storage area of the system is opened, the control of the entire system can be performed without performing complicated operation such as writing data to the memory 23 and the disk device 3 immediately and performing simple control. The processing performance can be improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of an example.

FIG. 3 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Higher-level device 2a External storage control device 3a External storage device 21 Channel adapter 22 Device adapter 23 Memory 24 Non-volatile memory 25a Cache management unit 26a Resource management unit

Claims (2)

[Claims] 1. A transfer path with a higher-level device and a transfer path with an external storage device are independently provided, and transfer between the higher-level device and the external storage device is performed via a memory, and cache management of the memory is performed. In the external storage control device having a cache management unit for performing, when the cache management unit is in a busy state, the current operation is suspended, and the connection state between the host device and the cache management unit is separated. Control device. 2. An external storage control device that has a transfer path to a higher-level device and a transfer path to an external storage device independently, and transfers the higher-level device and the external storage device via a memory, by a write operation. When writing data to the memory and the non-volatile memory, if there is no storage area in the non-volatile memory, the write operation is temporarily stopped and the data in the non-volatile memory is written to the external storage device. An external storage controller characterized by.