JPH061456B2 - Magnetic recording device - Google Patents

Description

DETAILED DESCRIPTION [Outline] A magnetic recording device in which a plurality of channel control units can access any one of a plurality of magnetic recording drive devices via any one of a plurality of magnetic recording control devices ( In the magnetic recording system), in the event of contention of access requests, the magnetic recording control device should effectively perform its busy processing, so that the busy judgment should be performed in at least two times, that is, a short time and a long time. It was done.

[Industrial application field]

The present invention relates to a magnetic recording device having a relatively long access response time such as a magnetic tape and a magnetic disk. This magnetic recording device has a magnetic tape drive device and a magnetic tape control device.

[Conventional technology]

In a bulk memory device adopting a conventional multi-cross call system, for example, a magnetic tape device, each magnetic tape controller checks the empty state of the magnetic tape driving device to drive the magnetic tape and confirms the access request from the host computer. Based on this, the magnetic tape drive is controlled. In this case, simultaneous access requests from the respective channel control units of a plurality of host computers or simultaneous access requests from a plurality of channel control units within the same host computer may be issued to the same magnetic tape drive device. . That is, access request contention occurs. In this case, in general, the channel control unit that has requested the access first and then requested the access receives a report from the magnetic tape control device that the magnetic tape drive device is busy.

[Problems to be solved by the invention]

The above-mentioned busy judgment in the magnetic tape control device uses the maximum time for selecting the magnetic tape drive device as a threshold value, and based on this threshold value, when the access command from the host computer is accepted in a rational manner. Is going. Therefore, when the busy response signals are all within the above threshold value and the access commands compete with each other, the busy response to the channel control unit requested later is delayed, and the system responsiveness deteriorates.

The above problem is commonly called bulk memory system,
Even in a magnetic disk device, etc., which has a long access time,
The same applies when the multi-cross call method is adopted.

More specifically, when the conventional magnetic tape control device reports the device busy to the channel control unit, the maximum time for selecting the magnetic tape drive device (for example, 200
μs) is set as a threshold value, and when the value has passed, if the magnetic tape drive is in a busy state, a busy report is made.

However, in this method, the channel control unit must wait until the above-mentioned maximum time elapses to obtain the device busy response from the magnetic tape control device, even if the magnetic tape drive device is not busy at an early stage. Even
The next process cannot be started until the maximum time has passed.

In particular, when the access from the channel control unit to the magnetic tape control device competes with the magnetic tape control device, even if the magnetic tape control device can immediately respond to the command accessed later, the above-mentioned maximum A busy response is made after a lapse of time. Therefore, the busy response to the channel control unit is delayed and the system cannot be efficiently driven.

The present invention solves this problem and enables the channel controller to quickly obtain a busy response and immediately move to the next processing, thereby shortening the busy response waiting time of the channel controller. , To speed up access processing to a magnetic tape control device.

[Means for solving problems]

In the present invention, a plurality of channel control units are provided on the host computer side, a plurality of magnetic recording control devices that can be connected to each of the plurality of channel control units are provided, and each of the plurality of magnetic recording control devices is provided. A plurality of magnetic recording drive devices that can be connected to the magnetic recording drive devices are provided so that any of the magnetic recording drive devices can be accessed in response to a command from the channel control unit via any of the magnetic recording control devices. In the above magnetic recording device, when one magnetic recording drive device controlled by the magnetic recording control device is in operation and an access command is issued from the other channel control unit, the magnetic recording drive device is controlled in a short time. A first busy signal that determines whether or not it can be used is sent to the other channel control section, and after a short time has elapsed, the magnetic recording drive device is driven for a long time. There characterized in that a least one of the second busy signal to determine whether available was to deliver to the other of the channel control unit, a magnetic recording device, is provided.

〔Example〕

An embodiment in which the present invention is applied to a magnetic tape device will be described with reference to FIGS. 1 (a) and 1 (b).

In FIG. 1A, a plurality of channel controllers 11 to 14 are provided on the host computer side 1, and a plurality of magnetic tape controllers 21 on the magnetic tape controller side 2 are provided so that these channel controllers can cross-call each other. Connected to ~ 24. Further, each magnetic tape controller is connected to a plurality of magnetic tape driving devices 31 to 34 on the magnetic tape driving device side 3, and any magnetic tape controller can be connected to the magnetic tape driving device 31.
Any one of ~ 34 can be selectively driven.
However, the connection relationship between the magnetic tape controllers 22 to 24 and the magnetic tape drive devices 31 to 34 is omitted in order to prevent the complexity of the drawing. The magnetic tapes are driven and driven by the respective magnetic tape drive devices 31 to 34, and data writing or data reading is performed based on the access command.

The channel controllers 11 to 14 are provided in different computers, or any two of them, for example, the channel controllers 11 and 12 are provided in the first computer, and the channel controllers 13 and 14 are provided in the second computer. Any of these may be used, but the respective channel controllers 11 to 14 can operate independently of each other.

According to the above multi-cross call system configuration, for example, the channel controller 11 can access any one of the magnetic tape driving devices 31 to 34 via the magnetic tape controller 21 or 22, for example, the magnetic tape driving device 31. Is possible. Similarly, since the channel controller 12 can access the magnetic tape drive device 31, if these timings overlap, so-called competition occurs.

FIG. 1B shows a busy determination circuit of the magnetic tape drive device in the magnetic tape controller 21. Similar circuits are provided in the other magnetic tape controllers 22 to 24.

In FIG. 1 (b), the busy determination circuit is a counter 21
1, timer 212, inverter 213,214, AND gate 215,21
6,217 and 218 are connected and configured as shown. The first busy report signal S-BSY-R1 from the AND gate 217 is applied to the count terminal CNT of the counter 211. Further, preset data D _PR , D _PR = 10 in this embodiment, is applied to the data terminal D, and the signal from the carrier output terminal CR is applied to the preset terminal PR. timer
212, the busy signal S-BSY is applied to the clear terminal CLR via the inverter 213 and reset, and then the clock signal CLK in the magnetic tape controller 21 is reset to the clock terminal CK.
By counting the clock signal CLK applied to
The signal S ₂₀ is output after the elapse of the first time t ₁ , t ₁ = 20 μs in this embodiment, and the signal S ₂₀ is output after the elapse of the second time t ₂ , t ₂ = 200 μs in the present embodiment. ₂₀₀
Are output from the _first and _second terminals T ₁ and T _2, respectively.

The operation of the circuit of FIG. 1 (b) will be described. When an access command is output from the channel controller 11 to the magnetic tape drive device 31 via the magnetic tape controller 21 and the magnetic tape drive device 31 is operating according to the access command, the magnetic tape drive device 31 is in a busy state. Becomes When an access command is output from the channel controller 12 to the same magnetic tape controller 21 and magnetic tape drive device 31 in this busy state, the “high” level busy signal S-BSY of the magnetic tape drive device 31 is applied to the AND gates 217 and 218. At the same time, the "low" level busy signal is applied to the low enable clear terminal CLR of the timer 212 via the inverter 213, and the timer 212 is cleared. The timer 212 counts the clock signal CLK, and after the lapse of t ₁ time,
The pulse signal S ₂₀ is output. In this case, counter 211
Are preset and their carry signal S _CR is at "high" level. Therefore, a high level signal is applied to both AND gates 215, and a high level signal is applied.
Applied to one input of AND gate 217. On the other hand, since the "high" level busy signal S-BSY is applied to the other input terminal of the AND gate 217, from the AND gate 217,
The first busy reporting pulse signal S-BSY-R1 corresponding to the pulse width of the pulse signal S ₂₀ is output.

The magnetic tape controller 21 does not report the busy status to the channel controller 12 which is requested later, based on the busy reporting pulse signal S-BSY-R1.

On the other hand, the busy report pulse signal S-BSY-R1 is applied to the count input terminal CNT of the counter 211 and subtracts 1 from the initially set count value D _PR = 10. Magnetic tape drive 31
As long as is in the busy state, the above operation is continuously performed.

When t ₂ = 200 μs has elapsed from the first time, the pulse signal S
₂₀₀ is output and the carry signal S of the counter 211 is output.
_CR becomes "low" level. Therefore, the "high" level signal is applied to both the AND gates 216, and the second busy reporting pulse S-BSY-R2 is output via the AND gate 218.

The magnetic tape controller 21 uses this busy reporting pulse S-
Based on BSY-R2, report busy status to channel controller 12. That is, after t ₂ = 200 μs has passed, a busy report similar to the conventional one is made.

If the magnetic tape drive device 31 is not in the busy state during the above period, the busy signal S-BSY becomes the “low” level. Therefore, the magnetic tape controller 21 receives the magnetic tape based on the access request from the channel controller 12. The drive device 31 is controlled.

In the above embodiment, the case where the busy report signal is generated in two stages, that is, the first busy report signal S-BSY-R1 and the second busy report signal S-BSY-R2 is generated, is described. It is possible to have multiple stages with a relationship.

For the above examples, the magnetic tape control
Although the magnetic tape drive device 31 in 21 has been described, the other magnetic tape drive devices 32 to 34 are independently processed in the same manner. The same applies to the other channel controllers 13 and 14.

In the above embodiments, the magnetic tape device is exemplified, but it goes without saying that the same can be applied to a magnetic disk device and the like.

〔The invention's effect〕

According to the present invention, the timing at which the magnetic tape control device makes a busy response to the channel control unit is a busy response in which the response is made in a short time (for example, 20 μs), and after the lapse of the short time, the conventional maximum time is set. It is divided into two stages of a busy response which responds after a lapse of time, and one magnetic tape driving device among a plurality of magnetic tape driving devices connected to the magnetic tape control device is operating while receiving the previous access command, that is, When in the busy state, even if an access command is further issued from the channel control unit, that is, even if there is a conflict of access commands, the magnetic tape control device first responds to this access command, that is, a subsequent access command. For example, it gives a busy response to the channel controller in 20 μs,
After that, for example, if the magnetic tape driving device is in operation after 200 μs has elapsed, a busy response is made. That is, the channel control unit can immediately obtain the busy response, and can immediately shift to the next processing. From the above, the busy response waiting time of the channel control unit is shortened,
It is possible to speed up the access processing to the magnetic tape control device.

[Brief description of drawings]

1 (a) and 1 (b) are diagrams showing the configuration and circuit of a magnetic tape device as an embodiment of the present invention. (Description of symbols) 1 ... Host computer side, 2 ... Magnetic tape controller side, 3 ... Magnetic tape drive section side, 11-14 ... Channel controller, 21-24 ... Magnetic tape controller, 31-34 ... Magnetic tape drive device, 211 ... Counter, 212 ... Timer, 213, 214 ... Inverter, 215-218 ... AND gate.

Claims (2)

[Claims] 1. A plurality of channel control units are provided on the host computer side, and a plurality of magnetic recording control units that can be connected to each of the plurality of channel control units are provided, and each of the plurality of magnetic recording control units. A plurality of magnetic recording drive devices that can be connected to the magnetic recording drive devices are provided so that any of the magnetic recording drive devices can be accessed in response to a command from the channel control unit via any of the magnetic recording control devices. In the above magnetic recording device, when one magnetic recording driving device controlled by the magnetic recording controlling device is in operation and there is an access command from the other channel control section, the magnetic recording driving device is controlled in a short time. The first busy signal that determines whether or not it can be used is sent to the other channel control unit, and the magnetic recording drive device uses it for a long time after the lapse of the short time. A magnetic recording apparatus, characterized in that at least one second busy signal for determining whether or not it is possible is sent to the other channel control section. 2. The magnetic recording device according to claim 1, wherein the magnetic recording drive device is a magnetic tape drive device, and the magnetic recording control device is a magnetic tape control device.