JPH07192373A - Library device - Google Patents

Abstract

PURPOSE:To obtain a library device which can shorten the mean movement distance of a conveyance means. CONSTITUTION:When cartridges 1 are changed, the cartridge 1 in storage 3 is stored in one free storage part 3a' of a 1st group G1 and then the cartridge 1 in a drive part 2 is stored in the other free storage part 3a' of the 1st group G1 an the cartridge 1 in the former free storage part 3a' is conveyed to the drive part 2. Consequently, when plural cartridges 1 wherein successive data are divided and stored are accessed, the time required to change the cartridges 1 is shortened. If a cartridge 1 to be accessed next is stored in a group other than the 1st group G1 at this time, cartridges 1 of the lowest frequencies of use in respective groups are moved sequentially to groups of longer conveyance distances, so the cartridges 1 of the high frequencies of use are always arranged in order from the 1st group G1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a library that stores a plurality of recording media such as optical disks, magnetic disks or magnetic tapes, and automatically exchanges the recording media to access data to the recording media. It relates to the device.

[0002]

2. Description of the Related Art An optical disc device has a storage capacity of several hundred MB for an optical disc medium having a diameter of 90 mm or about 1 GB for an optical disc medium having a diameter of 130 mm, and is a storage device capable of exchanging the optical disc medium. There is a characteristic that a storage device having an infinite storage capacity can be equivalently configured by replacement.

In recent years, taking advantage of such characteristics of the optical disk device, the optical disk medium is automatically replaced,
An optical disk library device has been developed that provides a storage capacity of 1 TB class. As shown in FIG. 6, this library device is configured to load a standard cartridge 1 containing one optical disk medium into a drive unit 2 to read / write data from / into the optical disk medium in the cartridge 1. The cartridge 1 in the drive unit 2 can be replaced by transporting an arbitrary cartridge 1 stored in the storage unit 3a of the warehouse 3 by the hand unit 4 of the automatic handling mechanism.

Usually, when replacing a cartridge, the cartridge 1 taken out from the drive unit 2 is conveyed by the hand unit 4 to a predetermined storage unit 3a of the warehouse 3, and then the hand unit 4 is stored in the storage unit of an arbitrary cartridge 1. 3a, and finally a new cartridge 1 is conveyed to the drive unit 2.

By the way, in the library device, it is assumed that the data recorded by being divided into a plurality of specified recording media are continuously reproduced. Therefore, an evacuation unit 5 for temporarily accommodating the cartridge 1 is provided near the drive unit 2, and the cartridge 1 to be accessed next is placed in a standby state in advance in the evacuation unit 5, whereby each data is divided. It is proposed that the replacement time of the cartridge 1 is shortened. In this case, when the cartridge 1 to be accessed next is moved from the predetermined storage section 3a of the warehouse 3 to the one retreat section 5 by the hand section 4 and the reading / writing of the data with respect to the previous cartridge 1 is completed, it becomes unnecessary. After once storing the cartridge 1 in the other retreat section 5, the cartridge 1 of the one retreat section 5 is loaded into the drive section 2 to resume reading and writing of data. After that, the cartridge 1 stored in the other retreat portion 5 is returned to the predetermined storage portion 3 a of the warehouse 3.

[0006]

However, in the optical disc library apparatus, in order to replace the cartridge 1 of the optical disc medium, first, the drive unit 2 is used.
It is necessary to return the cartridge 1 loaded therein to a predetermined position of the warehouse 3 and then convey the arbitrary cartridge 1 stored in the predetermined position of the warehouse 3 to the drive unit 2. Therefore, in the conventional optical disk library device,
If the replacement of the cartridge 1 is included, there is a problem that the average access time reaches as much as ten and several seconds. Further, in the conventional library apparatus, since the cartridge 1 near the drive unit, which has little influence on the access time, is also moved to the retraction unit 5 in advance, the average movement distance of the hand unit 4 increases more than necessary, There is a problem that the replacement capacity of the cartridge 1 is deteriorated when the operation of the hand unit 4 becomes frequent, such as when a plurality of drive units 2 are operating simultaneously for one warehouse 3. .

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a library device which can shorten the average moving distance of the conveying means.

[0008]

In order to achieve the above object, the present invention has a warehouse having a large number of storage units, a large number of recording media stored in the storage units of the warehouse, and writing and reading of data to and from the recording media. In a library device including a drive unit for performing the above, and a transport unit for exchanging a recording medium loaded in the drive unit with an arbitrary recording medium stored in a warehouse, each storage unit of the warehouse is provided with respect to the drive unit. It is divided into at least two or more groups having different transport distances, and at least two empty storage sections are provided in at least the group having the shortest transport distance, and when the recording medium is exchanged by the transport means, it is set in an arbitrary warehouse. After storing the recording medium in one empty storage unit, store the recording medium in the drive unit in the other empty storage unit and dry the recording medium in one empty storage unit. When the recording medium is stored in a group other than the group having the shortest transport distance, the group having the shortest transport distance to the group having the shortest transport distance with respect to the group having the recording medium stored therein In each of the groups, the recording medium having the lowest use frequency is sequentially moved to the group having the longer transport distance.

[0009]

According to the library device of the present invention, when the recording medium is exchanged by the conveying means, after the arbitrary recording medium of the warehouse is stored in one empty storage portion, the recording medium in the drive portion is empty of the other recording medium. Since the recording medium stored in the storage unit and the recording medium in one empty storage unit is conveyed to the drive unit, it is necessary to replace each recording medium when accessing a plurality of recording media in which continuous data is divided and stored. Time can be shortened. At that time, when the recording medium to be accessed next is stored in a group other than the group having the shortest transport distance, the group having the shortest transport distance from the group having the shortest transport distance is transferred to the group having the shortest transport distance. Since the recording media with the lowest usage frequency are sequentially moved to the group with the longer transport distance from each group up to the shortest group, the recording media with the highest usage frequency are always arranged in order from the group with the shortest transport distance. To be done.

[0010]

1 and 2 show a first embodiment of the present invention, and FIG. 1 is a schematic configuration diagram of a library apparatus. This library device is provided with a plurality of cartridges 1, a drive unit 2, a warehouse 3, and a hand unit 4 as in the conventional example, and the hand unit 4 constitutes a conveying means together with a moving mechanism and a control unit (not shown). .

The cartridge 1 accommodates an optical disk as a recording medium, and is loaded in the drive unit 2 so that the drive unit 2 can be accessed.

The drive unit 2 is an optical disk drive device arranged below the warehouse 3 and is adapted to write and read data to and from the recording medium in the cartridge 1.

The warehouse 3 has a plurality of storage units 3a arranged in the vertical direction, and each storage unit 3a stores an unspecified cartridge 1. Each storage portion 3a is divided into a total of two groups divided in the vertical direction,
The shorter average transport distance than the drive unit 2 is the first group G1, and the longer average transport distance is the second group G2. Further, two empty storage portions 3a 'are always secured in the first group G1.

The hand unit 4 is moved between the drive unit 2 and the warehouse 3 by its moving mechanism and control unit,
The carrying, loading and unloading of the cartridge 1 is performed, but the specific configuration thereof is described in the prior art publications and the like, and therefore its explanation is omitted. The operation of the hand unit 4 is controlled by a program described later stored in the control unit, and the control unit controls the frequency of use of each cartridge 1, that is, the cartridge 1
Is stored in the drive unit 2 within a predetermined time.

In the library device configured as described above, the operation of the hand unit 4 when a plurality of specified cartridges 1 are continuously accessed is shown in the schematic configuration diagram of FIG. 1 and the flowchart of FIG. It will be described with reference to FIG. The numbers attached to the solid arrows in FIG. 1 indicate the order of operation of the hand unit 4.

First, when there is an instruction to replace the cartridge 1 (S1) and the next cartridge 1 exists in the first group G1 of the warehouse 3 (S2), the stage where the reading and writing of the cartridge 1 in the drive unit 2 is completed. (S3), the cartridge 1 in the drive unit 2 is removed and (S3)
4) Move to the one empty storage portion 3a 'of the first group G1 and store the cartridge 1 in the one empty storage portion 3a' (S5). Then, after the cartridge 1 is moved to the storage portion 3a in which the next cartridge 1 is stored and the cartridge 1 is taken out, the cartridge 1 is moved to the drive portion 2 and the cartridge 1 is loaded into the drive portion 2 (S6), and then the process returns to step S1 to drive. It moves to the part 2 and waits until the next exchange order is given. Here, a new cartridge 1 is created by the drive unit 2.
Data is written to or read from.

As shown in FIG. 1, if the cartridge 1 to be accessed next does not exist in the first group G1 (S2), that is, if it exists in the second group G2, the next cartridge 1 Is moved to the storage portion 3a in which the cartridge 1 is stored, the cartridge 1 is taken out, and the cartridge 1 is moved to one empty storage portion 3a 'of the first group G1 to store the cartridge 1 in the one free storage portion 3a' (S7). .
Next, when the reading and writing of the cartridge 1 in the drive unit 2 is completed (S8), the cartridge 1 in the drive unit 2 is taken out (S9) and moved to the other empty storage unit 3a 'of the first group G1. , The cartridge 1 is stored in the other empty storage portion 3a '(S10). Subsequently, the cartridge 1 stored in the one empty storage portion 3a 'of the first group G1 is taken out, moved to the drive portion 2, and the cartridge 1 is loaded into the drive portion 2 (S11).
Thereafter, the cartridge 1 having the lowest use frequency is taken out from the first group G1 based on the data stored in the control unit (S12), and is taken out in the empty storage unit of the second group G2, that is, step S7. The cartridge 1 is stored in the storage portion 3a that has been stored (S13),
The process returns to step S1 to move to the drive unit 2 and wait until there is a next exchange command. In this process, two empty storage portions 3a 'are secured in the first group G1 again. As a result of such rearrangement processing, the cartridge 1 which is frequently used
Is the first group G that has a shorter transport distance than the drive unit 2.
Will be placed at 1. Further, the rearrangement process is performed by utilizing the idle time after the replacement of the cartridge.

Next, the average movement distance of the hand unit 4 in the library apparatus of this embodiment will be described in comparison with the conventional example. Here, for the sake of simplicity, the shortest access distance to the warehouse 3 is 0 and the maximum access distance is Lmax. Further, the operation of the hand unit 4 will be described by dividing it into three stages in total. That is,
The operation of moving the cartridge 1 to be accessed next to the vicinity of the drive unit 2 prior to the access is referred to as prior access, and the cartridge 1 in the drive unit 2 is taken out and moved to the vicinity of the drive unit 2 to drive the next cartridge 1. The operation of loading the unit 2 is called main access, and the operation of returning the cartridge 1 moved near the drive unit 2 to the warehouse 3 is called trailing access.

First, in the prior access of the conventional example,
The hand unit 4 moves toward the storage unit 3a that stores the cartridge 1 to be accessed next.
Since there is a predetermined storage unit 3a for storing the storage unit 3 from one end to the other end of the warehouse 3 with an average probability, the average movement distance of the hand unit 4 is Lmax / 2. Next, the hand unit 4 grips the next cartridge 1 and moves to the one retracting unit 5, but since it is assumed that the drive unit 2 and the retracting unit 5 are at the same position, the hand unit 4 in this case is The average moving distance is also Lmax / 2. Finally, the hand unit 4 returns to the drive unit 2, but the moving distance at this time is zero.

Next, in this access, the hand unit 4
Transports the cartridge 1 which is no longer needed after the reading and writing of data in the drive unit 2 to the other retreat unit 5, and then moves from the other retreat unit 5 to the one retreat unit 5 and the one retreat unit 5 The cartridge 1 stored in the drive unit 2
Transport to. Since the moving distance of the hand unit 4 in these operations is 0 according to the assumption, the average moving distance is also 0. However, the average moving distance = 0 in this case is established by the assumption, and actually the hand unit 4 moves only three times in total to load the cartridge 1 into the drive unit 2.

In the subsequent access, the hand unit 4 moves to the other retracting unit 5 and after the cartridge 1 stored in the other retracting unit 5 is stored in the predetermined storing unit 3a of the warehouse 3. , Finally, it returns to the position of the drive unit 2, but this has a relation to follow the opposite route to the preceding access,
The average movement distance of the hand unit 4 at this time is 0 + Lmax / 2 + L
max / 2 = Lmax.

Therefore, the average moving distance of the hand unit 4 is 0 in the main access, but is Lmax in each of the preceding access and the subsequent access. Therefore, the average moving distance obtained by combining these is given by the following equation (1). expressed.

Average moving distance (preceding access + main access + subsequent access) = 0 + Lmax + Lmax = 2Lmax (1) On the other hand, in the present embodiment, the entire first group G1 closer to the drive unit 2 is the save unit of the conventional example. Corresponding, the first group G
Cartridge 1 belonging to 1 is not a target of prior access.

That is, the preceding access of this embodiment is performed only to the second group G2, and in this case, the cartridge 1 to be accessed next is stored in the empty storage section 3a 'which is always secured in the first group G1. It is temporarily stored in one side. At this time, the hand unit 4 moves from the drive unit 2 to the second group G2 by the average moving distance 3Lmax / 4 and reaches the storage unit 3a in which the next cartridge 1 is stored, grips the cartridge 1 and It moves to the empty storage section 3a '. Here, the empty storage portion 3a 'is the first group G1.
Therefore, the average movement distance of the hand unit 4 is Lmax / 2. Next, the hand unit 4 moves for the average access by the average moving distance Lmax / 4 and returns to the drive unit 2. That is, the cartridge 1 to be accessed next by this preceding access is arranged in the first group G1. If the cartridge 1 to be accessed next time originally belongs to the first group G1, the preceding access is not performed.

Next, in this access, the hand unit 4
Drives the cartridge 1 which has become unnecessary after the data reading / writing is completed by the average moving distance Lmax / 4 and temporarily stores it in the other empty storage portion 3a 'of the first group G1. Then, the hand unit 4 makes the first access by the first access.
The cartridge 1 is moved to the position of the cartridge 1 stored in one empty storage portion 3a 'of the group G1 or the cartridge 1 originally belonging to the first group G1. At this time, since the hand unit 4 moves between any two points in the first group G1, the average moving distance at that time is Lmax / 6 (for example, “real time”; J. Martin, stable translation by Kitahara, P546
Etc.). Then, the hand unit 4 grips the cartridge 1 to be accessed next and moves by the average moving distance Lmax / 4, moves to the drive unit 2 and loads the cartridge 1. Cartridge 1 to be accessed next in this access
If the cartridge 1 originally belongs to the first group G1, a new empty storage section 3a 'is generated in the first group G1 when the cartridge 1 is conveyed to the drive section 2, so that
The positions of the two empty storage portions 3a 'of the group G1 change sequentially. However, the next cartridge 1 is used as the second group G2.
When the cartridge 1 is taken out from the empty storage unit 3a 'of the first group G1 by prior access, the cartridge 1 is transferred to the drive unit 2 from the empty storage unit 3a'. The position of the empty storage portion 3a 'does not change. Incidentally, here, the hand unit 4 is the drive unit 2,
Since the one empty storage part 3a 'and the other empty storage part 3a' are sequentially moved, the total movement distance of the hand part 4 does not change regardless of the position of each empty storage part 3a '.

In the subsequent access, the cartridge 1 having the lowest use frequency is selected from the first group G1 and is stored in the storage portion 3a in which the cartridge 1 taken out from the second group G2 in the previous access is stored. It is stored. Therefore, when the cartridge 1 to be accessed next time originally belongs to the first group G1, the subsequent access is not performed. In the subsequent access, the hand unit 4 moves from the drive unit 2 by the average moving distance Lmax / 4 to reach the position of the cartridge 1 which is least frequently used in the first group G1, and the cartridge 1 moves the average moving distance. Lmax /
It is moved by 2 and stored in the second group G2, and finally moved by the average moving distance of 3Lmax / 4 and returned to the drive unit 2.
When this process is completed, two empty storage portions 3a 'are secured in the first group G1 again. As a result of the subsequent access, the cartridge 1 which is frequently used is rearranged in the first group G1 which has a short transport distance.

Here, the probability that the cartridge 1 to be accessed next exists in the first group G1 is α1 (1 ≧ α1).
≧ 0.5), the probability of being present in the second group G2 is 1−α
If it is set to 1, the average movement distance of the hand unit 4 in this access is expressed by the following equation (2), and the average movement distance of the hand unit 4 including the preceding access and the trailing access is expressed by the following equation (3).

Average moving distance in this access (number of groups = 2) = Lmax / 4 + Lmax / 6 + Lmax / 4 = 2Lmax / 3 (2) Average moving distance in preceding access and subsequent access = 2 (1-α1) (3Lmax / 4 + Lmax / 2 + Lmax / 4) = 3 (1-α1) Lmax (3) At this time, a plurality of cartridges 1 having continuous data
Are concentrated in the first group G1 (α1
= 1), all cartridges 1 to be accessed next are the first
Since it exists in the group G1, the average movement distance of the hand unit 4 in the main access is 2Lmax / 3 from the formula (2), and the average movement distance of the hand unit 4 in the preceding access and the subsequent access is 0 from the formula (3). Becomes Also, compared with the conventional case shown in equation (1), the average movement distance in this access increases from 0 to 2Lmax / 3, but when combined with the preceding access and the subsequent access, 2Lmax /
On the other hand, in this embodiment, it is 2Lmax / 3, which is about 66% reduction. Further, unlike the main access, the preceding access and the subsequent access are not performed in the probability event, that is, when the cartridge 1 to be accessed next originally belongs to the first group G1. This means that part 4 does not move at all. That is, in the conventional preceding access and trailing access, the hand unit 4 moved a total of 6 times to move the average moving distance 2Lmax, but in the present embodiment, it does not move at all.

Further, the data is the first group G1 and the second group.
Assuming that the average is distributed to the group G2 (α1 = 0.5), the total average movement distance of the hand unit 4 is 13
It becomes Lmax / 6, which is increased by about 8% as compared with 2Lmax of the conventional example, but since the probability that the preceding access and the subsequent access are performed is 1/2, the number of movements of the hand unit 4 at that time is 6 times. To 3 times, and the total number of movements of the hand part 4 is 9
Reduced from 6 to 6. Generally, the hand unit 4 of this embodiment
As described above, the cartridge 1 is relatively large in size, and the ratio of the time required for starting and stopping is large. Therefore, reducing the number of movements of the hand unit 4 as in this embodiment is a unit. The exchange capacity of the cartridge 1 per hour, or MTBF (Mean Time Btwee) of the hand unit 4
n advantage).

As described above, according to the library apparatus of the present embodiment, the first group G1 and the second group G2 having different transport distances from the storage section 3a of the warehouse 3 to the drive section 2 are provided.
When the new cartridge 1 is taken out from the second group G2, only the second group G2 having a long transport distance is subjected to the preceding access and the subsequent access, and when the new cartridge 1 is taken out from the second group G2, The least frequently used cartridge 1 is moved to the second group G2, and the most frequently used cartridge 1 is always transferred to the first group having the shortest transport distance.
Since they are arranged in the group G1, the average movement distance of the hand unit 4 and the number of movements can be reduced.

FIGS. 3 and 4 show a second embodiment of the present invention, in which the warehouse 3 is divided into a total of four groups having different transport distances with respect to the drive unit 2. That is, the first group G1 and the second group
There are a group G2, a third group G3, and a fourth group G4. The other structure is the same as that of the first embodiment.

The operation of the hand unit 4 will be described below with reference to the schematic configuration diagram shown in FIG. 3 and the flowchart shown in FIG. The numbers attached to the solid arrows in FIG. 3 indicate the order of operation of the hand unit 4. Further, when the cartridge 1 to be accessed next is in the first group G1 of the warehouse 3, the preceding access and the subsequent access are not performed as in the first embodiment. Will be described in the case where the group exists in the second group G2 to the fourth group G4.

First, when there is a replacement instruction of the cartridge 1 (S20), the cartridge 1 is moved to the storage portion 3a in which the next cartridge 1 is stored and the cartridge 1 is taken out, and at the same time, one empty storage portion 3a of the first group G1. Move to ‘
The cartridge 1 is stored in one empty storage portion 3a '(S21). Next, when the reading and writing of the cartridge 1 in the drive unit 2 is completed (S22), the cartridge 1 in the drive unit 2 is taken out (S23) and moved to the other empty storage unit 3a 'of the first group G1. , The cartridge 1 is stored in the other empty storage portion 3a '(S2
4). Then, one empty storage unit 3 of the first group G1
The cartridge 1 stored in a'is taken out, moved to the drive unit 2, and the cartridge 1 is loaded in the drive unit 2 (S25). At this time, if the cartridge 1 to be accessed next is present in the fourth group G4 of the warehouse 3 as shown in FIG. 3 (S26), based on the data stored in the control unit, The cartridge 1 which is least used from the inside is taken out (S27), and this is
The group G4 is stored in the empty storage section (S2).
8). After that, the cartridge 1 is moved to the second group G2, and the cartridge 1 having the lowest use frequency is taken out from the second group G2 (S29), and the cartridge 1 is stored in the empty storage section formed in the third group G3 (S30). Furthermore, the first group G1
To the first group G1 and take out the least frequently used cartridge 1 (S31), and store it in the empty storage section formed in the second group G2 (S3).
2) Return to step S1 to move to the drive unit 2 and wait until there is a next exchange command. In this process, the two empty storage portions 3a 'are secured in the first group G1 again, and this is performed by utilizing the empty time after the replacement of the cartridge. If the cartridge 1 to be accessed next is not present in the fourth group G4 (S26) and is present in the third group G3 (S33), the cartridge 1 is moved to the second group G2 and then moved to the second group G2. The least frequently used cartridge 1 is taken out of the G2 (S29), and the cartridge 1 is stored in the empty storage section formed in the third group G3 (S30). Furthermore,
The cartridge 1 which is used least frequently is taken out of the first group G1 by moving to the first group G1 (S31), and the cartridge 1 is stored in the empty storage section of the second group G2 (S32), The process returns to S1 and moves to the drive unit 2 and waits for the next exchange command. Further, the cartridge 1 to be accessed next does not exist in the fourth group G4 and the third group G3 (S26,
S33), if it exists in the second group G2 (S33)
34), move to the first group G1 and move to the first group G1
The cartridge 1 which is least frequently used is taken out of the above (S31), and the cartridge 1 is stored in the empty storage portion formed in the second group G2 (S32), and the process returns to step S1 to move to the drive portion 2 and the next. Wait until there is a replacement order.

The preceding access of this embodiment is not performed when the cartridge 1 to be accessed next is in the first group G1. On the other hand, the cartridge 1 is the second
When the hand unit 4 is present in the group G2, the hand unit 4 moves from the drive unit 2 to the cartridge 1 of the second group G2 by the average movement distance 3Lmax / 8, and then moves to the one empty storage unit 3a 'of the first group G1. It moves a distance of 2Lmax / 8 and moves to the drive unit 2 by an average moving distance Lmax / 8. Next, when the cartridge 1 exists in the third group G3, the hand unit 4 moves from the drive unit 2 to the cartridge 1 of the third group G3 in an average moving distance of 5 Lmax /
After moving by 8, the average moving distance 4Lmax / 8 is moved to one empty storage portion 3a 'of the first group G1, and the average moving distance Lmax / 8 is moved to the drive portion 2. When the cartridge 1 exists in the fourth group G4, the hand unit 4 moves from the drive unit 2 to the cartridge 1 of the fourth group G4 by the average moving distance 7Lmax / 8, and then one of the empty spaces in the first group G1. It moves to the storage part 3a 'by the average moving distance 6Lmax / 8, and moves to the drive part 2 by the average moving distance Lmax / 8.

In this access, regardless of the group in which the cartridge 1 to be accessed next was present,
The hand unit 4 moves only with respect to the first group G1.
That is, the hand unit 4 takes out the cartridge 1 from the drive unit 2 and moves to the other empty storage unit 3a 'of the first group G1 by the average moving distance Lmax / 8, and then, the one empty storage unit 3a of the first group G1. Average moving distance Lmax /
Then, the cartridge 1 to be accessed next is gripped and moved to the drive unit 2 by the average moving distance Lmax / 8.

The subsequent access is not performed when the cartridge 1 to be accessed next is in the first group G1. On the other hand, the cartridge 1 is the second group G
2 exists in the second group G2, the hand section 4 moves from the drive section 2 to the least frequently used cartridge 1 in the first group G1 by the average moving distance Lmax / 8, and then the empty storage in the second group G2. Average moving distance Lma to part 3a
Move by x / 4 and drive unit 2 average moving distance 3Lma
Move x / 8. Next, when the cartridge 1 is present in the third group G3, the hand unit 4 moves from the drive unit 2 to the least frequently used cartridge 1 in the second group G2 by the average movement distance 3Lmax / 8, The average moving distance Lmax / 4 is moved to the empty storage unit 3a of the third group G3. After that, the hand unit 4 moves to the cartridge 1 having the lowest use frequency in the first group G1 by the average moving distance Lmax / 2, and then moves to the empty storage unit 3a in the second group G2 by the average moving distance Lmax /. Four
Move only to drive unit 2 and average moving distance 3Lmax / 8
Just move. In addition, the cartridge 1 is the fourth group G
4 exists in the fourth group G4, the hand section 4 moves from the drive section 2 to the least frequently used cartridge 1 in the third group G3 by the average moving distance of 5 Lmax / 8, and then the empty storage of the fourth group G4. Average moving distance L to part 3a
Move by max / 4. After that, the hand unit 4 moves to the cartridge 1 having the lowest usage frequency in the second group G2 by the average moving distance Lmax / 2, and then moves to the third group G3.
It moves to the vacant storage part 3a by the average moving distance Lmax / 4. After that, the hand unit 4 moves to the cartridge 1 having the lowest use frequency in the first group G1 by the average moving distance Lmax / 2, and then moves to the empty storage unit 3a in the second group G2 by the average moving distance Lmax /. It moves by 4 and moves to the drive unit 2 by the average moving distance of 3Lmax / 8.

Here, assuming that the access probability to the nth group is αn, the average movement distance of the hand unit 4 in the preceding access is given by the following equation (4)
The average movement distance of the hand is calculated by the following equation (5), and the average movement distance of the hand unit 4 in the subsequent access is shown by the following equation (6).

Average moving distance in prior access (number of groups = 4) = α2 (3Lmax / 8 + 2Lmax / 8 + Lmax / 8) + α3 (5Lmax / 8 + 4Lmax / 8 + Lmax / 8) + α4 (7Lmax / 8 + 6Lmax / 8 + Lmax / 8) = 6α2Lmax / 8 + 10α3Lmax / 8 + 14α4Lmax / 8 (4) Average moving distance in this access = Lmax / 8 + Lmax / 12 + Lmax / 8 = Lmax / 3 (5) Average moving distance in subsequent access = α2 (Lmax / 8 + 2Lmax / 8 + 3Lmax / 8) + α3 (3Lmax / 8 + 2Lmax / 8) + α3 (4Lmax / 8 + 2Lmax / 8 + 3Lmax / 8) + α4 (5Lmax / 8 + 2Lmax / 8) + α4 (4Lmax / 8 + 2Lmax / 8) + α4 (4Lmax / 8 + 2Lmax / 8) + 6L14 + 22/8 + 6α2Lmax / 8 From the equation (5), the average movement distance of the hand unit 4 in this access is equal to that of the first embodiment. As compared with the case of dividing into groups is reduced by 50%. This depends on the size of the first group G1, and it can be seen that the average movement distance in this access becomes shorter in inverse proportion to the number of groups.

From the formula (4), when a plurality of cartridges 1 having continuous data are concentrated in the first group G1 and almost α1 = 1, the preceding access is not performed but each data is stored. When the cartridges 1 are uniformly dispersed and α1 = α2 = α3 = α4 = 0.25, the hand unit 4 moves about twice on average, and the average moving distance is 15Lmax / 16. .

From equation (6), the subsequent access is α1 =
1 is not performed in the state of 1, and α1 = α2 = α3 = α4 = 0.
In the state of No. 25, the hand unit 4 moves on average about four times, and the average moving distance is 21Lmax / 16.

Therefore, when the warehouse 3 is divided into a total of four groups, and when the data is concentrated and almost α1 = 1, the main access can be performed while maintaining the feature that the preceding access and the subsequent access can be omitted. The average movement distance of the hand unit 4 can be shortened by 50% as compared with the first embodiment (the number of groups = 2). Even in the worst condition where data is evenly distributed and α1 = α2 = α3 = α4 = 0.25, the total average number of movements in the process from the preceding access to the subsequent access to the subsequent access is about Since the total average moving distance is 9 times and the total moving distance is 31Lmax / 12, the performance is almost the same as that of the conventional example although the average moving distance is slightly increased.

FIG. 5 shows a third embodiment of the present invention, which is the same as the second embodiment in that the warehouse 3 is divided into a total of four groups, but in this embodiment, the drive unit 2 is used. On the other hand, the first group G1 having the shortest transport distance is composed of only two empty storage portions 3a '. The other structure is the same as that of the second embodiment.

In the preceding access of this embodiment, when the cartridge 1 to be accessed next is in the second group G2, the hand unit 4 moves from the drive unit 2 to the cartridge 1 of the second group G2 in the average moving distance Lmax. After moving by / 6, one empty storage part 3 of the first group G1
The average moving distance Lmax / 6 is moved to a ', and the average moving distance to the drive unit 2 becomes zero. On the other hand, when the cartridge 1 exists in the third group G3, the hand unit 4 moves from the drive unit 2 to the cartridge 1 of the third group G3 by the average moving distance 3Lmax / 6, and then one of the empty spaces in the first group G1. Average moving distance 3L to storage 3a '
After moving by max / 6, the average moving distance to the drive unit 2 becomes zero. When the cartridge 1 exists in the fourth group G4, the hand unit 4 moves from the drive unit 2 to the cartridge 1 of the fourth group G4 in an average moving distance of 5 Lmax /
After moving by 6, the average moving distance of 5 Lmax / 6 is moved to one empty storage portion 3a ′ of the first group G1, and the average moving distance to the drive portion 2 becomes zero.

In this access, regardless of the group in which the cartridge 1 to be accessed next was present,
The hand unit 4 moves only with respect to the first group G1.
That is, the hand unit 4 takes out the cartridge 1 from the drive unit 2 and moves to the other empty storage unit 3a 'of the first group G1, and then the one empty storage unit 3 of the first group G1.
It moves to a ', then grips the cartridge 1 to be accessed next and moves to the drive unit 2, but the average moving distances thereof are all 0 according to the assumption.

In the subsequent access, when the cartridge 1 to be accessed next is in the second group G2, the hand unit 4 moves on average from the drive unit 2 to the other empty storage unit 3a 'of the first group G1. After moving by the distance 0, it moves to the vacant storage unit 3a of the second group G2 by the average moving distance Lmax / 6, and moves to the drive unit 2 by the average moving distance Lmax / 6. Next, cartridge 1
Is present in the third group G3, the hand unit 4 moves from the drive unit 2 to the least frequently used cartridge 1 in the second group G2 by the average movement distance Lmax / 6, and then, in the third group G3. It moves to the vacant storage part 3a by the average moving distance 2Lmax / 6. Then, the hand unit 4 moves to the other empty storage unit 3a 'of the first group G1 by the average moving distance 3Lmax / 2, and then moves to the empty storage unit 3a of the second group G2 to the average moving distance Lmax / 6.
The average moving distance Lmax / 6 to the drive unit 2. Further, the cartridge 1 is the fourth group G4.
, The hand unit 4 is connected to the drive unit 2 to the third unit.
The least used cartridge 1 in group G3
After moving up to the average moving distance 3Lmax / 6, the average moving distance 2L to the vacant storage section 3a of the fourth group G4.
Move by max / 6. After that, the hand unit 4 moves to the cartridge 1 which is least frequently used in the second group G2 by the average moving distance 4Lmax / 6, and then the third group G2.
Average moving distance 2Lmax / 6 to 3 empty storage units 3a
Just move. After this, the hand unit 4 moves to the first group G1.
Average moving distance 3Lmax / 6 to the other empty storage section 3a '
After that, the average moving distance Lmax / 6 is moved to the vacant storage section 3a of the second group G2, and the average moving distance Lmax / 6 is moved to the drive section 2.

Here, assuming that the access probability to the nth group is αn, the average movement distance of the hand unit 4 in the preceding access is given by the following equation (7).
The average movement distance of the hand is calculated by the following equation (8), and the average movement distance of the hand unit 4 in the subsequent access is shown by the following equation (9).

Average moving distance in prior access (number of groups = 4) = α2 (Lmax / 6 + Lmax / 6 + 0) + α3 (3Lmax / 6 + 3Lmax / 6 + 0) + α4 (5Lmax / 6 + 5Lmax / 6 + 0) = 2α2Lmax / 6 + α3Lmax + 10α4Lmax / 6 (7) Average movement distance in this access = 0 + 0 + 0 = 0 (however, the hand unit 4 moves three times) (8) Average movement distance in subsequent access = α2 (0 + Lmax / 6 + Lmax / 6) + α3 (Lmax / 6 + 2Lmax / 6) + α3 (3Lmax / 6 + Lmax / 6 + Lmax / 6) + α4 (3Lmax / 6 + 2Lmax / 6) + α4 (4Lmax / 6 + 2Lmax / 6) + α4 (3Lmax / 6 + Lmax / 6 + Lmax / 6) = 2α2Lmax / 6 + 8α3Lmax / 6 + 16α4 This example In this case, the first group G1 is set to the empty storage section 3a '.
The average moving distance of the hand unit 4 in this access is 0, as shown in the equation (5), because it is configured only. However, the cartridge 1 stored in the first group G1
Since it is always necessary to transport the data to another group, it is possible to omit the preceding access and the subsequent access even when the data is concentrated near the drive unit 2 as in the first and second embodiments. Can not. In this embodiment, since there is no cartridge 1 resident in the first group G1, α1 = 0 is always satisfied, and when data is concentrated near the drive unit 2, α2 = 1 is satisfied.

From equations (7) and (8), when α1 = 1, the average moving distance of the hand unit 4 in the preceding access and the following access is both Lmax / 3. Therefore, when compared with the conventional example, the total average number of movements during the process from the preceding access to the subsequent access to the subsequent access remains at about 9, but the total average movement distance is 2Lmax /
3, which is about 66% reduction.

The data are evenly distributed, and α1
= Α2 = α3 = α4 = 0.25, the average movement distance of the hand unit 4 in this access is 13 Lma.
x / 9. This means that the average movement distance is slightly increased, but the performance is almost the same as that of the conventional example.

Therefore, when it is desired to minimize the time required for exchanging the cartridge 1, the first group G1 may be composed of only the empty storage portion 3a 'as in this embodiment, and the movement distance and movement of the hand portion 4 may be reduced. When it is desired to reduce the number of times, the empty storage portion 3a 'may be secured in a part of the first group G1 as in the first and second embodiments. Further, it is of course possible to set the size of the first group G1 smaller than that of the other groups so that the characteristics of the two groups are harmonized according to the purpose.

In each of the above embodiments, the optical disk is illustrated as the storage medium, but the storage medium is not limited to this, and the present invention can be applied to a magnetic disk or a magnetic tape. Further, in each of the above embodiments, the storage medium is stored in the cartridge 1, but the storage medium may be directly conveyed. Further, the warehouse for storing the storage medium may include not only the storage units arranged in the vertical direction but also the storage units arranged in the horizontal direction. In this case, the transport means is configured to move in the vertical and horizontal directions. It should have been done.

[0052]

As described above, according to the library apparatus of the present invention, it is possible to always arrange the recording media that are frequently used in order from the group having the shortest transport distance, and to store continuous data. When a plurality of recording media are concentrated in the vicinity of the drive unit, the operation of the conveying means can be extremely reduced, so that the average moving distance of the conveying means and the number of movements can be shortened. The exchange capacity of the medium can be significantly improved. In this case, the average transport distance until an arbitrary recording medium is loaded into the drive unit decreases in inverse proportion to the number of groups in the warehouse, and even with the smallest configuration in which the groups are divided into two, the average of the transport means is smaller than that of the conventional example. The travel distance can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a library device showing a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the hand unit.

FIG. 3 is a schematic configuration diagram of a library device showing a second embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the hand unit.

FIG. 5 is a schematic configuration diagram of a library device showing a third embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a library device showing a conventional example.

[Explanation of symbols]

1 ... Cartridge, 2 ... Drive part, 3 ... Warehouse, 3a ...
Storage part, 3a '... Empty storage part, 4 ... Hand, G1 ... First
Group, G2 ... second group, G3 ... third group,
G4 ... Group 4.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyoshi Izawa 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Claims] 1. A warehouse having a large number of storage units, a large number of recording media stored in the storage units of the warehouse, a drive unit for writing and reading data to and from the recording media, and a recording medium loaded in the drive units. In a library device provided with a transport means for exchanging the storage medium with an arbitrary recording medium stored in a warehouse, and dividing each storage portion of the warehouse into at least two or more groups having different transport distances with respect to the drive portion. At least two empty storage units are provided in a group having the shortest transport distance, and when exchanging the recording medium by the transport unit, after storing an arbitrary recording medium in the warehouse in one empty storage unit, The recording medium in the empty section is accommodated in the other empty accommodation section and the recording medium in the one empty accommodation section is conveyed to the drive section, and the recording medium has the shortest conveyance distance. If it is stored in a group other than the group, the recording medium with the lowest usage frequency is used from each group from the group having the next shortest transport distance to the group having the shortest transport distance with respect to the group containing the recording medium. A library device, wherein the library device is configured to be sequentially moved to a group having a longer transport distance.