JPH07160438A - Library device - Google Patents

Abstract

PURPOSE:To provide a library device which interchanges recording media in an extremely short time. CONSTITUTION:When a cartridge 1 is replaced, the cartridge 1 which is taken out of a drive part 2 is stored in a free storage part 3a' of a 1st group G1 close to the drive part 2 and then a specified cartridge 1 is taken out of the 1st group G1 or a 2nd group G2 and loaded in the drive part 2, so that the cartridge 1 in the drive part 2 can be replaced in an extremely short time. Further, when the new cartridge 1 is taken out of the 2nd group G2, the cartridge 1 of the lowest use frequency in the 1st group G1 is moved from the 2nd group G2 far from the drive part 2 to secure a new free storage part 3a' in the 1st group G1, and, then cartridges 1 of high use frequency are arranged in the 1st group G1 which is short in conveyance distance at all times and the mean movement distance of a hand part 4 is greatly shortened.

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. The optical disc library device stores a large number of standard cartridges each storing one optical disc medium in a warehouse, and moves the optical disc cartridges to an optical disc drive by an automatic handling mechanism.
It is configured to read / write data from / to the optical disc medium in the optical disc cartridge.

Normally, when the cartridge is replaced, FIG.
As shown in FIG. 4, the cartridge 1 is transferred from the drive unit 2 to the warehouse 3 by using the hand unit 4 forming a part of the automatic handling mechanism.
Of the cartridge 1, the hand portion 4 is moved to the storage portion 3a of the arbitrary cartridge 1, and finally the cartridge 1 is transported to the drive portion 2.

[0005]

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 in the warehouse 3 and then convey the arbitrary cartridge 1 accommodated in the warehouse 3 to the drive unit 2. Therefore, the conventional optical disk library device has a problem that the average access time reaches ten and several seconds when the replacement of the cartridge 1 is included.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a library apparatus which can replace a recording medium in an extremely short time.

[0007]

In order to achieve the above-mentioned object, the present invention provides, in claim 1, a warehouse having a large number of storage sections, a large number of recording media stored in the storage sections of the warehouse, and a recording medium. In a library device including a drive unit for writing and reading data to and from the storage unit, and a transporting 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 The drive unit is divided into at least two groups having different transport distances, and at least one empty storage unit is provided in the group having the shortest transport distance. After storing the above recording medium in the empty storage section, any recording medium in the warehouse is conveyed to the drive section, and this recording medium has the shortest conveying distance. If it is stored in a group other than the group, the recording medium with the lowest usage frequency is transferred from the group with the shortest transport distance to the empty storage section created in that group, and the empty storage area is stored again in the group with the shortest transport distance. It is configured to secure a section.

According to a second aspect of the present invention, in the library apparatus according to the first aspect, the frequency of use of the recording medium is set based on the number of times the recording medium has been used within a predetermined time and the elapsed time after use. .

[0009]

According to the library apparatus of claim 1, when the recording medium is exchanged by the conveying means, after the recording medium in the drive section is accommodated in the empty accommodation section provided in the group having the shortest conveyance distance, Since any recording medium in the warehouse is conveyed to the drive unit, a new recording medium is loaded in the drive unit in an extremely short time. Also, if a new recording medium is stored in a group other than the group with the shortest transport distance, the recording medium with the lowest use frequency from the group with the shortest transport distance is stored in the empty storage section that occurred in that group. After the transfer, the empty storage section is secured again in the group having the shortest transport distance. As a result, the frequently used recording media are always arranged in the group having the shortest transport distance, and the average travel distance of the transport means is shortened.

According to the library apparatus of claim 2, in addition to the effect of claim 1, the frequency of use of the recording medium is set based on the number of times the recording medium is used within a predetermined time and the elapsed time after use. Therefore, the recording medium used once stays in the group having the shortest transport distance within a certain period of time, and the next loading to the drive unit is performed in a short time.

[0011]

1 to 3 show a first embodiment of the present invention, and FIGS. 1 and 2 are schematic block diagrams of a library apparatus. This library device has 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 unit together with a moving mechanism and a control unit (not shown).

The cartridge 1 accommodates an optical disk as a recording medium, and by being loaded in the drive unit 2, it becomes accessible to the drive unit 2.

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 sections 3a arranged vertically, and each storage section 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. Also, one empty storage portion 3a 'is 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 apparatus constructed as described above, the cartridge 1 in the drive unit 2 is exchanged with the arbitrary cartridge 1 in the warehouse 3 by the hand unit 4. The operation of the hand unit 4 will be described below with reference to the schematic configuration diagram shown in FIGS. 1 and 2 and the flowchart shown in 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 a replacement instruction for the cartridge 1 (S1), the cartridge 1 in the drive unit 2 is taken out (S2), and the cartridge 1 is moved to the vacant storage unit 3a 'of the first group G1 of the warehouse 3 and the cartridge 1 Empty storage section 3a '
(S3). Next, the designated cartridge 1 is moved to the accommodating portion 3a in which it is accommodated, the cartridge 1 is taken out of the accommodating portion 3a, moved to the drive portion 2, and the cartridge 1 is loaded into the drive portion 2 (S4). Here, the drive unit 2 writes or reads data to or from the new cartridge 1. That is, the operation up to this point is the access time. Next, as shown in FIG. 1, the designated cartridge 1 is the first group G of the warehouse 3.
If it exists in S1 (S5), the process returns to step S1 to move to drive unit 2 and wait until there is a next exchange command. Further, as shown in FIG. 2, if the designated cartridge 1 does not exist in the first group G1 (S5), that is, if it exists in the second group G2, based on the data stored in the control unit. The cartridge 1 having the lowest use frequency is taken out of the first group G1 (S6), and the empty cartridge of the second group G2, that is, step S4.
The cartridge 1 taken out in step S1 is stored in the storage portion 3a (S7), and the process returns to step S1 to move to the drive portion 2 and wait until there is a next replacement instruction. In this process, the empty storage portion 3a 'is secured again in the first group G1, and the rearrangement process of the cartridge 1 is completed. This is done using the free time after the cartridge is replaced. As a result of such rearrangement processing, the cartridges 1 that are frequently used are always arranged in the first group G1 that has a short transport distance with respect to the drive unit 2.

Next, the average access time 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.

First, in the conventional example, as shown in FIG. 6, in the process of returning the cartridge 1 in the drive section 2 to the predetermined storage section 3a, the predetermined storage section 3a for storing the cartridge 1 is provided from one end of the warehouse 3 to another. Since the edges are present with an average probability, the average movement distance of the hand unit 4 is Lmax / 2.
Next, the hand unit 4 moves toward the storage unit 3a in which the arbitrary cartridge 1 is stored. In this case, the hand unit 4
Will move between any two storage units 3a of the warehouse 3, and the movement distance of the hand unit 4 at that time will be approximately Lmax / 3 (for example, "real time"; J. Martin, stable translation by Kitahara, See P546 etc.). Lastly, the hand unit 4 conveys the cartridge 1 from the storage unit 3a to the driver. Since this process is the same as the case of storing the cartridge 1 in the warehouse 3, the average access distance is Lmax / 2. Therefore, by the time the data can be written to or read from the recording medium in the cartridge 1 after replacement, at least the hand unit 4 has an average of 4Lmax / 3 as shown in the following formula (1). Will move.

Average moving distance at the time of access = Lmax / 2 + Lmax / 3 + Lmax / 2 = 4Lmax / 3 (1) On the other hand, in the present embodiment, as shown in FIG. Since it is stored in the empty storage section 3a 'having the shortest access distance, the moving distance of the hand section 4 at this time is zero. Further, the process of moving the hand unit 4 toward the storage unit 3a storing the arbitrary cartridge 1 and carrying the designated cartridge 1 to the drive unit 2 is the same as the process of carrying the cartridge 1 to the drive unit 2 in the conventional example. Therefore, the average movement distance of the hand unit 4 at this time is Lmax / 2 for both going and returning. Therefore,
In the present embodiment, the hand unit 4 moves only Lmax on average by the time data can be written or read from the recording medium of the cartridge 1 after replacement,
The average access time is reduced by about 25% as compared with the conventional example.

Further, in the present embodiment, the unnecessary cartridge 1 is first stored in the empty storage portion 3a 'of the first group G1 having a short transport distance. In this case, since the empty storage portion 3a 'of the first group G1 is not designated with a specific position, the average movement distance of the hand portion 4 at this time is Lmax / 4.
Becomes Next, the arbitrary cartridge 1 is the first group G
Drive unit 2 selected from the first or second group G2
When the selected cartridge 1 is present in the first group G1 when being conveyed to, the hand unit 4 moves between any two points in the first group G1 by the average moving distance Lmax / 6, The specified cartridge 1 is gripped and moved to the drive unit 2 by the average moving distance Lmax / 4. At this point, the empty storage portion 3a 'is secured in the first group G1, so that the rearrangement process of the cartridge 1 is not performed. When the selected cartridge 1 is present in the second group G2, the designated cartridge is taken out from the second group G2 and conveyed to the drive unit 2, and then the rearrangement process of the cartridge 1 is performed. . Here, the hand unit 4 is the empty storage unit 3 of the first group G1.
The average moving distance Lmax / 2 from the position where a'is present to the storage position of the designated cartridge 1 in the second group G2.
And the cartridge 1 is gripped and moved to the drive unit 2 by an average movement distance of 3 Lmax / 4, and further, the cartridge 1 of the first group G1 that is least frequently used.
After moving the average moving distance Lmax / 4 to the storage position of
The cartridge 1 is gripped and moved by the average moving distance Lmax / 2 to the empty storage portion formed in the second group G2. Then, after storing the cartridge 1 in the second group G2,
It moves to the drive unit 2 by the average moving distance 3Lmax / 4 for the next cartridge replacement.

Here, the designated cartridge 1 is the first
The probability of existence in the group G1 is α1 (1 ≧ α1 ≧ 0.
5) Assuming that the probability of being present in the second group G2 is 1-α1, the average movement distance until the hand portion 4 loads the designated cartridge 1 into the drive portion 2 is represented by the following equation (2).

Average moving distance during access (number of groups = 2) = Lmax / 4 + α1 (Lmax / 6 + Lmax / 4) + (1-α1) (Lmax / 2 + 3Lmax / 4) = 3Lmax / 2-5α1 · Lmax / 6 ( 2) At this time, the related data has a plurality of specific cartridges 1
(Α1 = 1), all the specified cartridges 1 are present in the first group G1, and therefore the movement distance of the hand unit 4 is 2 · Lmax / 3 from the equation (2). About 50% compared to the conventional case shown in (1)
Shortened.

Further, assuming that the data is completely dispersed and is not concentrated on a specific plurality of cartridges 1 (α
1 = 0.5), the movement distance of the hand unit 4 is 13 · Lmax / 1
2, which is about 25% shorter than the conventional case. Such shortening of the movement distance is achieved as a result of storing the unnecessary cartridge 1 in the empty storage portion 3a ′ in the vicinity of the drive portion 2 in the process of replacing the cartridge 1 and causing the designated cartridge 1 to be conveyed first. It is what is done.

Further, in this embodiment, when the designated cartridge 1 exists in the second group G2 as shown in FIG. 2, the rearrangement process of the cartridge 1 is performed. Here, as the rearrangement processing, after the designated cartridge 1 is transported to the drive unit 2, the least frequently used cartridge 1 in the first group G1 is transported to the empty storage unit generated in the second group G2. The average movement distance of the hand unit 4 at this time is expressed by the following equation (3).

Average moving distance in rearrangement (number of groups = 2) = (1-α1) (Lmax / 4 + Lmax / 2 + 3Lmax / 4) = (1-α1) · 3Lmax / 2 (3) Here, the related data is Specific multiple cartridges 1
If it is concentrated in 1 and becomes almost α1 = 1,
The least used cartridge 1 in group G1
The rearrangement process for transporting the sheet to the second group G2 becomes almost unnecessary. Even when the data is evenly distributed to the cartridges 1 and α1 = 0.5, the hand unit 4 moves only 1.5 times on average, and the average moving distance at that time is 3Lmax. This is / 4, which is almost the same distance as when the designated cartridge 1 is transported. Normal,
Since these rearrangement processes are executed by utilizing the free time after the replacement of the cartridge, they do not cause the average access performance of the library device to deteriorate.

By the way, in the above embodiment, the cartridge 1 is used.
The frequency of use of the cartridge 1 is determined based on the number of times the drive unit 2 is loaded within a predetermined time. The frequency of use is determined by the number of times the cartridge 1 is loaded in the drive unit 2 within a predetermined time, and There is also a method of obtaining it as the sum with the frequency determined by the elapsed time after being taken out from 2. The setting of the use frequency determined only by the number of times the cartridge 1 is loaded in the drive unit 2 is suitable when the cartridge 1 is accessed in a relatively constant cycle. For example, observation data is accumulated every certain time. , Effectively works when accumulating monitoring data. However, when the start time of the service is limited as in the ticket sales service and the same data stored in the recording medium of a specific cartridge 1 is used temporarily in a concentrated manner, it is accessed once. The probability that the cartridge 1 will be accessed again within a short time is extremely high. Therefore, the usage frequency is the sum of the frequency determined by the number of times the cartridge 1 is loaded in the drive unit 2 within a predetermined time period and the frequency determined by the elapsed time after the cartridge unit 1 is removed from the drive unit 2 to access once. If the cartridge 1 is kept in the first group G1 for a certain period of time, the next time the drive unit 2 is loaded, the average of the hand unit 4 during the intensive use of the same data is achieved. The moving distance can be shortened. In this case, the frequency determined by the elapsed time after being taken out from the drive unit 2 may be set to be higher as the elapsed time is shorter.

As described above, according to the library apparatus of this embodiment, when the cartridge 1 is replaced, the cartridge 1 taken out from the drive unit 2 is stored in the empty storage unit 3a 'of the first group G1 near the drive unit 2. After that, the designated cartridge 1 is taken out from the first group G1 or the second group G2 and loaded into the drive unit 2, so that the cartridge 1 in the drive unit 2 can be replaced in an extremely short time. When a new cartridge 1 is taken out from the second group G2, the least frequently used cartridge 1 in the first group G1 is moved to the second group G2 farthest from the drive unit 2 and is transferred to the first group G1. Since the new empty storage section 3a 'is secured, the frequently used cartridges 1 can always be arranged in the first group G1 having a short transport distance, and the average movement distance of the hand section 4 is greatly shortened. be able to.

When it is assumed that the cartridge 1 is conveyed to the plurality of drive units 2 by one hand unit 4 and the replacement frequency of the cartridge 1 is temporarily increased, the first group G1 is set. A plurality of empty storage portions 3a '
Is provided, and the designated cartridge 1 is conveyed a plurality of times, and then the rearrangement process is collectively executed.

FIGS. 4 and 5 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. 4 and the flowchart shown in FIG. The numbers attached to the solid arrows in FIG. 4 indicate the order of operation of the hand unit 4.

First, when there is an instruction to replace the cartridge 1 (S10), the cartridge 1 in the drive unit 2 is taken out (S11), and the cartridge 1 is moved to the vacant storage unit 3a 'of the first group G1 of the warehouse 3 and the cartridge 1 Empty storage section 3
It is stored in a '(S12). Next, the cartridge 1 is moved to the storage unit 3a in which the designated cartridge 1 is stored, the cartridge 1 is taken out from the storage unit 3a, moved to the drive unit 2, and the cartridge 1 is loaded in the drive unit 2 (S1).
3). Here, the drive unit 2 writes or reads data to or from the new cartridge 1. That is, the operation up to this point is the access time. Next, if the cartridge 1 designated as shown in FIG. 4 exists in the fourth group G4 of the warehouse 3 (S1
4) Based on the data stored in the control unit, the least frequently used cartridge 1 is taken out of the third group G3 (S15), and the cartridge 1 is stored in the empty storage unit of the fourth group G4 (S16). ). After this, the second group G
The cartridge 1 is moved to 2 and the least frequently used cartridge 1 is taken out of the second group G2 (S17), and the cartridge 1 is stored in the empty storage section of the third group G3 (S18).
Further, the cartridge 1 which is used least frequently is taken out from the first group G1 by moving to the first group G1 (S19), and the cartridge 1 is stored in the empty storage section formed in the second group G2 (S20). , And returns to step S1 to move to the drive unit 2 and wait until there is a next exchange instruction. In this process, the empty storage unit 3 is again added to the first group G1.
a'is secured, and the relocation process of the cartridge 1 is completed. This is done using the free time after the cartridge is replaced. If the designated cartridge 1 exists in the third group G3 (S14, S21), the process proceeds to step S17, and by the operations of steps S17 to S20, the second group G2 is changed to the third group G3. Rearrangement and rearrangement from the first group G1 to the second group G2 are performed, and the process returns to step S1 to move to the drive unit 2 and wait. On the other hand, if the designated cartridge 1 is present in the second group G2 (S14, S21, S
22), the process proceeds to step S19, the rearrangement from the first group G1 to the second group G2 is performed by the operations of steps S19 and S20, and the process returns to step S1 to move to the drive unit 2 and wait. If the designated cartridge 1 does not exist in the second to fourth groups G2, G3, G4 (S14, S21, S22), that is, if it exists in the first group G1, the cartridge 1 Without performing the rearrangement process, the process returns to step S1 to move to the drive unit 2 and wait. As a result of such rearrangement processing, the cartridges 1 are arranged in the drive unit 2 in the order of high use frequency from the first group G1 having the shortest transport distance.

Here, when the access probability to the nth group is αn, the average moving distance until the hand unit 4 loads the designated cartridge 1 into the drive unit 2 is given by the following equation (4).
It is represented by.

Average moving distance during access (number of groups = 4) = Lmax / 8 + α1 (Lmax / 12 + Lmax / 8) + α2 (Lmax / 4 + 3Lmax / 8) + α3 (Lmax / 2 + 5Lmax / 8) + α4 (3Lmax / 4 + 7Lmax / 8) = (3 + 5α1 + 15α2 + 27α3 + 39α4) ・ Lmax / 24 (4) At this time, the related data is a plurality of specific cartridges 1
It can be seen that when the concentration is concentrated in 1 and approximately α1 = 1, the moving distance of the hand unit 4 becomes Lmax / 3, which is shortened by about 75% as compared with the conventional case.

Even assuming that the data are uniformly distributed (α1 = α2 = α3 = α4 = 0.25), the moving distance of the hand unit 4 is 49Lmax / 48, which is a comparison with the conventional case. It can be seen that it is reduced by about 30%.

In the present embodiment as well, the rearrangement process of moving the cartridge 1 to each group in the order of frequency of use is performed, and the average movement distance of the hand unit 4 at that time is represented by the equation (5).

Average moving distance in rearrangement (number of groups = 4) = α2 (Lmax / 8 + Lmax / 4 + 3Lmax / 8) + α3 (3Lmax / 8 + Lmax / 4) + α3 (Lmax / 2 + Lmax / 4 + 3Lmax / 8) + α4 (5Lmax / 8 + Lmax / 4) + α4 (Lmax / 2 + Lmax / 4) + α4 (Lmax / 2 + Lmax / 4 + 3Lmax / 8) = 6α2Lmax / 8 + 14α3Lmax / 8 + 22α4Lmax / 8 (5) At this time, a plurality of cartridges 1 in which related data are specific
In the case where .alpha.1 = 1, the rearrangement process of the cartridge 1 is almost unnecessary, but the data are evenly distributed to each cartridge 1, and .alpha.1 = .alpha.2 = .alpha.
When 3 = α4 = 0.25, the hand unit 4 moves about 4 times on average, and the average moving distance at that time is 21 Lma.
It becomes x / 16.

Although the optical disk is exemplified as the storage medium in the above embodiment, the present invention is not limited to this, and the present invention can be applied to the one using a magnetic disk, a magnetic tape or the like. 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.

[0039]

As described above, according to the library apparatus of claim 1, when the recording medium is exchanged, the recording medium taken out from the drive unit is vacantly stored in the group having the shortest transport distance with respect to the drive unit. Since it is accommodated in the drive unit, the recording medium in the drive unit can be replaced in an extremely short time. If a new recording medium is taken out from a group other than the group with the shortest transport distance, the recording medium with the lowest frequency of use is selected from the group with the shortest transport distance to the group with the longest transport distance to the drive unit. Since the recording medium is frequently moved to the recording medium, the frequently used recording medium can be always arranged in a group having a short transport distance. 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 minimum configuration in which the groups are divided into two, the average transport distance of the transport means is reduced compared to the conventional example. It can be greatly shortened.

According to the library apparatus of claim 2, the effect of claim 1 can be achieved, and the frequency of use of the recording medium is determined based on the number of times the recording medium is used within a predetermined time and the elapsed time after use. By setting it, the used recording medium stays in the group with the shortest transport distance within a certain period of time, so that it can be loaded into the drive unit next time in a short time and stored in a specific recording medium. It is advantageous when the same data is used intensively.

[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 schematic configuration diagram of a library device showing another operation example.

FIG. 3 is a flowchart showing the operation of the hand unit.

FIG. 4 is a schematic configuration diagram of a library device showing a second embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the hand unit.

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.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masahiro Ueno 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (2)

[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 apparatus provided with a transport means for exchanging any recording medium stored in a warehouse, each storage section of the warehouse is divided into at least two groups having different transport distances with respect to the drive section,
At least one empty storage unit is provided in the group having the shortest transport distance, and when exchanging the recording medium by the transport unit, after storing the recording medium in the drive unit in the empty storage unit, any storage medium in the warehouse is stored. If this recording medium is transported to the drive unit and is stored in a group other than the group with the shortest transport distance, the least frequently used recording is made from the group with the shorter transport distance in the empty storage unit created in that group. A library apparatus, wherein the empty storage section is again secured in the group having the shortest transport distance by moving the medium. 2. The library apparatus according to claim 1, wherein the frequency of use of the recording medium is set based on the number of times the recording medium is used within a predetermined time and the elapsed time after use.