Effective utilizing method of demountable data recording medium

[Detailed Description of the Invention]

A. Field of the Invention The present invention relates to the directions of the efficient data recording medium in a data processing system. In more detail, the present invention relates to the method for decreasing spanning of a recording medium in order to raise the possibility of a copy of a recording medium. B. The former and art A present-day computer needs a host processor including one or more central processing units and one memory mechanism. A processor deals with the data memorized in the memory according to the command given to it. Therefore, the memory must have the capability to memorize the data which a processor needs, and the capability to transmit the data to a processor at the speed which can make all the operations of a computer realizable. Therefore, the cost and performance of a computer memory are deterministically [ for a commercial success of computer systems ] important. Since today's computer needs a lot of storage-of-data capacity, the computer memory of much form can be used. Although it is a high speed, the memory of an expensive form is a main memory unit, and comprises a microchip typically. A memory of form in which other use is possible is known as a peripheral storage. A magnetic direct access storage facility (DASD), a magnetic tape storage, an optical recording device and magnetism, or an optical bulk store library is included. these -- others -- as for the memory of form, in size, memory density comes from a main memory unit, respectively -- < -- the Si It was -- it is cheaper. However, other storage devices of these do not bring about the performance supplied by the main memory unit. For example, time taken to equip a tape drive, DASD1, or optical disc drive mechanism with a tape or a disk, The time taken to put a tape or a disk on the right position under reading / write-in mechanism of drive mechanism does not become as compared with a data transfer rate electronic to purity with an early main memory unit. It is not efficient to memorize all the data of computer systems to the storage device of only one form. If cost becomes it high to memorize all the data to a main memory unit too much and all the data is memorized to one of the peripheral storages, performance will fall. Typical computer systems contain both a main memory unit and the peripheral storage of one or more forms arranged as data storage hierarchy. Data storage hierarchy's arrangement is adjusted according to a user's performance and the requirements for cost. To such a hierarchy, a main memory unit is often called primary data storage equipment, and the next level of a hierarchy is often called secondary data storage equipment, and is the same as that of the following. Generally, memory density is the minimum and performance and the cost of the record level of a hierarchy are the highest. Generally memory density increases, generally performance falls, and, generally cost falls as a hierarchical level falls. By transmitting data between the levels from which a hierarchy differs if needed, the cost of a memory becomes the minimum and performance becomes the highest. Therefore, data is memorized by the main memory unit only when it is expected that a processor needs it. The hierarchy can take much form and can carry out transmission of the data directly between two arbitrary different memory levels including arbitrary numbers of data storage equipment, or the level of a memory. A well-known input-and-output channel, control device, or cache memory can be used for transmission of data by this technical field. Various art for raising the operating efficiency of l or a plurality of components of data storage hierarchy is known. 1 set of such art is known for data "shortening" and the same name. A term called shortening has been used in the sense of many as what points out the method for memorizing data efficiently and transmitting it. Using the bit of the required minimum number, one form of shortening improves data modification by expressing the character coded universally. From this required minimum number, many bits may be used and the coded lower character of universality may be expressed. Generally, the bit of the minimum number can be used for this shortening art, and it can code a fixed quantity of given information. There is shortening of another form used frequently by datacode-ization with a method which removes a non-changing bit. Since shortening of this form is called run length restriction (RLL) coding, it replaces the string of the same bit by a number of a bit of simple 2 Advance indication to repeat. One example of such art is indicated by the U.S. Pat. No. 4675750 specification. The above-mentioned patent indicates a video compression system which is memorized by magnetic tape and including removal of an excessive bit. Another data shortening art is removal of invalid data. Since the recorded data may contain the invalid data which needs to be corrected later using an error editing code, in order to memorize data, much storage-of-data space may be needed for data from the case of being errorless. The art of removing invalid data from a data set to an IBM technical disclosure bull ten, Vol.24, No.9 (February, 1982), and p.4483 is indicated. This art includes invalid data being disregarded and copying only the valid data of a data set, when a threshold with the size of this data set is reached. Therefore, the capacity of memory space required to memorize such data decreases. Another shortening art saves memory space by using the fragmented memory space. The intact portion of the recording medium which produces fragmentation from frequent access to the data set on a recording medium is said. Various fields of a recording medium can be eliminated while in use, or it can remove from use by the other methods. However, it is sometimes difficult for each continuous intact record space on a recording medium to be very small, and to record one data set there completely. A data set is copied to other media from a certain recording medium, and the shortening art which can accumulate some intact record regions to t continuous big record space is known. A U.S. Pat. No. 3787827 specification inspects a recording medium periodically, and is indicating the data recording system called finding the intact space in it. It is secured by such inspection that the intact region in a recording medium is eventually used. l more shortening art is blocking. Blocking is using an entity possible [ single transmission ] or recordable combining two or more logical records. This single Work tee tee is usually called a block. By blocking, the number between many records which exist between records, or of the gaps between Brosoku decreases, and they can distinguish now mutually. Blocking attains L, The, and higher storage density at the sacrifice of the capability to access a logical record separately. Such an example of l of blocking art is shown in the U.S. Pat. No. 3821703 specification. It aims at that all the above-mentioned data shortening art reduces the quantity of storage-of-data space required to record a specific quantity of information. If data is transmitted by a contracted form, a data transfer rate can be raised. Since one of the above-mentioned art is expressed and a term called shortening is used roughly, It will be used for pointing out the above-mentioned arbitrary art of saving storage-of-data space by removing a gap, the empty field, redundant data, or unnecessary data for a "compressive" term, for example, and short-Nuclear(ing) a record or the length of a block from now on. The penalty at the time of using a data compression is an overhead required the compressed type from an incompressible form, or in order [ its ] to change conversely about data. Logic required for compression and compression release of data can be provided in a host processor. If compression and compression release of data are performed on the level of a host processor though regrettable, the capability for a host processor to do the usual responsibility will decline. Therefore, logic required for compression and compression release of data may be provided in the control mechanism of a peripheral storage, and it may move from a host processor to a peripheral storage except for the responsibility for a data compression and compression release. The data processing system which put the responsibility for a data compression and compression release on the exterior of a host processor, It is shown in an IBM technical bull ten, Vo l.22, No.9 (February, 1980), pp.4191~4193, an IBM technical bull ten, Vo l.28, No.3A (August, 1983), and I.1281. When moving the responsibility for a data compression to the control mechanism of a peripheral storage, two problems occur. The 1st problem relates to a possibility that a recording medium can be copied to other recording media. For example, IBM3 whose written storage capacity of a tape cartridge is 200 M bytes 4 8 0 magnetic tape handlers are considered. The exact length of the tape wound around the tape cartridge can be specified only within specific tolerance on the character of a tape cartridge production process. Therefore, the actual storage capacity of a tape cartridge has a thing large more slightly than 200 M bytes. When a possibility that data can be copied to other single cartridges from a certain cartridge should be guaranteed, it is required to restrict all the data recorded on the tape cartridge to it of the minimum data volume on a cartridge. When data is recorded until the real capacity of the cartridge exceeded the limit (a tape stops remaining), Becoming [ to record 200 M bytes or more on a cartridge ] possible, it becomes impossible to copy to other tape cartridges in which only the capacity of 200 M bytes has all the contents of this tape cartridge. A similar problem may occur also with the data recording medium of other forms. Two art can be used in order that the quantity of the data recorded on a recording medium may not exceed the minimum quantity of the guaranteed storage-of-data capacity. The 1st art inspects physically the recording medium of which was used during record. Such art may produce a heavy overhead or sacrifice of being inaccurate. For example, a motion of a tape is controlled by a magnetic tape handler using a tachometer etc., and pursuing the tape length on a specific tape reel is known. The example of the art of inspecting physically the recording medium of which having been used during record is indicated by U.S. Pat. No. 4125881 and the specification of No. 4811132. The art for determining physically the data recording medium of which was recorded, though regrettable is not so exact as it is sufficient for it being reliable about all the examples of application. Another method that the data more than the minimum capacity of a specific recording medium is made not to be recorded includes supervising data at the time of record. In the data processing system transmitted or memorized with an incompressible form, data can trust such art. When data is written in a recording medium, it is supervised and the quantity of the whole data recorded on each medium is recorded. Since data is not compressed, the quantity of the recorded data is correlated with the quantity of the data which is visible to both a host processor and a memory storage control mechanism. However, it is necessary to get to know the quantity of the data recorded with the compressed type in the data processing system which compresses data. When data is compressed within a host processor, there is no between blood. It has the ability for the storage-and-file-management software which moves within a host processor to supervise the quantity of the data which could access the compressed type day evening, therefore was memorized with such a compressed type. However, as for it, in many present-day data processing systems, the overhead relevant to the data compression in the level of a host processor turns out that cost becomes high too much. As mentioned above, the performance of a host processor improves by moving from a host processor to a peripheral storage control mechanism except for the responsibility which compresses data. In Toward" D, the performance of a host processor not only carries out, but by such off-road one, compression and compression release of data become transparent for a host processor. As long as each peripheral storage data connected to the single host processor is returned to a host processor with an incompressible form, other compression algorithms may be used with the device. C. Object of the Invention The storage-and-file-management software which operates in a host processor is unable to get to know the quantity of the data memorized with the compressed type on the recording medium in memory storage in the data processing system which compresses within a memory storage control mechanism. The compressed type data in a host processor is unable to determine an exact quantity of the recording-medium space which "it being visible", however storage-and-file-management A shift wear take to memorize data to Pressure Jil[as storage-and-file-management software. Since the amount of presumed compression was not exact in fact when it only recorded until a specific quantity of incompressible form data was recorded, the minimum tape capacity may have been exceeded. If the counter in a memory storage control mechanism is used, it is possible to supervise the quantity of the data recorded with the compressed type. However, the cost of a Rioba head attaches Ya highly searching such compressed data from the counter in a memory storage control mechanism regularly to a host processor so that storage-and-file-management software can access. Therefore, the method of supervising correctly the quantity of the compressed data memorized by the recording medium by the overhead of the minimum host processor is searched for. Other problems relevant to a data compression are spanning of a recording medium. Generally Sepang of the data cent is carried out over a plurality of recording media, Since a plurality of data seeking is needed on the recording medium when wearing of a plurality of recording media is needed for calling the data set or it is already equipped with all the required recording media, avoiding is desirable. When data is simply written in to the termination of a recording medium and the termination of a recording medium is reached, if required, carrying out Sepang of the data set over a plurality of recording media is known. however, the necessity of avoiding spanning of a storage since the library of the current data recording medium is large -- I will -- it is becoming important. It is since it became a custom to compress data on the level of a memory storage control mechanism, It is becoming increasingly difficult to predict the likelihood for which it is necessary to carry out Sepang of the data set over a plurality of recording media by the host processor overhead of the minimum quantity before data recording. The key objective of the present invention is how to have been improved for removing in a data processing system and using a formula data recording medium efficiently. Other objects of the present invention are the minimum host Brothosa overheads, and are the methods for improving a possibility which carries out a data compression on the level below a host processor that a recording medium can be copied in a data processing system. Other objects of the present invention are the minimum host processor overheads, and are how to have been improved for decreasing recording-medium spanning of the data set within a data processing system that a data processing system compresses data on the following levels from a host processor. Other objects of the present invention are data processing systems including how to have been improved for improving a possibility that a recording medium can be copied and decreasing the above-mentioned recording-medium spanning. D. Means for solving problem All the above-mentioned objects of the present invention are achieved with the monitor method performed by storage-and-file-management software. In order to improve a possibility that a recording medium can be copied, without increasing a host processor overhead, the control mechanism which looks at compressed data is inspected only at the time of record of the incompressible data of the specified quantity. The quantity of the incompressible data recorded can carry out surveillance directly in a host processor. When the incompressible data of the specified quantity is recorded, the compression ratio of a data set is calculated, and record of the compressed type remaining data is supervised using it. Presumption of the minimum storage capacity of the specified quantity of the compressed data which it is going to record, i.e., a recording medium, will start record on a new recording medium. This method of decreasing recording-medium spanning, without increasing a host processor overhead, Whether record is continued by the same cartridge or it memorizing to a new cartridge using inspecting the counter within a memory storage control mechanism only at the time of the completion of record of the one whole data set and the incompressible size of the following data set which it is going to record, and the thing for which it opts are included. When the sum total of the compressed data of the recorded known and the incompressible data which it is going to record exceeds the target capacity of a recording medium, a new recording medium is inserted and the data set is recorded on a new medium. The above-mentioned method can compensate the inaccuracy of the data brought about by a control mechanism counter. E. EXAMPLE It explains as a thing which has a plurality of peripheral data storage equipment which has various forms and capability for the present invention and to carry out by multi-host processor data processing environment. Please understand that the present invention has a small number of peripheral data storage equipment comparatively, or can carry it out also in a single host processor environment with various kinds of system structures. With reference to Drawing 3, the data processing system in multi-host environment is explained. This system contains two or more host processors (host processor 10 and host processor 11 are shown in a figure) in which each contains the usual component part of a host processor, such as an operation logic mechanism, a main memory unit, and an input-and-output channel (not shown). A unit processor or a multiprocessor may be sufficient as each host processor. Although a host processor uses various operating systems, they are not important for understanding the present invention. There is a computer program which uses the present invention in each host processor so that it may explain in full detail later. Host processor 10111 is connected to common DASD12. Common DASD12 (direct access storage facility) consists of a highly efficient disk type storage. Common DASD 1 The control data structure (not shown) desirable when running a storage-of-data control program to 2, in order to adjust operation of host processors 10 and 11 to it is memorized. Highly efficient DASD14 LO DASD is received in order to memorize the data set in which direct access is carried out by host processors 10 and 11 and to memorize the data set generated by host processors 10 and 11. Low performance DASD15 LI DASD memorizes the data set whose frequency direct access is carried out [ frequency ] by host processors 10 and 11 is lower than what is memorized by highly efficient DASD14. DASD 1 If the data memorized by 4 ages since it was not accessed by host processors 10 and 11, A data management program is the data set automatically DASD 1 4 to DASD 1 It moves to 5, It is only a data set frequently accessed by the host processor as a result DASD 1 By maintaining in four, it is host processor 101. The efficiency of access of the data set by 11 increases. DASD14 and 15 express the first two levels of data storage hierarchy created by the storage-of-data control program. A low level is mass storage system (MSS) 16 rather than being able to set to data storage hierarchy. L2 MSS1 and magnetic tape handler 17 L2 It is expressed with TAPE. MS816, DASD12, 14, and 15 enable automatic access of all the data sets memorized there. MS81B includes the automatic means for transmitting such a medium between one or more means for reading to a recording medium, and writing, and the storage cell, and reading and the writing means in MSS16. A magnetic disk or an optical disc may be [ recording medium ] sufficient also as magnetic tape, and a magnetic tape handler, or a magnetic disk drive or an optical disk unit may be sufficient as reading and a writing means. M8818 includes insertion or the means for removing for a recording medium in it again. Magnetic tape handler 17 is used for preservation or other prolonged storage of data, backup, etc., and usually needs an operator's intervention for attachment and removal of tape volume. A system operator and a system console are not shown in Drawing 3 in order to simplify a figure. In a desirable example, the storage-and-file-management program containing the present invention is a data function in a hierarchy memory manager (HSM), i.e., multiple virtual storage (MV S) operating system environment. General explanation of HSM is a U.S. Pat. No. 4771375 specification and a 4638424 specification, IBM manual SH35-0085-3 r data functional hierarchy memory manager, Guidance of version 2 and release 4.01 system programmer (DATA FACILITY!{IERARCHrCAL STORAGE MANAGER VERSION 2RELEASE 4.0, System) Programmer's GuideJ sIBM manual SH35-0083-3 r data functional hierarchy memory manager, Barge hand A 2, the command explanatory of release 4.01 system programmer (DATA FACILITY HIERARC}IIcAL STORAGEMANAGER VERSION 2 RELEASE 4.0, SystemProgrammer's) Coyuiand Reference J N, an IBM manual LY35-0098-1 r data functional hierarchy memory manager, barge a A 2, release 4.0, It has appeared in guidance (DATA FACILITY IIIERARcIIIcALSTORAGE HA} IAGER VERSION 2 RELEASE 4.0.Diagnosis Guide) of diagnosis. These indications are united on these specifications by quotation. HSM is an application operating program which runs continuously. A command which resides in host processor 101 11 permanently is included. HSM transports a data set between the levels from which data storage hierarchy differs according to predetermined specification, Data processing system space management is performed, and availability management is performed predetermined or by backing up a data set according to the specification led by a user, and Dumb(ing) data volume. The present invention can raise the efficiency of the recording medium of any forms used within a data processing system. The method according to the present invention is explained in Drawing 3 about a desirable example when data is recorded on magnetic tape handler 17. Speaking concretely, magnetic tape handler 17 being an IBM3480 magnetic tape handler, and a recording medium's being a magnetic tape cartridge which memorizes a maximum of 200 M bytes of data volume. A magnetic tape handler control mechanism compresses data, and maintains a counter including the predetermined information about the data written in there after equipping with a tape cartridge at the end so that it may mention below. As mentioned above, the data which should be recorded is compressed in the magnetic tape handler control mechanism committed as a buffer to a tape cartridge. Data compressions are U.S. Pat. No. 4463342, 4467317, and U.S. patent application. An item, IBM Technicanoire disclosure BenoitenV o l %27, No.8 (November, 1984), I! It carries out according to .3275~3278. These indications are united on these specifications by quotation. The data transmitted to a control mechanism in order to record is called logic data or incompressible data. The data already compressed by the magnetic tape handler control mechanism is called compressed data. The data recorded on the tape cartridge is called physical data. Therefore, the difference between logic data and physical data is a number of bytes (namely, quantity) of the continuous memory space on a tape cartridge required to memorize data. The logic data which it tries to write in on a tape cartridge is transmitted to a magnetic tape handler control mechanism from a host processor, when the minimum block of 16-K byte data is an incompressible form. This data is compressed by the magnetic tape handler control mechanism, and is stored with a compressed type. If the data of the big amount of thresholds is stored in a control mechanism and a buffer, data will be physically recorded on a tape cartridge. The data set currently written in arbitrary given time is called the present data set. The counter of a magnetic tape handler control mechanism maintains the statistics of a certain kind used in order to supervise the quantity (namely, position of a tape) of the recorded tape in a tape cartridge. One counter counts the quantity of the logic data which the magnetic tape handler control mechanism actually received, and another counter counts the quantity of the physical data written in into the tape cartridge, and also another counter counts the number of the gaps between blocks in physical data. As mentioned above, a counter is reset whenever it equips with a tape cartridge. Access to the information in a counter is READ. It carries out by issuing the BUFFEREDLOG command. The structure of a counter and operation are common knowledge at a person skilled in the art. As mentioned above, common DASD12 memorizes some control data structures. DASD 1 2 contains the transfer control data set (MCDS) for transfer volumes, and the backup control data set (BCDS) for backup volumes. A control data set is accessed by specifying a record tape and a record key (VOLSER). This structure and operation are common knowledge at a person skilled in the art. A control data set maintains the fixed information about each tape cartridge including the tape position in the output termination after equipping a magnetic tape handler with a tape last time. That is, this position shows the whole quantity of the physical data on the tape cartridge in the termination of wearing last time including the actual length of data and the gap between records. The number of bytes of all the logic data required to write in a tape cartridge between the present wearing is also contained in a control data set. This number does not contain the gap between records. Finally, a control data - set contains the number of bytes of all the physical data on a tape cartridge. The gap between records does not contain this, either. HSM maintains statistical information of a certain kind to the main memory unit of an activity host processor. This information includes the quantity of the logic data sent to the magnetic tape handler control mechanism, and a related number of a block of counts. Other required information is maintained by the main memory unit so that it may mention below. In Drawing 1, the method of the present invention is started from Step 30, when a magnetic tape handler is equipped with a tape cartridge. At Step 31, in order that a host processor may supervise record logically, it is begun to transmit data to a tape cartridge. If record starts at Step 31, the quantity of the incompressible data sent to the control mechanism of a peripheral storage will be pursued by a main memory unit. Record is continued unless it reaches into Step 31 at the data of the amount of targets. In order to raise a possibility that a target is shown by Step 32 and a cartridge can be copied to other single cartridges, it can be set to the minimum capacity of a tape cartridge, and a storage-and-file-management person can also set to a desirable predetermined level. Record continues until it reaches at Step 33 in the end of a data set, unless a target is reached. If it reaches in the end of a data set, a flow of operation will go to Step 50 of Drawing 2 from branching step 33. If it reaches in the end of a data set, it will progress to Step 51 and the actual position on a tape or the quantity of the physical data on it will be calculated there. An actual position is calculated by extracting a count from a control mechanism so that a record host processor can be used. Quantity of the tape memory space used during the present wearing, The quantity (the last two quantity is usually equal) of the logic data actually recorded on the tape cartridge is deducted and calculated from the sum total of the quantity of the logic data sent to the number and magnetic tape handler control mechanism of the gap between blocks in the quantity of the written-in physical data, and physical data. Subsequently, the quantity of the memory space used is applied to the pre-count of the tape position from the last tape cartridge wearing. Next, a tape position is common DASD 1. It memorizes in the control data set to the specific tape cartridge in two. In order to remove a tape cartridge from magnetic Tab device E 7 and also to add data to data volume, when it is the back and re-inserts, A data cartridge can continue this method from the place of the last written in last time using the count memorized by the controlled data set. At Step 52, the number of presumption of the incompressible data byte in the following user data set which it tries to write in a tape cartridge is applied to the actual position calculated at Step 51. This sum total is an estimate of the tape position after record of the following user data set which it tries to write in. It is judged whether at Step 53, the sum total for which it asked at Step 52 may be inspected, and the following data set may start the problem of spanning. The two characteristics of the information received at Step 52 are inspected. First, the presumed incompressible byte size of the following data set which it tries to write in is inspected, and it judges whether it is larger than the size (a desirable example 8 M bytes) set up by the user or small. When the presumed incompressible byte size of the following data set which it tries to write in is bigger than 8 M bytes, it returns to Step 30 of Drawing 1. This result is because the big amount of space may be consumed in the end of the present tape cartridge, when using it in order to carry out volume finally compulsorily and to record a big data set on the following tape cartridge. The presumed incompressible byte size of the following data set which it tries to write in is the same as 8 M bytes, or when smaller than it, the logic estimate of the position calculated at Step 52 is compared with a predetermined desired value. this target may be the same as the target used at Step 32, or may not be the same. When the size of the following data set which it tries to write in does not exceed a target at Step 53, record returns to Step 30 of Drawing l. Therefore, when the estimate of the data set size by an incompressible byte exceeds 8 M bytes, Or when the estimated position of a tape does not exceed target capacity and this data set should be written in a tape, the writing of the data set to the present tape cartridge continues at Step 30 of Drawing 1. However, presumed output size is the same as 8 M bytes, or it is when smaller than it, And when the present estimated position of a tape cartridge when a data set is written in exceeds target capacity, After volume finally becomes compulsorily at Step 54 (FEOV), and a tape cartridge is removed and being equipped with a new tape cartridge, the following data set is continued. Subsequently, it returns to Step 30 of Drawing 1, and the record on a new tape cartridge is continued in this way. Although it did not reach at Step 33 in the end of a data set or being reached at Step 33 in the end of a data set, it returns to Step 31, and it appears until a target is filled with Step 32, and it is assumed that the writing to a tape cartridge continues. If a target is reached at Step 32, it will progress to Step 35 and will calculate the quantity and the statistics value of a certain kind of the actual position of a tape cartridge, or the physical data of a tape cartridge. Calculation of the actual position of a tape is the same as the calculation already described at Step 51. Step 35 includes the statistics calculation which is needed in order to further supervise the record on the present tape cartridge. Calculation of the compression ratio about the present data set is included in these statistics. A compression ratio is the value which expressed the ratio of the amount of compressed data bytes recorded to a certain data cent to the amount of incompressible data bytes to the recorded data with percent. Speaking more concretely, this ratio's being the quotient divided by the number of blocks with a physical data byte and a logic data byte by whom the number of gaps between blocks was sent to a magnetic tape handler control mechanism. All of these numbers are accessible in a main memory unit or a magnetic tape handler control mechanism. Using the compression ratio about a data set, the number of bytes required to remember the remaining unrecorded logic bytes in the present data set on a data cartridge is predicted. At Step 36, record is continued and it supervises physically. Physical surveillance means presuming the number of physical data bytes required for a record host processor to record the incompressible byte currently seen off in the control mechanism using a compression ratio. At Step 37, the estimated position of record in a compressed data byte is compared with a desired value, continuing record. also in this case, the desired value of Step 37 may be the same as the target used at Step 32 or front step 53, or may differ. Unless a target is filled, record continues at Step 38 and it detects the end of the recorded data set like Step 33. Unless the end of the recorded data set is detected, record continues at Steps 36 and 37. However, if the end of a data set is detected, it will move to Step 50 of Drawing 2 also in this case. From Step 50, it continues as mentioned above. If it assumes that the end of a data set is not detected at Step 38, physical surveillance will continue at Steps 36 and 37. If it is shown that the probability that it becomes impossible to copy a tape cartridge to other single tape cartridges if a target is reached at Step 37 and also it records is large, volume will be compulsorily completed at Step 40, and it will return to Step 30, and will insert a new tape cartridge. Even if volume is compulsorily completed at Step 40, tape spanning is not necessarily compensated but a target may be filled in the middle of a data set. When carrying out operation of Drawings 1 and 2, the control mechanism information taken out from a magnetic tape handler control mechanism needs to be exact. However, an operating system is able to sometimes unload such information for error record report software. If an operating system is made to Afroad information in order to record an error, a counter will usually be reset. Since the storage-and-file-management program cannot access an error record program, it needs to include detection of when the information in a magnetic tape handler control mechanism becomes inaccurate to this method. Although this inspection is not shown in all the figure for convenience, either, when access to such information is required, it carries out always. Detection of things with inaccurate information is carried out by maintaining the number of incompressible data bytes written in a tape cartridge during continuation wearing of a tape in a main memory unit. This number must be equal to the count number maintained in a magnetic tape handler control mechanism. By comparing two counters, it is possible to judge whether reset occurred in the magnetic tape handler control mechanism. This loss must be compensated when loss of magnetic tape handler control mechanism information is detected once. Two adjustment methods are possible. In the 1st method, if the difference of a counter is detected, it will be assumed that all the data recorded on the recording medium is incompressible data in practice. That is, the number of incompressible bytes recorded on the recording medium is set up similarly to the number of incompressible bytes detected by the host processor, when record is performed. Other methods are desirable examples, and although this includes the same kind of assumption, it is only about the byte lost from the counter. That is, when a byte count with a specific main memory unit is shown and a magnetic tape handler control mechanism is reset during the count, a magnetic tape handler control mechanism will show the subset of a smaller number or a main memory unit count. As far as the physical data or compressed data which exists in a magnetic tape handler control mechanism is then related with the count shown with an incompressible form in a buffer, it will be assumed that it is exact. The difference of the incompressible data byte count in the remaining bytes, i.e., a main memory unit, and a magnetic tape handler control mechanism can be compensated by assuming that compression was not performed. Thus, loss of the data in a magnetic tape handler control mechanism can be compensated. This method can be used also with various kinds of recording media other than magnetic tape, such as a magnetic disk and an optical disc. F. EFFECT OF THE INVENTION According to the present invention, a removal type data recording medium can be used efficiently, the quantity of the compressed data memorized without increasing a host processor overhead in particular can be supervised correctly, and a possibility that a recording medium can be copied is improved. The record over two or more recording media, i.e., spanning, can be decreased.

[Brief Description of the Drawings]

Drawing 1 is a flow chart showing the present invention. Drawing 2 is a flow chart linked to the flow chart of Drawing 1. Drawing 3 is a schematic diagram of the multi-host data processing system which has a plurality of peripheral data storage equipment manageable according to the present invention. 101 11 .... host processor, 12 .... common DASD, 14 .... high performance (LO) DASD 15 .... low performance (Ll) DASD 16 .... mass (L2) memory system (MSS), 17 .... magnetic (L2) tape device. The 4th A flash Drawing 2