METHOD AND ARRANGEMENT FOR STORING INFORMATION PRODUCED BY A SWITCHING EXCHANGE SYSTEM ON TAPE

Abstract: The invention relates to a method and arrangement for storing information produced by a switching exchange system on tape. In accordance with the invention, storage is effected in the following phases: reading data into an intermediate file (IF) for increasing the number of records to be stored to an amount suitable for the capacity of the recorder (T) used; copying the intermediate file (IF) into a backup storage (M); emptying the intermediate file (IF) to a tape for a new read cycle of information produced by the switching exchange system.

Description: Method and arrangement for storing information produced by a switching exchange system on tape The invention relates to a method and arrange- ment for storing information produced by a switching exchange system on tape. The requirements for storing data in exchange systems vary widely. Charging data and different traffic measurement reports are stored by mag¬ netic tape recorders. In addition, backup copies of disk files are usually stored on magnetic tape. It is worth storing data on magnetic tape if larger amounts are to be stored into a portable permanent storage. Charging data is produced as a switching ex¬ change switches calls. Charging data is stored on mag- netic tape almost in real time and thus the amount of data to be stored at a time may be small. In addition, data storage is periodic and non-predefined, as the fre¬ quency for storing data depends on the number of calls. The requirements set by switching exchange sys- terns on storage of charging information are continuously increasing. The required traffic volumes grow. In addi¬ tion, the trend is increasingly toward call-by-call charging, whereat records to be stored on tape are pro¬ duced from each call. The amount of data to be stored is so large that the capacities of conventional start/- stop-type recorders currently used in storing charging information are insufficient with high traffic. On the other hand, streamer-type recorders are too slow with low traffic. Magnetic recorders are classified in two cat¬ egories based on the storage type: start/stop-type recorders and streamer-type recorders. Start/stop recorders start tape movement always when the recorder receives a data block to be stored and stop the tape after storing the data block. Streamer-type recorders do not stop the tape between data blocks if a new block reaches the recorder soon enough. Start/stop recorders are faster than streamer recorders when data is stored in relatively small amounts at a time, as in start/stop recorders stopping and starting the tape is mechanically realized signific¬ antly faster than in streamer recorders. If data can be stored on tape as a continuous data stream so that the recorder does not have to stop the tape before a new data block to be stored reaches the recorder, a streamer recorder is faster. In this case storage rate is about equal to that of hard disks. In addition, the storage capacity of streamer recorders is usually considerably higher, around several gigabytes, than that of start/- stop recorders, which is below 100 megabytes. If a streamer recorder is used for storing small amounts of data so that the recorder stops the tape before the next data to be stored reaches the recorder, one storage may, depending on the recorder, require even 15 seconds, if the length of the data to be stored is less than 1 kB. The total storage capacity of streamer re¬ corders decreases the more frequently the tape has to be stopped during storage. During stop and start the tape moves considerably before the speed of the tape is adequate for storage or until the tape has stopped. This part of the tape cannot be used for storage of useful data. The mechanics of start/stop recorders prevent a corresponding long interval, where no useful data can be stored, from being created on the tape. An object of this invention is to provide a method and an arrangement by means of which a high-capa¬ city streamer-type recorder may be used in all storage situations. The method of the invention is characterized in that storage is effected in the following phases: - reading data into an intermediate file for increasing the number of records to be stored to an amount suitable for the capacity of the recorder used; - copying the intermediate file into a backup storage; - emptying the intermediate file to a tape for a new read cycle of information produced by the switching exchange system. In accordance with the invention, the software controlling the recorder sees to it that data is written to the recorder in an adequately sized whole for keeping the recorder in the streamer mode during the entire stor¬ age. For the software producing the data, i.e. requiring storage, this is a completely invisible operation. Generally an application software producing data requires confirmation of the data having been stored into a permanent storage. Thus the application software must not be notified of a successful data stor¬ age before confirmation of successful data storage has been received from the permanent storage. The solution of the invention is in no way re¬ lated to known virtual and cache memories in which data selected by certain criteria is kept, in a disk or main storage, accessible to the central processing unit of a computer. In the invention the data passing via an intermediate memory is unidirectional (on its way to a mass storage for final storage) and irrelevant as to the function of the central processing unit, and the storage may thus be preferably effected as a background run. The preferable embodiments of the method and arrangement of the invention are characterized in what is set forth in the attached claims. In the following the invention will be de¬ scribed in more detail by way of an example with refer- ence to the accompanying drawing, which is a block diagram of an arrangement according to the invention. When a software OP controlling a recorder has received data to be stored from a central processing unit CU of a switching exchange system, it stores the data in an intermediate file IF, situated in RAM (Random Access Memory). A copy of the intermediate file is main¬ tained in a fast permanent storage memory M, which may be a hard disk, a battery-backup RAM disk or any fast medium, where data remains stored even after a power failure. After the data is stored into a file and the file is stored into a permanent storage, a message of successful storage is sent to the software which sent the data. At this point the data is thus necessarily not yet on the tape. Data storage from the intermediate file IF to a tape may be started when enough data is stored in the intermediate file. This is automatically effected as a background run. The software OP controlling the recorder T identifies the type of recorder used and defines the storage limits accordingly. If the apparatus to be con¬ trolled is a start/stop recorder, intermediate storage is not required. Thus the intermediate file of the in¬ vention is preferably used only when necessary. Even when a streamer recorder is used as a backup unit for disk files, the intermediate file is not needed as the backup copying is adequately fast as such for keeping the recorder in streamer mode. When the recorder T is again used for storing charging data, the intermediate file IF is taken into use. The purpose of use of the recorder T (backup, storage of charging, etc. ) is stored into a file con¬ trolled by the control software OP of the recorder. An operator may set the desired purpose of use of the re- corder. The operator may also by a command empty the intermediate storage to a tape e.g. in connection with change of tape. The intermediate file IF is only in the immedi¬ ate use of the software (OP) controlling the recorder. Protection offered by the operating system is used for file protection. If the exchange system computer unit is doubled, the intermediate file IF in the RAM must be copied also to the backup unit. The copy of the inter¬ mediate file IF in the fast permanent storage M must be protected from other users of file services. Taking a backup copy of the file IF must, however, be possible. The intermediate file also contains information stating if data storage to the intermediate file IF is in pro¬ cess and also if emptying of the intermediate file to a tape is in process. When the file is being emptied to a tape, other storage tasks directed to the tape in question are not dealt with until the intermediate file has been emptied. When a computer unit CU is started, the control software OP checks if data has been stored into the in¬ termediate file IF. If the file contains data and the emptying of the file to the tape is uncompleted, i.e. if the central processing unit CU is reset when the in¬ termediate file IF is being emptied to the tape, the emptying must be continued from the right point. By com¬ paring the data at the end of the tape with the data in the intermediate file, the starting point can be found and the emptying of the intermediate file may be con¬ tinued from the right point. If the break point is not found by comparing the data, the interpretation is that the resetting has occurred after the storage was started, but before the data was copied to the tape. Consequently the whole of the data in the intermediate file IF may be written to the tape after the existing data. Emptying the inter- mediate file is in any case started after restart of the central processing unit CU if the intermediate file contains data that has not been stored. Each time the control software OP of the re- corder T receives data to be stored, it first tries to store the intermediate file IF into a permanent storage. If this fails, the data is immediately stored on tape, and thus the intermediate file is not used until storage into the permanent storage again succeeds. The control software of the recorder will set an alarm if storage of the intermediate file IF into the permanent storage M or on tape fails. If storing the intermediate file into the permanent storage fails, the intermediate file is emptied to a tape. The application software receives confirmation only after the data is stored on tape. An error message is sent to the application software if storage on tape fails and the intermediate file IF is not used. At this point the application may, if desired, retry to store the data. Confirmation to the application software is not sent until the data is stored (or has been attempted to be stored) into a per¬ manent storage. In case of an error during storage on tape when the intermediate file is being used, the application software receives no error confirmation thereof. The data is, however, stored in the permanent storage M, i.e. the data is not lost and the application has no need to restore the data. The data is stored in the intermediate file if the tape drive is damaged or the tape is full. When the recorder is again in working order, the intermediate file is automatically emptied to the tape on the same principle as when the computer unit is started. It is evident to a person skilled in the art that the different embodiments of the invention are not limited to the above example, but may vary freely within the scope of the attached claims.

Claims: Claims 1. A method for storing information produced by a switching exchange system (CU) on tape, c h a r - a c t e r i z e d in that storage is effected in the following phases: - reading data into an intermediate file (IF) for increasing the number of records to be stored to an amount suitable for the capacity of a recorder (T) used; - copying the intermediate file (IF) into a backup storage ( ); - emptying the intermediate file (IF) to a tape for a new read cycle of information produced by the switching exchange system. 2. A method as claimed in claim 1, c h a r ¬ a c t e r i z e d in that confirmation of successful storage is given immediately after the intermediate file (IF) is stored into the backup storage (M). 3. A method as claimed in claim 1 or 2, c h a r a c t e r i z e d in that a disk storage or the like, protected from power failure, is used as the back¬ up storage (M). 4. A method as claimed in claim 1, 2 or 3, c h a r a c t e r i z e d in that when copying the intermediate file (IF) into the backup storage (M) fails, the intermediate file is emptied to a tape, whereat confirmation of successful storage is not given until the information is stored on tape. 5. A method as claimed in any of claims 1 through 4, c h a r a c t e r i z e d in that storage into the intermediate file (IF) is effected only when the recorder (T) used is of streamer-type. 6. A method as claimed in claim 5, c h a r ¬ a c t e r i z e d in that storage into the intermediate file (IF) is effected only in cases when charging data produced by a switching exchange system (CU) is stored to a streamer-type recorder (T). 7. An arrangement for storing information produced by a switching exchange system on tape, c h a r a c t e r i z e d in that the arrangement comprises software (OP) for controlling the storage and the functions of a recorder, an intermediate file (IF) for reading data in order to increase the number of records to be stored to an amount suitable for the capacity of the recorder used, a backup storage for storing a copy of the intermediate file, and a tape unit for receiving the data contained by the intermediate file. 8. An arrangement as claimed in claim 7, c h a r a c t e r i z e d in that the backup storage is a disk storage or the like protected from power failure. 9. An arrangement as claimed in claim 7 or 8, c h a r a c t e r i z e d in that the recorder is a streamer-type recorder.

Inventors: PEHKONEN TAPIO, PEHKONEN, TAPIO
Applicants: NOKIA TELECOMMUNICATIONS OY, PEHKONEN TAPIO, PEHKONEN, TAPIO
Application year: 1995
Main classification: G06F13
IPC codes: G06F3, H04M3, H04M15