International Business Machines Corporation

Yumiko Ohta

Yutaka Oishi

Masayuki Iwanaga

Atsushi Abe

Terue Watanabe

Setsuko Masuda

A computer-implemented metadata processing method and a system includes writing metadata to or reading metadata from a storage medium in which an index that contains metadata of each of one or more pieces of data is stored. The method and system include determining, in response to a processing request, which includes a write request or a read request, when to communicate with a storage area outside the index. At least a portion of content of the metadata relating to the processing request is processed, and accessed, including storing or obtaining, in the index, location information indicating the storage area of the portion of content of the metadata.

Metadata storing technique

A method for writing a file from an application of a host onto a tape includes sequentially receiving records forming the file from the application, adding a predetermined number of segments of dummy data (dummy records) subsequently to the plurality of records forming the file such that the records of the file and records of a subsequent file are not included in the same data set, interposing the dummy records between a final record of the file and a head record of the subsequent (next) file, to thereby construct at least one data set that is adjacent to one data set and does not include the records of the file, and writing a data set including the records of the file, a data set (dummy data set) including the final record of the file and the dummy records, and a data set including the subsequent file, onto the tape.

Deleting files written on tape

In one embodiment, a magnetic tape device includes a read control configured to sequentially read records included in data sets from a tape medium into a buffer, and send the records included in the data sets to a host in response to determining that there is no C2 error during reading of the data sets. The read control is also configured to skip a predetermined error recovery process in accordance with a video special mode in response to detecting a C2 error during reading of the data sets.

Transferring multiple records including video data to/from host

An icon corresponds to a history of files related to a plurality of indexes. Each of the indexes and each of the files are additionally and synchronously recorded in storage as additional data. The icon displayed represents the status of data in the files in the storage. The displayed icon is manipulated to indicate whether no data exists in an associated file or to indicate that existing data in an associated file was updated.

Icon display of file history recorded in storage as additional data

Mechanisms for splitting and spanning a single file across a plurality of tape media in a tape drive file system are provided. The mechanisms format the tape media so as to store an index of the file and data on the file in the tape media in a predetermined format; splitting the single file into separate portions and managing at least one of IDs identifying the plurality of tape media that sequentially store the portions of the file in association with the file; and storing a generation number indicating the number of storing and updating each of the file portions as the index in each of the tape media. Upon receiving a request to read the stored split file, the system obtains an index on a tape medium storing a file portion whose generation number is the highest and reads a time stamp related to the size and update of the single file.

Method, storage system, and program for spanning single file across plurality of tape media

Techniques for reducing the time required for erasing specific data recorded on a tape medium. A specific group of records is erased without preliminarily locating the erasure end position. This is carried out by simultaneously utilizing three heads, that is, two read heads and one write head, to detect the erasure end position during data erasure. Various embodiments are applicable to tape media as well as other storage media. Various embodiments are not only applicable as a file system cooperating as a combination of hardware (H/W) and software (S/W), but also applicable in systems, such as databases, that directly use storage without an intermediary file system.

Erasing recorded data by utilizing read head and write head

Provided are a storage device, controller, and method for using host transfer rates to select a recording medium transfer rate for transferring data to a recording medium. A host transfer rate of data with respect to a buffer is measured. Provided are a plurality of recording medium transfer rates at which data is transferred between the buffer and the recording medium. A determination is made of an amount of decrease in the host transfer rate. The recording medium transfer rate is selected based on the amount of decrease in the host transfer rate. A transfer rate at which the storage device transfers data is set to the selected recording medium transfer rate.

Using host transfer rates to select a recording medium transfer rate for transferring data to a recording medium

Mechanisms are provided for performing a synchronization operation for synchronizing data to a tape medium. The mechanisms receive a request to perform the synchronization operation on the tape medium and obtain file information from a storage device in response to the request. The mechanisms determine if the file information is associated with a file that has been changed since a last index was written to the tape medium. In response to the file information being determined to be associated with a file that has been changed since a last index was written to the tape medium, the mechanisms add index information corresponding to the file information to a partial index. The partial index comprises index information for files less than a total number of files recorded on the tape medium. The mechanisms write the partial index to the tape medium.

Index writing in a linear tape file system

In one embodiment, a method includes receiving from the host a video special mode for reading video data, and sequentially reading the records included in data sets from the tape medium into segments of a buffer. When there is a C2 error during reading of the data sets, a predetermined error recovery process is skipped in accordance with the video special mode. When management information (DSIT) for the data set having the C2 error is available for reading, sending of the record(s) included in the data set having the C2 error to the host is skipped. For the data set having the C2 error, the number of records to be skipped included in the data set having the C2 error based on and from the DSIT is obtained and indicated to the host.

Transferring multiple records including video data

A method is provided for automatically reclaiming areas with unneeded data in a tape cartridge (medium) storing files updated by appended writing. In this reclamation method, the appended writing entails the sequential compression of data needed by the updated file (needed data) and data not needed by the file (unneeded data) and storage of the compressed data on the medium, and the medium is divided into at least three data partitions for the storage of data.

Reclamation of data on tape cartridge

A tape medium uses a format to store data in which the tape medium is partitioned into an index partition (IP) and a data partition (DP). The latest metadata related to additional data newly added and written to the DP in accordance with the format is updated and stored in the IP. The same metadata is repeatedly written after the updated metadata (e.g. Index #1) in the IP. Alternatively, additional data newly added and written to the DP is stored in memory, and is called from memory and then added and written after metadata (e.g. Index #0) during the formatting. In either manner, data written prior to formatting may be recovered.

Recovery of data written before initialization of format in tape media

Mechanisms for writing a file on a tape medium in a manner that enables high-speed reading are provided. A predetermined format is applied to the medium that divides the medium into a first region of a predetermined length in a longitudinal direction from a region of the medium, and a second region that extends from an end of the first region to a terminal region of the medium in a longitudinal direction and that has a predetermined width with respect to a width of the medium in a transverse direction. Writing a top data portion of a predetermined data amount of the data of the file in the first region and writing data of the file in the second region are performed.

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Yokohama, Japan

Yumiko Ohta