International Business Machines Corporation

Steven Bennett Wilson

Scott Milton Fry

Steven Douglas Johnson

Robert Beverley Basham

Carl Evan Jones

Kirby Grant Dahman

Glenn Rowan Wightwick

John James Gniewek

Edwin C Dunn

Orvid B Jeppson

A method for processing a point-in-time copy of data associated with a logical storage volume where the data to be copied is stored in a striped or parallelized fashion across more than one physical source volume. The method includes receiving a point-in-time copy command concerning a logical volume and distributing the point-in-time copy command in-band to each of the physical source volumes containing a portion of the striped data. The method also includes establishing a point-in-time copy relationship between each physical source volume and one of a corresponding set of multiple physical target volumes. The method further includes copying the data stored on each physical source volume to the corresponding physical target volume. The in-band copy command and the striped data may be distributed over I/O channels between a server and the physical storage and processed sequentially.

Achieving data consistency with point-in-time copy operations in a parallel I/O environment

Optimizing the retrieval of blocks of data from a tape media of a longitudinal serpentine tape drive. A device block map (DBM) is retrieved from the tape media and stored in memory. The DBM comprises a table having one or more rows and one or more columns for each block of data stored on the tape media. The columns are selected from the group comprising a wrap column, a position column, a logical block column, and a file identifier column. One or more retrieval paths for requested blocks of data are determined from an image of the physical layout of the requested blocks on the tape media generated by linear interpolation of the DBM stored in memory. Each of the retrieval paths comprises an ordered sequence of the blocks of data and the manner in which the tape media is to be traversed to accomplish the retrieval of the ordered sequence. A sum of distances is determined for each of the retrieval paths and an optimal one of the retrieval paths is selected based on the determined sum of distances. Thereafter, the blocks of data are retrieved from tape media using the optimal retrieval path.

Host-available device block map for optimized file retrieval from serpentine tape drives

A data storage system for use with a tape cartridge storing data in a serpentine pattern on tape media, and having a memory device for storing a device block map for the tape median, comprises tape drive, or a loading mechanism, which first positions the tape cartridge at memory interface for transfering the device block map from the memory device to a processor, and subsequently positions the tape media for reading and/or writing. The processor processes the device block map from the memory device for optimal retrieval of the serpentine pattern data of the tape media. The processing of the device block map occurs while the tape media is positioned for reading and/or writing, so that the processor begins the retrieval reading process immediately upon the positioning of the tape media. In another aspect of the invention, a robotic accessor of an automated data storage library moves the tape cartridge to the tape drive. The tape cartridge is positioned at the memory interface on the robotic accessor, and the stored device block map is transferred from the memory device to the processor, during the move.

Retrieval of serpentine pattern data using a memory device of a tape cartridge

Various data storage formats help to efficiently locate, read, and write user data stored on magnetic tape media. A tape is formatted by writing multiple segment-headers, free from any interleaved access of user data Adjacent segment-headers are spaced by a predetermined interval to define multiple data storage segments. Segment-headers all contain a unique key, which is copied into a key index to identify valid segments. After formatting, normal tape accesses can be performed. Without erasing any old headers or data, a new formatting scheme can be established by writing new segment-headers on the tape. The new segment-headers include a new unique key, replacing the previous key in the key index. Previous segment-headers stored on the tape are ignored, since they lack the updated key. Segments may be selectively grouped to provide independently addressable partitions. Mapping between segments and partitions can use a fixed relationship (e.g. one-to-one), or each partition may be variably sized according to the amount of data to be stored therein. Variable-sized partitions may be automatically padded with a selected number of empty segments. Another feature is flexible-capacity scaling, which distributes an ordered set of device blocks on a multi-track magnetic tape medium. The device blocks are bi-directionally stored in a continuous configuration of multiple adjacent stacked serpentine patterns occupying some or all of the tape. This configuration permits sequential access of all device blocks without advancing the tape medium to skip over regions between adjacent device blocks.

Tape pre-formatting with uniform data storage segments selectively

Various data storage formats help to efficiently locate, read, and write user data stored on magnetic tape media. A tape is formatted by writing multiple segment-headers, free from any interleaved access of user data. Adjacent segment-headers are spaced by a predetermined interval to define multiple data storage segments. Segment-headers all contain a unique key, which is copied into a key index to identify valid segments. After formatting, normal tape accesses can be performed. Without erasing any old headers or data, a new formatting scheme can be established by writing new segment-headers on the tape. The new segment-headers include a new unique key, replacing the previous key in the key index. Previous segment-headers stored on the tape are ignored, since they lack the updated key. Segments may be selectively grouped to provide independently addressable partitions. Mapping between segments and partitions can use a fixed relationship (e.g. one-to-one), or each partition may be variably sized according to the amount of data to be stored therein. Variable-sized partitions may be automatically padded with a selected number of empty segments. Another feature is flexible-capacity scaling, which distributes an ordered set of device blocks on a multi-track magnetic tape medium. The device blocks are bi-directionally stored in a continuous configuration of multiple adjacent stacked serpentine patterns occupying some or all of the tape. This configuration permits sequential access of all device blocks without advancing the tape medium to skip over regions between adjacent device blocks.

Flexible-capacity scaling for efficient access of ordered data stored on

A storage media for linear, serpentine recording is pre-formatted for data storage operations by recording partition format information in a single pass along the length of the storage media by recording partition format information for all storage media tracks at regular partition intervals defined by index locations alternately in both storage media directions before moving the storage media to the next partition interval. At each index location, partition markers are recorded in successive parallel tracks first in one media direction and then the other until markers are recorded across the entire width of the storage media. The steps of moving to a next partition index location, recording partition information in successive parallel tracks in first one direction and then the other, and moving to a next index location one partition length away, are repeated until all partitions of the storage media are pre-formatted.

Pre-formatting of a storage media having fixed-size partitions

The invention is one or more tape systems which determine the length of tapes mounted therein to assess the thickness of such tapes. A format identifier is written at one of a plurality of locations on the tape depending upon the tape thickness. The format identifier for a relatively thin tape is written further from the leader block than that for a relatively thick tape, thereby avoiding the writing of user data in a region of the tape embossed with wrap deformations. The thickness determination is combined with a determination of the tape format to assess the compatibility of a desired operation on a tape mounted in a tape system therewith. If the operation is not compatible with the tape and the tape system, the tape system will not permit such operation to continue. A method for operating the tape systems is also disclosed, and accounts for various contingencies, such as blank tapes and marginal determinations of tape thickness.

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Tucson, AZ, United States of America

Steven Bennett Wilson