International Business Machines Corporation

Netapp, Inc.

Danit Segev

Yoram Novick

Yigal Eisinger

Gabriel G Walder

James T Brady

Olympia Gluck

Norman Ken Ouchi

Erez Webman

Oded Cohn

Joe-Ming Cheng

James W Eldridge

A group stamping style asynchronous replication service utilizes a loosely-accurate global clock in a data backup and recovery storage environment. The storage environment includes a set of source storage systems illustratively embodied as source replication nodes that cooperate to maintain a consistency group that may span multiple geographical sites. The storage environment also includes one or more target storage systems illustratively embodied as target replication nodes configured to service the consistency group. The group stamping style service utilizes the loosely-accurate global clock to provide consistent replication of a storage space, e.g., a target storage space, of the consistency group.

Group stamping style asynchronous replication utilizing a loosely-accurate global clock

A method for data backup includes creating a sidefile in a cache memory of a data storage system. Entries are added to the sidefile specifying copy operations to be respectively performed by copy services in the system, including at least first and second copy services of different, first and second types. The copy operations specified by the operations are then executed using the first and second copy services.

Efficient data backup using a single side file

A method that uses a single callback function for a multiphase service with possible discontinuation of execution between the phases. The method is based on assignment of a case in the callback function for each phase or state of the service and a stack of state descriptors. At each call to the callback function, the top descriptor is popped off the stack and the appropriate case in the callback function is run.

Efficient thread programming using a single callback function

A method for operating a data storage system that is comprised of at least one disk. The method includes a step of partitioning a data compression unit into n basic compression units, where n is greater than one. Each data compression unit is comprised of a plurality of disk sectors and each of n basic compression units begins with a different initial sector. A next step partitions the data compression unit into X intervals, where X is less than n. Each of the X intervals begins with a different initial sector and within one of the n basic compression units. Further steps of the method include storing, external to the at least one disk, a plurality of first pointers each of which points to the initial sector of one of the n basic compression units wherein the 1/X, 2/X, . . . , (X-1)/X intervals begin; storing, within each of the initial sectors of the individual ones of the n basic compression units wherein the 1/X, 2/X, . . . , (X-1)/X intervals begin, a second pointer to the initial sector of the interval that begins within the basic compression unit; and, in response to a disk read operation that reads a compressed data unit that begins with one of the sectors that is located within one of the X intervals, accessing the beginning sector of the compressed data unit in accordance with one of the first pointers and one of the second pointers. The step of allocating includes a step of determining an actual compression ratio for the record, determining a value of a longest run of identical characters within the record, and adjusting the actual compression ratio based on the value of the longest run of identical characters. The step of allocating also includes a step of adding at least one additional sector to the estimated number to enable the compressed record to be subsequently updated in place.

System for storing pointers to initial sectors of variable length n

Growing community of inventors

Haifa, Israel

Danit Segev