Emc Corporation

Moshe Yanai

Natan Vishlitzky

Bruno Alterescu

Daniel Castel

Gadi G Shklarsky

Yuval Ofek

Daniel D C Castel

Douglas Eric LeCrone

Bruno Altersecu

Daniel D Castel

Yuval Y Ofek

Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy-remote write pending, and adaptive copy-disk. Direct write access to a secondary volume is denied if a 'sync required' attribute is set for the volume and the volume is not synchronized.

Remote data mirroring

A primary data storage system is linked to a geographically remote secondary data storage system for automatically maintaining a remote copy of the data in the primary storage. The primary data storage system has a primary cache memory, and the secondary data storage system has a secondary cache memory. The primary data storage system controller has a first remote link adapter coupled between the primary cache memory and the communications link for transferring the data to the communications link. The secondary data storage system controller has a second remote link adapter coupled between the communications link and the secondary cache memory for transferring the data from the communications link to the secondary cache memory. In this fashion, the first remote link adapter and the second remote link adapter automatically transfer the data to the secondary cache memory for writing of the data into the secondary data storage.

Remote data mirroring system having a remote link adapter

Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy&#x2014;remote write pending, and adaptive copy&#x2014;disk. Direct write access to a secondary volume is denied if a 'sync required' attribute is set for the volume and the volume is not synchronized.

A primary data storage system is linked to a geographically remote secondary data storage system for automatically maintaining a remote copy of the data in the primary storage. The primary data storage system controller uses write pending indicators to control and coordinate the remote copy process. In response to receipt of data from the host computer, a first write pending indicator is set to write the data into at least one primary data storage device, and a second write pending indicator is set to copy the data to the secondary data storage system controller. The first write pending indicator is reset after the data is written to the primary data storage device, and the second write pending indicator is reset after receiving an acknowledgement back from the secondary data storage system controller.

Remote data mirroring system using local and remote write pending indicators

A primary data storage system is linked to a geographically remote secondary data storage system for automatically maintaining a remote copy of the data in the primary storage. Each of the data storage systems has at least one data storage device, a cache memory, a data storage system controller, and a service processor for servicing the data storage system. The primary and secondary service processors are linked to permit remote system configuration and remote software programming of the secondary data storage system, and to exchange a report of all the non-valid, out of sync tracks. The service processors can also perform the task of scanning for remote write pending bits to invoke the remote copy task, and checking for invalid track bits to invoke a task for copying data from a known good storage device to the device with the invalid track bit set.

Remote data mirroring system having a service processor

A system and method for providing on-line, real-time, transparent data migration from an existing storage device to a replacement storage device. The existing and replacement storage devices are connected as a composite storage device that is coupled to a host, network or other data processing system. The replacement storage device includes a table which identifies data elements that have migrated to the replacement storage device. When a host system makes a data transfer request for one or more data elements, the replacement storage device determines whether the data elements have been migrated. If the data elements have migrated, the replacement storage device responds to the data transfer request independently of any interaction with the existing storage device. If the data elements have not migrated, the replacement storage device migrates the requested data elements and then responds to the data request and updates the data element map or table. When not busy servicing other requests, the replacement storage device operates in a background mode to migrate data elements so the data migration can occur concurrently with and transparently to system operations.

System and method for on-line, real time, data migration

A data storage system includes data storage and a record locator data structure in random access memory. The record locator data structure includes entries having different lengths. For locating variable-length data records in the data storage, for example, at least some but not all of the entries have a data-length portion indicating data length of a respective data record of the entry when the data length of the respective data record fails to match an expected data length. Each entry, for example, has a fixed length portion including an indication of whether or not the entry has a data-length portion, the fixed length portions are stored sequentially in a first region of address locations of the random access memory, and the data-length portions are stored sequentially in a second region of address locations of the random access memory.

System and method for disk mapping and data retrieval

Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy-remote write pending, and adaptive copy-disk. Direct write access to a secondary volume is denied if a &ldquo;sync required&rdquo; attribute is set for the volume and the volume is not synchronized. If a &ldquo;volume domino&rdquo; mode is enabled for a remotely mirrored volume pair, access to a volume of the pair is denied when the other volume is inaccessible. In a &ldquo;links domino&rdquo; mode, access to all remotely mirrored volumes is denied when remote mirroring-is disrupted by an all-links failure. The domino modes can be used to initiate application-based recovery, for example, recovering a secondary data file using a secondary log file. In an active migration mode, host processing of a primary volume is concurrent with migration to a secondary volume. In an overwrite cache mode, remote write-pending data in cache can be overwritten. Write data for an entire host channel command word chain is bundled in one link transmission.

Asynchronous remote data mirroring system

An apparatus and method for disk mapping and data retrieval includes a data storage medium on which has been stored a plurality of data records. Each record includes at least a record identification portion, for uniquely identifying each record from among the plurality of data records. The apparatus builds a record locator table in high speed semiconductor memory which comprises the unique record identifiers for the records on the storage medium as well as a record locator index generated by the apparatus, which indicates the address of the data record on the storage medium. Data retrieval is facilitated by first searching the record locator table in high speed semiconductor memory for a requested data record. Utilizing the record locator index associated with the requested data record, the system directly H: accesses the requested data record on the storage medium thereby minimizing storage medium search time. Also disclosed is an apparatus and method for converting CKD formatted data records to FBA formatted disk drives and for building and compressing the &ldquo;count&rdquo; portion of the CKD data formatted record into a record locator table.

A method and apparatus for interfacing two ESCON compatible devices over a communication channel that is not dedicated solely to ESCON communication, such as a public communication network or links, for example, a T1 or T3 line. The devices may include a master storage device and a mirroring storage device disposed at remote locations. In one embodiment, the devices communicate using the ESCON protocol.

Method and apparatus for interfacing two remotely disposed devices coupled via a transmission medium

An apparatus and method for disk mapping and data retrieval includes a data storage medium on which has been stored a plurality of data records. Each record includes at least a record identification portion, for uniquely identifying each record from among the plurality of data records. The apparatus builds a record locator table in high speed semiconductor memory which comprises the unique record identifiers for the records on the storage medium as well as a record locator index generated by the apparatus, which indicates the address of the data record on the storage medium. Data retrieval is facilitated by first searching the record locator table in high speed semiconductor memory for a requested data record. Utilizing the record locator index associated with the requested data record, the system directly accesses the requested data record on the storage medium thereby minimizing storage medium search time. Also disclosed is an apparatus and method for converting CKD formatted data records to FBA formatted disk drives and for building and compressing the &ldquo;count&rdquo; portion of the CKD data formatted record into a record locator table.

Two data storage systems are interconnected by a data link for remote mirroring of data. Each volume of data is configured as local, primary in a remotely mirrored volume pair, or secondary in a remotely mirrored volume pair. Normally, a host computer directly accesses either a local or a primary volume, and data written to a primary volume is automatically sent over the link to a corresponding secondary volume. Each remotely mirrored volume pair can operate in a selected synchronization mode including synchronous, semi-synchronous, adaptive copy-remote write pending, and adaptive copy-disk. Direct write access to a secondary volume is denied if a &ldquo;sync required&rdquo; attribute is set for the volume and the volume is not synchronized. If a &ldquo;volume domino&rdquo; mode is enabled for a remotely mirrored volume pair, access to a volume of the pair is denied when the other volume is inaccessible. In a &ldquo;links domino&rdquo; mode, access to all remotely mirrored volumes is denied when remote mirroring is disrupted by an all-links failure. The domino modes can be used to initiate application-based recovery, for example, recovering a secondary data file using a secondary log file. In an active migration mode, host processing of a primary volume is concurrent with migration to a secondary volume. In an overwrite cache mode, remote write-pending data in cache can be overwritten. Write data for an entire host channel command word chain is bundled in one link transmission.

Growing community of inventors

Brookline, MA, United States of America

Moshe Yanai