Emc Corporation

Other

Emx Corporation

Emc Corporatiion

Yuval Ofek

Natan Vishlitzky

Dan Arnon

Moshe Yanai

Mathieu Gagne

Eitan Bachmat

Gadi G Shklarsky

Douglas Eric LeCrone

Haim Kopylovitz

Zoran Cakeljic

Bruno Alterescu

Adi Ofer

Robert S Mason, Jr

Ruben Michel

Daniel Castel

Tao Kai Lam

Samuel Krikler

Victoria Dubrovsky

Daniel A Murphy

Daniel Lambright

Sharon Galtzur

Michael Hirsch

David Lionel Black

Haim Bitner

Eli Shagam

Robert A Thibault

Richard Wheeler

Nadav Kedem

Moshe Schreiber

Erez Ofer

John T Fitzgerald

Philip E Tamer

Peter Kamvysselis

Ishay Kedem

Ariel J Ish-Shalom

Stephen D MacArthur

Ramprasad Shetty

Avinoam Zakai

Daniel D C Castel

Stephen D Macarthur

Douglas E Lecrone

A data storage facility for transferring data from a data altering apparatus, such as a production data processing site to a remote data receiving site. The data storage facility includes a first data store for recording each change in the data generated by the data altering apparatus. A register set records each change on a track-by-track basis. A second data store has first and second operating modes. During a first operating mode the second data store becomes a mirror of the first data store. During a second operating mode the second data store ceases to act as a mirror and becomes a source for a transfer of data to the data receiving site. Only information that has been altered, i.e., specific tracks that have been altered, are transferred during successive operations in the second operating mode. Commands from the local production site initiate the transfers between the first and second operating modes.

Method and apparatus for cascading data through redundant data storage units

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 system interface includes a plurality of first directors, a plurality of second directors, a data transfer section and a message network. The data transfer section includes a cache memory. The cache memory is coupled to the plurality of first and second directors. The messaging network operates independently of the data transfer section and such network is coupled to the plurality of first directors and the plurality of second directors. The first and second directors control data transfer between the first directors and the second directors in response to messages passing between the first directors and the second directors through the messaging network to facilitate data transfer between first directors and the second directors. The data passes through the cache memory in the data transfer section. A method for operating a data storage system adapted to transfer data between a host computer/server and a bank of disk drives. The method includes transferring messages through a messaging network with the data being transferred between the host computer/server and the bank of disk drives through a cache memory, such message network being independent of the cache memory.

Data storage system having separate data transfer section and message network

Method and apparatus are disclosed for a computer system including host computers and storage elements. The host computers may be configured into a host domain and the storage elements configured into a storage domain. The storage domain includes a plurality of primary storage devices and a secondary storage device. The secondary storage device may be coupled to a plurality of the primary storage devices through a network. In another embodiment, the secondary storage device may send and receive information from a heterogeneous set of host computers. In another embodiment, connections for transfer of data onto the secondary storage element are created automatically.

Apparatus and methods for operating a computer storage system

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 system interface includes a plurality of first director boards. Each one of the first director boards has a plurality of first directors and a crossbar switch having input/output ports coupled to the first directors on such one of the first director boards and a pair of output/input ports. The system interface also includes a plurality of second director boards. Each one of the second directors boards has a plurality of second directors and a crossbar switch having input/output ports coupled to the second directors on such one of the second director boards and a pair of output/input ports. A data transfer section is provided having a cache memory. The cache memory is coupled to the plurality of first and second directors. A message network is operative independently of the data transfer section. The message network includes a pair of message network boards. Each one of such message network boards has a switching network having a plurality input/output ports. Each one of such pair of input/output ports is coupled to a corresponding one of the pair of output/input ports of the crossbar switches of the plurality of first director boards and the plurality of second director boards. The first and second directors control data transfer between the first directors and the second directors in response to messages passing between the first directors and the second directors through the message network to facilitate data transfer between first directors and the second directors. Data passes through the cache memory in the data transfer section. Each one of the directors includes: a data pipe coupled between an input of such one of the second directors and the cache memory; a microprocessor. A controller is coupled to the microprocessor and the data pipe for controlling the transfer of the messages between the message network and such one of the second directors and for controlling the data between the input of such one of the second directors and the cache memory.

Data storage system having separate data transfer section and message network with plural directors on a common printed circuit board and redundant switching networks

Method and apparatus are disclosed for copying and backing up logical objects in a computer storage system. The logical objects are comprised of data blocks. The data blocks may be copied in any order. The data blocks may be copied or written from a storage media, such as a tape, in parallel.

Apparatus and methods for copying, backing up and restoring logical objects in a computer storage system by transferring blocks out of order or in parallel

A method and apparatus for assuring data consistency in a data processing network including local and remote data storage controllers interconnected by independent communication paths. The remote storage controller or controllers normally act as a mirror for the local storage controller or controllers. If, for any reason, transfers over one of the independent communication paths is interrupted, transfers over all the independent communication paths to predefined devices in a group are suspended thereby assuring the consistency of the data at the remote storage controller or controllers. When the cause of the interruption has been corrected, the local storage controllers are able to transfer data modified since the suspension occurred to their corresponding remote storage controllers thereby to reestablish synchronism and consistency for the entire dataset.

Method and apparatus for maintaining data coherency

Storing data in a cache memory of a storage device includes providing access to a first segment of the cache memory on behalf of a first group of external host systems coupled to the storage device and providing access to a second segment of the cache memory on behalf of a second group of external host systems coupled to the storage device, where at least a portion of the second segment of the cache memory is not part of the first segment of the cache memory. In some embodiments, no portion of the second segment of the cache memory is part of the first segment. Storing data in a cache memory of a storage device may also include providing a first data structure in the first segment of the cache memory and providing a second data structure in the second segment of the cache memory, where accessing the first segment includes accessing the first data structure and accessing the second segment includes accessing the second data structure. The data structures may be doubly linked ring lists of blocks of data. Each block of data may correspond to a track on a disk drive. Different groups of external host systems may be provided with different access, priority, and level of service with respect to the different segments of the cache.

Segmenting cache to provide varying service levels

In a system that includes a back-up subsystem comprising back-up media, a mass storage subsystem connected to the back-up subsystem, and a host connected to the mass storage subsystem, the mass storage subsystem, as master and independent of the host, requests the restore operation by providing to the back-up subsystem, as slave, data identifiers identifying multiple data items to be transferred during the restore operation. The back-up subsystem determines its preferred ordering for retrieval of the requested plurality of data items from the back-up media. The back-up subsystem provides the requested data items to the mass storage subsystem in the determined preferred order in a plurality of iterations, each iteration identified by a data item identifier for the data item to be transferred in the current iteration.

System and method for restoring previously backed-up data in a mass storage subsystem

Load balancing of activities on physical disk storage devices is accomplished by monitoring reading and writing operations to blocks of contiguous storage locations on the physical disk storage devices. A list of exchangeable pairs of blocks is developed based on size and function. Statistics accumulated over an interval are then used to obtain access activity values for each block and each physical disk drive. A statistical analysis leads to a selection of one block pair. After testing to determine any adverse effect of making that change, the exchange is made to more evenly distribute the loading on individual physical disk storage devices.

Load balancing on disk array storage device

A data network with data storage facilities for providing redundant data storage and for enabling concurrent access to the data for multiple purposes. A first data processing system with a first data facility stores a data base and processes transactions or other priority applications. A second data storage facility, that may be physically separated from the first data storage facility, mirrors the data in the first data storage facility. In a concurrent access operating mode, the second data storage facility makes the data available to an application concurrently with, but independently of, the operation of the other application. On completion of the concurrent operation, the second data storage facility can reconnect with and synchronizes with the first data storage facility thereby to reestablish the mirroring operation.

Method and apparatus for independent and simultaneous access to a common data set

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

Growing community of inventors

Framingham, MA, United States of America

Yuval Ofek