A data storage system which automatically provides and maintains identical secondary data on a preferably geographically remote secondary data storage device. The system includes a primary host computer located in the first geographic location which is coupled to a primary data storage system also located in the first geographic location. The primary data storage system includes at least one primary data storage device on which primary data is to be stored, and a primary data storage system controller which receives data from the primary host computer and controls the storing of the primary data on the primary data storage device. The primary data storage controller is coupled by high speed communication link to a secondary data storage system controller of a secondary data storage system, and coordinates the copying of the primary data to the secondary data storing system, and is responsive to an acknowledgement from the secondary data storage system controller of at least successful receipt of the primary data for updating the maintained list of the primary data to indicate that the copied primary data has been received by the secondary data storage system to be copied to the secondary data storage device.

Remote data mirroring

A data storage system has a primary data storage subsystem including primary data storage and a secondary data storage subsystem including secondary data storage. The secondary data storage contains backup versions of data stored in the primary data storage. To permit a host processor to access a specified backup version, the primary data storage subsystem assigns a virtual storage address to a specified backup version, and the host processor sends to the primary data storage subsystem data access requests that specify the virtual storage address. If the primary data storage subsystem has spare data storage, then a copy of the specified backup version is read from the secondary storage and written into the spare storage, and the address of the copy in the spare storage is mapped to the virtual storage address and accessed in response to the storage access requests from the host processor. Otherwise, a block-level direct access of the secondary storage is performed to access the specified backup version. In either case, the backup version appears to be in the primary data storage subsystem when the host accesses it.

Virtual storage and block level direct access of secondary storage for recovery of backup data

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 data link to a corresponding secondary volume. The host computer sends chains of channel commands to the data storage system containing a primary (R1) volume of a remotely mirrored volume pair. In order to more effectively use the capacity of the data link, the data storage system containing the primary (R1) volume bundles the write data for all write commands in the chain into a single write command for transmission over the data link to the secondary data storage system containing the secondary (R2) volume. The data storage system containing the primary (R1) volume decodes the channel commands to determine when it has received the last channel command in the chain, and once the last channel command in the chain is received, it transmits the bundle of write data for the chain over the data link to the data storage system containing the secondary (R2) volume. In a preferred implementation, the write data is stored in a cache memory in the data storage system containing the primary (R1) volume, and the data storage system containing the primary (R1) volume bundles the write data by accumulating, in a buffer, pointers to the write data in the cache memory.

Bundling of write data from channel commands in a command chain for transmission over a data link between data storage systems for remote data mirroring

In one embodiment of the present invention, a memory storage system for storing information organized in sectors within a nonvolatile memory bank is disclosed. The memory bank is defined by sector storage locations spanning across one or more rows of a nonvolatile memory device, each the sector including a user data portion and an overhead portion. The sectors being organized into blocks with each sector identified by a host provided logical block address (LBA). Each block is identified by a modified LBA derived from the host-provided LBA and said virtual PBA, said host-provided LBA being received by the storage device from the host for identifying a sector of information to be accessed, the actual PBA developed by said storage device for identifying a free location within said memory bank wherein said accessed sector is to be stored. The storage system includes a memory controller coupled to the host; and a nonvolatile memory bank coupled to the memory controller via a memory bus, the memory bank being included in a non-volatile semiconductor memory unit, the memory bank has storage blocks each of which includes a first row-portion located in said memory unit, and a corresponding second row-portion located in each of the memory unit, each of the memory row-portions provides storage space for two of said sectors, wherein the speed of performing write operations is increased by writing sector information to the memory unit simultaneously.

Increasing the memory performance of flash memory devices by writing sectors simultaneously to multiple flash memory devices

A method and apparatus for transferring data between two storage media, and is used in an illustrative embodiment to transfer data between two storage media in a shadow set, the storage media being accessible to one or more host processors. The method of the preferred embodiment includes the steps of: A. receiving a command from one of the host processors, the command specifying data to be transferred from a first storage medium to a second storage medium; B. transferring the data specified in the command received from the host from the first storage medium to the second storage medium in a series of subtransfers, each of the subtransfers transferring a portion of the data; and C. processing one or more I/O requests to the shadow set received from one or more host processors by, for each received I/O request: a. implementing the I/O request if the I/O request does not involve a section of the shadow set currently involved in one of the subtransfers; and b. stalling the I/O request if the I/O request involves a section of said shadow set currently involved in one of the subtransfers, and implementing the I/O request when the subtransfer has completed.

Transferring data in a digital data processing system

A buffered cache memory subsystem is disclosed which features a solid-state cache memory connected to a storage director which interfaces a host channel with a control module controlling operation of a long-term data storage device such as a disk drive. The solid-state cache memory is connected to plural directors which in turn may be connected to differing types of control modules, whereby the cache is usable with more than one type of long-term data storage means within a given system. The cache memory may be field-installed in a preexisting disk drive storage system and is software transparent to the host computer, while providing improvements in overall operating efficiency. In a preferred embodiment, data is only cached when it is expected to be the subject of a future host request.

Cache buffered memory subsystem

of the Disclosure A method of operation of a memory array for storage of records of differing predetermined sizes is disclosed which features division of the array into domains which are substantially integral multiples of the predetermined record sizes. In a preferred embodiment the domain allocation may be varied adaptively in accordance with usage so as to enable more fully efficient use of the array.

Adaptive domain partitioning of cache memory space

A host connected outboard back-up and recovery system has a tape drive connected to a plural port solid-state cache memory which, in turn, is connected to a disk drive. Data to be backed-up can first be copied from the disk drive to the cache and then from the cache to the tape drive in back-up operations, so that the relative speeds of the disk drive and the tape need not be matched. An outboard controller controls flow of the data between the disk drive and the tape drive and additionally controls storage of the data on the tape, so that host computer involvement is avoided.

Outboard back-up and recovery system with transfer of randomly accessible data sets between cache and host and cache and tape simultaneously

A method for detection of a sequential data stream which can be performed without host computer intervention is disclosed featuring examination of a data record and channel program during read operations for signals indicative that the data is not part of a sequential data stream, for example, embedded seek instructions. If a particular sought for record does not contain such indications, the successive record or records may then be staged to a faster access memory device such as a solid-state cache. The invention is described in a plug-compatible, software-transparent configuration.

Detection of sequential data stream for improvements in cache data storage

A method for detection of a sequential data stream which can be performed in a data storge subsystem without host computer intervention is disclosed featuring examination of the channel program processed during a read operation for signals indicative that the data is not part of a sequential data stream, for example, embedded seek instructions. If a particular channel program for does not contain such indications, the successive record or records may then be staged to a faster access memory device such as a solid-state cache. The invention is described in a plug-compatible, software-transparent configuration.

P. David Dodd

Papers

Cache buffered memory subsystem

Adaptive domain partitioning of cache memory space

Outboard back-up and recovery system with transfer of randomly accessible data sets between cache and host and cache and tape simultaneously

Detection of sequential data stream for improvements in cache data storage

Detection of sequential data stream