Storage virtualization systems and methods that allow customers to manage storage as a utility rather than as islands of storage which are independent of each other. A demand mapped virtual disk image of up to an arbitrarily large size is presented to a host system. The virtualization system allocates physical storage from a storage pool dynamically in response to host I/O requests, e.g., SCSI I/O requests, allowing for the amortization of storage resources through a disk subsystem while maintaining coherency amongst I/O RAID traffic. In one embodiment, the virtualization functionality is implemented in a controller device, such as a controller card residing in a switch device or other network device, coupled to a storage system on a storage area network (SAN). The resulting virtual disk image that is observed by the host computer is larger than the amount of physical storage actually consumed.

Storage virtualization system and methods

Performing data management operations on replicated data in a computer network. Log entries are generated for data management operations of an application executing on a source system. Consistency point entries are used to indicate a time of a known good, or recoverable, state of the application. A destination system is configured to process a copy of the log and consistency point entries to replicate data in a replication volume, the replicated data being a copy of the application data on the source system. When the replicated data represents a known good state of the application, as determined by the consistency point entries, the destination system(s) may perform a storage operation (e.g., snapshot, backup) to copy the replicated data and to logically associate the copied data with a time information (e.g., time stamp) indicative of the source system time when the application was in the known good state.

Systems and methods for performing data replication

A modular computer storage system and method is provided for managing and directing data archiving functions, which is scalable and comprehends various storage media as well as diverse operating systems on a plurality of client devices. A client component is associated with one or more client devices for generating archival request. A file processor directs one or more storage devices, through one or more media components, which control the actual physical level backup on various storage devices. Each media component creates a library indexing system for locating stored data. A management component coordinates the archival functions between the various client components and the file processor, including setting scheduling policies, aging policies, index pruning policies, drive cleaning policies, configuration information, and keeping track of running and waiting jobs.

Modular backup and retrieval system used in conjunction with a storage area network

A system and method are provided for performing storage operations relating to a first secondary copy of electronic data. A storage policy or storage preferences may dictate that a replication copy should be used in storage operations performed to a particular client, sub-client, data, media or other item. Based on the storage policy, when a new client, sub-client, data, media or other item is received, a media agent determines whether there is a replication copy of the item. In the absence of a replication copy, one may be created. The replication copy may be provided by a third party application, or created by the client or a storage management system component. Information regarding the replication copy and its corresponding first secondary copy may be stored in a database. To optimize use of system resources, storage operations relating to the first secondary copy may be performed using the replication copy instead of the first secondary copy.

Systems and methods for performing replication copy storage operations

Rolling cache configuration for a data replication system

A data processing system includes a data storage subsystem containing a plurality of data storage devices for reading and writing data on a plurality of data storage volumes. The data processing system is controlled by software to perform a method for recycling the data storage volumes containing a percentage of still valid data and a percentage of invalid data by transferring the still valid data on a plurality of input data storage volumes to one or more output data storage volumes. In accordance with the recycling method, the data processing system assigns a selected number of the data storage devices as input devices and a selected number of the data storage devices as output devices in a predetermined input/output ratio of the form m:k, where m is the number of input devices and k is the number of output devices. The system then commences transferring still valid data from input volumes mounted on the input devices to output volumes mounted on the output devices. As each volume is transferred, the system monitors the data transfer efficiency from the input devices to the output devices and adjusts the input/output ratio based on the measured data transfer efficiency.

Dynamic reconfiguration of data storage devices to balance recycle throughput

A record medium, such as a magnetic tape, optical disk, magnetic disk, and the like stores data signals and error redundancy signals Resynchronization signals are interleaved between the recorded signals such that the error redundancy signals are usable to correct signals recorded between such interposed resynchronization signals wherein no error redundancy signals are recorded Error pointing redundancy signals are recorded between all of the resynchronization signals for pointing to signals in error for enhancing the error correction Such error pointing signals can be cyclic redundancy check (CRC) signals Controls for taking advantage of the above-described arrangement are also described Reframing and clock synchronization controls are also disclosed

Enhanced data formats and machine operations for enabling error correction

A data storage system has error detecting and correcting system having three error codes. The data are arranged logically as a three-dimensional array consisting of a plurality of logically rectangular blocks of data. Each block of data has columns and rows of data. A first error code that corrects errors creates a first redundancy in each of the columns. A like-positioned block row of data in each of the blocks constitutes an array row of data. The array rows are grouped into sets of array rows, the number of array rows in each set vary inversely with a number of tracks of a record medium that concurrently receive the data for recording. Each set of data are recorded serially by bit in respective tracks of the tape record medium. Before recording, the block rows are logically rotated (end-around shifted) within each of the array rows. The block row shifting is different for each set such that the lateral alignment of data are changed for avoiding medium defects extending transversely of the tracks from creating excessive errors in any column of data. After the block row shifting, a second error code is applied to each block row while a third error code is applied to each array row. Readback is a reversal of the writing process. Error pointers are generated from the second and third redundancies as well as from signal and data format errors.

Error detection and correction having one data format recordable on record media using a diverse number of concurrently recorded tracks

Disclosed is a system for managing pages in a volatile memory device for data transfer operations between a first storage area and a second storage area. The first storage area is queried to determine a number of data sets to include in a data transfer operation. A number of pages in the volatile memory device needed for the data transfer operation is then determined. A determination is then made as to whether the number of pages needed for the data transfer operation is greater than available fixed pages in a pool of pages. Available fixed pages in the pool are allocated to the data transfer operation after determining that the number of pages needed to process the data transfer operation is less than or equal to the available fixed pages in the pool. Alternatively, after determining that the number of pages needed to process the data transfer operation is greater than the available fixed pages in the pool, all the fixed pages in the pool and additional fixed pages are allocated to the data transfer operation.

Management of fixed pages in memory for input/output operations

An inexpensive, high performance error detecting and correcting system capable of handling multiple errors with high throughput. Digital data is provided to a reconfigurable decoder which is initially set for a low level of correction and a high throughput. On detection of an error, a signal is generated which is used to dynamically reconfigure the decoder. The decoder is reconfigured at a higher correction level. The data is then reprocessed through the reconfigured decoder. In a specific implementation, the invention uses a Blahut decoder. N and K values to reconfigure the decoder are provided by a microprocessor. The invention contemplates use of an encoder operating at the highest level of correction required. Use of an initial low level of correction provides for a high throughput. Reconfigurability allows for high corrective power and associated lower throughput only when necessary.

Stephen Charles West

Papers

Dynamic reconfiguration of data storage devices to balance recycle throughput

Enhanced data formats and machine operations for enabling error correction

Error detection and correction having one data format recordable on record media using a diverse number of concurrently recorded tracks

Management of fixed pages in memory for input/output operations

Error correction method and system which selectively uses different levels of error correction to achieve high data throughput