Emc Corporation

Emc IP Holding Company LLC

Marc C Cassano

Robert Foley

Daniel E Cummins

Peter Puhov

David W Harvey

Ronald D Proulx

Socheavy D Heng

Jian Gao

Hongpo Gao

Lili Chen

Henry Austin Spang, Iv

Wei He

Zhipeng Hu

Disclosed herein are techniques for use in managing data storage. For example, in one embodiment, the techniques comprise determining a size of the write request. The size of the write request equating to half or more non-parity data portions in a full stripe of data but less than all non-parity data portions in the full stripe. The techniques comprise performing a process based on the size that includes reading a parity and one or more missing non-parity data portions in the full stripe, verifying the coherency of the missing non-parity data portions by comparing a checksum of the parity and a checksum of the missing non-parity data portions, determining a new parity based on the new data and the missing non-parity data portions, and writing, in response to verifying the coherency of the missing non-parity data portions, the new data and the new parity to a RAID group without writing the one or more missing non-parity data portions to the RAID group, wherein the new data and the new parity are written to the RAID group with a checksum.

Managing data storage

There are disclosed computer-implemented methods, apparatus, and computer program products for managing data storage. In one embodiment, the computer-implemented method comprises the step of receiving new data to be written to storage. The method also comprises the step determining that the new data does not form a full stripe of data. The method also comprises reading missing non-parity data in the stripe of data. The method further comprises determining new parity based on the new data and the missing non-parity data. The method still further comprises writing the new data and the new parity to storage in a manner that does not require the missing non-parity data to be written to storage.

A method, computer program product, and computing system for receiving an IO request for a RAID array. An actual queue depth of the RAID array is compared to a maximum queue depth for the RAID array. An IO queue weight is determined for the IO request. The IO queue weight is revised based upon a degrade mode condition for the RAID array, thus defining a revised IO queue weight. The actual queue depth is incremented based upon the revised IO queue weight.

IO request system and method

A method is used in managing mapping metadata in storage systems. A request is received to access data organized on a storage device of a storage system. Checksum information is used for validating the data. The checksum information is stored on the storage system separate from a location at which the data has been stored.

Managing mapping metadata in storage systems

A technique for managing storage device rebuild in a data storage system is disclosed. A RAID group having multiple drives with unique identifiers is provided. A drive in the RAID group that becomes inactive is identified and a timer is activated. A persistent bitmap is maintained, wherein the bitmap includes a plurality of bits and each bit indicates whether a corresponding portion of the identified drive has changed as a result of an I/O request issued while the drive is identified as inactive. If the inactive drive is subsequently identified as active before the timer expires, the timer is stopped and a rebuild procedure initiated, wherein only portions of the identified drive corresponding to bits in the bitmap are rebuilt. The bitmap is cleared and the RAID group is marked as healthy. If the timer expires before the identified drive become active, a full rebuild procedure is initiated.

Managing storage device rebuild in data storage systems

A method, computer program product, and computing system for sensing the occurrence of an degraded condition within a data stripe of a RAID array. The data strip includes one or more valid data portions, one invalid data portion, and a parity portion. A request to write updated content to a target data portion within the data stripe is received, wherein the target data portion is one of the valid data portions. The valid data portions and the parity portion are read from the data stripe. The invalid data portion is reconstructed using the valid data portions and the parity portion, thus generating a reconstructed data portion. The reconstructed data portion is stored within a mirrored cache memory system. The parity portion is updated to define the updated content, thus defining an updated parity portion. The updated parity portion is written to the data stripe and the updated content is written to the target data portion within the data stripe.

At risk data caching (ARDC)

A method is used in managing software errors in storage systems. It is detected that a first processor of a storage system has a problem performing an I/O on a logical object. The first processor has a first path to the logical object. The problem includes a software error. Whether responsibility of performing the I/O on the logical object is transferred to a second processor of the storage system is evaluated. The second processor has a second path to the logical object.

Managing software errors in storage systems

A method, computer program product, and computing system for sensing the occurrence of an uncorrectable condition within a data stripe of a RAID array. The data strip includes a plurality of data portions and a parity portion. One or more invalid data portions included within the plurality of data portions are identified. The one or more invalid data portions are populated with filler data having a known pattern, thus defining one or more filler portions. The parity portion is updated based, at least in part, upon the one or more filler portions, thus defining an updated data stripe that includes an updated parity portion.

Limiting data loss on parity RAID groups

Described are techniques for booting a data storage system. A first set of configuration and state information is read from first storage devices of a first RAID group using special processing code and a RAID library. A first set of system objects (of a system object topology) are instantiated using the first set of information. The first set of system objects represent storage entities containing a second set of configuration and state information. Using an I/O runtime stack based on the system object topology, the second set of information is read from second storage devices of a second RAID group using the same RAID library having calls made from method(s) of a RAID group object representing the second RAID group. A second set of client objects, instantiated using the second set of information, represent storage entities including client data stored on third storage devices of a third RAID group.

Data storage system configuration

Techniques for a method of processing events are described. A first notification is received regarding an occurrence of a first event identifying a first physical drive coming online. It is determined whether the first event is dependent on one or more other events that have not yet occurred. If it is determined that the first event depends on one or more other events that have not yet occurred, performing first processing to defer processing of the first event until the one or more other events have occurred. If it is determined that the first event does not depend on the one or more other events that have not yet occurred, the first event is processed.

Growing community of inventors

Medway, MA, United States of America

Marc C Cassano