Emc IP Holding Company LLC

Milind M Koli

Timothy C Ng

James Mark Holt

David Haase

Alan Lee Taylor

Xiangqing Yang

John H Lee

Vedashree Raman

Vedashree Anantha Raman

A method performed by a mapping driver executing on a DSS includes (a) receiving a data storage command that identifies a portion of storage of the DSS having a given size to which the data storage command is directed, (b) generating a plurality of derived data storage (DDS) instructions from the received data storage command, each DDS instruction of the plurality of DDS instructions identifying a respective sub-portion of the portion to which that DDS instruction is directed, each sub-portion having a respective sub-portion size smaller than the given size, and (c) issuing each DDS instruction separately to a data storage coordination driver also executing on the DSS, the data storage coordination driver being configured to cause each DDS instruction to be performed with respect to storage of the DSS. An apparatus, system, and computer program product for performing a similar method are also provided.

Techniques for splitting up I/O commands in a data storage system

In a data storage system a host I/O request is received from a host-side interface, the host I/O request specifying a range of logical block addresses (LBAs) of a mapped logical unit (MLU). Mapping information is obtained for a plurality of extents of the underlying logical units of storage. If there are a sufficient number of free sub-I/O request tracking structures to track completion of a plurality of respective sub-I/O requests for the extents, then the sub-I/O requests are concurrently issued to the device-side interface, using the mapping information. Upon receiving transfer initiation responses for the sub-I/O requests to initiate transfer of the respective extents, they are forwarded to the host-side interface to cause the respective extents to be transferred to/from the host. As the transfer initiation responses are forwarded to the host-side interface, the respective sub-I/O request tracking structures are freed for use in processing subsequent host I/O requests.

Managing dynamic resource reservation for host I/O requests

A method is provided for performance by an I/O Coordination module of a computing device operating as a data storage system in order to obtain and process physical extent mappings in the context of an XCOPY Lite or XCOPY type operation. The method involves breaking down the source region into physical source extents with reference to a container filesystem representing the logical volume of the source as a file. The I/O Coordination module is then able to separately process each of these physical source extents and also obtain its corresponding physical destination extents with reference to the container filesystem, which also represents the logical volume of the destination as a file. The I/O Coordination module is then able to cause integrated copy commands to be issued to an underlying physical storage driver. An apparatus, system, and computer program product for performing a similar method are also provided.

Techniques for performing data storage copy operations in an integrated manner

A method is provided for performance by a mapping driver of a computing device operating as a data storage system. The method includes (a) receiving, from a storage driver stack, a first data storage command (DSC), (b) receiving, from the storage driver stack, a second DSC, (c) determining that the first DSC and the second DSC are both related aspects of a combined storage command, (d) in response to determining, establishing a pairing structure to pair the first DSC and the second DSC together, and (e) fulfilling the combined storage command by fulfilling both the first DSC and the second DSC with reference to the pairing structure. An apparatus, system, and computer program product for performing a similar method are also provided.

Pairing of data storage requests

Data storage system with efficient processing of single mapping callback for host I/O requests

Techniques are provided for implementing a zero detection feature in the middle of a I/O driver stack that is able to function properly on migration of a thickly-provisioned logical disk to a thinly-provisioned logical disk. This may be accomplished by creating the destination thinly-provisioned logical disk with a Zero Detect mode that is initially set to active upon a migration. The zero detection feature implemented in the middle of the I/O driver stack is configured to require any writes to a logical disk to be buffered when that logical disk is in active Zero Detect mode, and to automatically apply zero detection to such writes to prevent writing entire blocks of zeroes. The Zero Detect mode may then be set to passive upon completion of the migration, allowing zero detection to be applied only to select write operations in the normal course of operation.

Techniques for migrating to a thinly-provisioned logical disk without writing zero blocks

A technique for use in managing data storage in a data storage system is disclosed. A first and second data storage commands (DSC) are received from a storage driver stack. Determining if the first DSC and the second DSC are both related aspects of a combined storage command and if so, establishing a pairing structure to pair the first DSC and the second DSC together. Fulfilling the combined storage command by fulfilling both the first DSC and the second DSC with reference to the pairing structure.

Technique for copying unallocated logical regions of thin logical units

A method in a data storage system includes receiving a host I/O request from a host-side interface specifying a range of logical block addresses (LBAs) of a mapped logical storage unit (MLU) mapped through a device-side interface to underlying units of storage. Mapping information is obtained for extents of the underlying logical storage units mapped to sub-ranges of the range of LBAs. Sub-I/O requests for the extents are concurrently issued to the device-side interface based on the mapping information, subject to a throttling mechanism to manage performance. The device-side interface provides transfer initiation responses to initiate transfer of the extents, the responses being forwarded to the host-side interface to cause the host-side interface to transfer the extents in a transfer phase. The transfer initiation responses may be re-ordered as necessary to enable the host-side interface to transfer the extents in address order in satisfaction of the host I/O request.

Data storage system with dynamic throttling of parallel sub-I/O request for individual host I/O requests

A method in a data storage system includes receiving a host I/O request from a host-side interface that specifies a range of logical block addresses (LBAs) of a mapped logical unit (MLU) of storage that is mapped through a device-side interface to underlying logical units of storage. Mapping information is obtained for extents of the underlying logical units of storage mapped to sub-ranges of the range of LBAs. Sub-I/O requests for the extents are concurrently issued to the device-side interface based on the mapping information. The device-side interface provides transfer initiation responses to initiate transfer of the extents, the responses being received and forwarded to the host-side interface to cause the host-side interface to transfer the extents in a transfer phase. The transfer initiation responses may be re-ordered as necessary to enable the host-side interface to transfer the extents in address order in satisfaction of the host I/O request.

Data storage system with parallel handling of sub-I/O requests for individual host I/O requests

An improved technique involves managing conflicts over data changes between a data change initiator and multiple listeners to allow any of the listeners to prevent the initiator from changing data. Along these lines, a data change notification process resides in a storage processor in memory outside of an I/O stack in which the listeners and data change initiators reside. When a data change initiator prepares to perform a data change operation, it notifies the data change notification process. The data change notification process in turn sends a notification to the listeners that have registered with the data change notification process. If there is a peer data change notification process on another storage processor, the data change notification process sends a notification to that peer data change notification process so that the peer data change notification process may notify its registered listeners.

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Morrisville, NC, United States of America

Milind M Koli