Abstract: Described are techniques for determining connectivity. Statistics are received regarding components of the data storage system including any of a target port, a front end adapter, and a device. It is determined in accordance with inputs whether to modify existing connectivity between an initiator set of one or more initiators and a target set of one or more target ports of the data storage system. The inputs include the one or more statistics and one or more adjustment criteria. Responsive to determining to modify the existing connectivity, first processing makes modification(s) to the existing connectivity including any of: modifying an access state associated with a target port over which a device is exposed to an initiator, and adding or removing connectivity between the initiator and another target port of the data storage system where a device is exposed to the initiator over the another target port.

Abstract: Described are techniques for automatically configuring target port settings. A set of target port settings of a target port of a data storage system is initialized in accordance with a first target port setting configuration. It is determined whether the data storage system supports host registration. If the data storage system supports host registration, first processing is performed that includes registering a first host with the data storage system, wherein registering includes sending first information from the first host to the data storage system, the first information being sent from an initiator port of the first host to the target port; determining, using the first information, whether the set of target port settings of the target port require modification for use by the first host; and modifying the set of target port settings in accordance with the first information if the set of target port settings require modification.

Abstract: Described are techniques for caching metadata. At least a portion of the cached metadata may be stored persistently on flash-based storage. A data movement granularity size may be determined in accordance with one or more values including M denoting a number of storage units, or more generally metadata objects, having associated metadata stored in a single cached metadata page. At least a portion of the associated metadata is stored on the flash-based storage. A first data portion selected for data movement may have a size equal to the data movement granularity size. The first data portion has first metadata stored on the flash-based storage. The first metadata may include location metadata updated in connection with data movements performed. In accordance with data movement of the first data portion, the first metadata is updated. In a single write operation, the updated first metadata may be written to the flash-based storage.

Abstract: Described are techniques for automatically configuring target port settings. A set of target port settings of a target port of a data storage system is initialized in accordance with a first target port setting configuration. It is determined whether the data storage system supports host registration. If the data storage system supports host registration, first processing is performed that includes registering a first host with the data storage system, wherein registering includes sending first information from the first host to the data storage system, the first information being sent from an initiator port of the first host to the target port; determining, using the first information, whether the set of target port settings of the target port require modification for use by the first host; and modifying the set of target port settings in accordance with the first information if the set of target port settings require modification.

Abstract: Migrating data from a source storage device to a target storage device includes creating new paths to the target storage device, setting the target storage device to a state where I/O operations are initially accepted, where accepted I/O operations are rejected some time after acceptance, setting the source storage device to a state where at least some I/O operations are rejected, transferring metadata corresponding to the source storage device to the target storage device, where state information is transferred from the source storage device to the target storage device and setting the target storage device to a state where I/O operations are accepted and performed. Migrating data from a source storage device to a target storage device may also include creating new volumes on the target storage device and transferring data from the source storage device to the target storage device.

Abstract: Described are techniques for migrating data from a source device of a source data storage system to a target device of a target data storage system. The target data storage system is configured to operate in accordance with a spoofing mode and a pass-through mode. A first set of commands from the host are processed for the target device when in the pass-through mode and the spoofing mode with respect to the target device. Data is migrated from the source device to the target device. The target data storage system is configured to operate in an echo mode for the target device and processes a second set of commands from the host when in the echo mode for the target device using information stored in the cache from processing the first set of commands.

Abstract: Described are techniques for storage configuration. Defined are one or more initiator groups each including one or more initiator ports, one or more target groups each including one or more target ports, and one or more storage groups each including one or more devices. A masking view is created where the masking view includes a first of the initiator groups, a first of the target groups, and a first of the storage groups. The masking view indicates which devices of the first storage group are accessible using one or more paths. Each of the one or more paths is specified using an initiator port from the first initiator group and a target port from the first target group.

Abstract: Described are techniques for representing and using RAID group consistency information. RAID group consistency information for a slice of data included on a device may be obtained by mapping the slice to an index. The index is one of a plurality of indices each associated with a structure indicating RAID group inconsistencies for a different portion of slices of data of the device. If the index is not associated with a structure, it may be determined that there is no RAID group inconsistency for the slice. If the index is associated with a structure, a hint bit associated with the slice may be determined wherein the hint bit encodes summary consistency information for a plurality of slices. A determination is made as to whether the hint bit is set, and, if the hint bit is not set, it is determined that there is no RAID group inconsistency for the slice.

Abstract: Described are techniques for storage configuration. Defined are one or more initiator groups each including one or more initiator ports, one or more target groups each including one or more target ports, and one or more storage groups each including one or more devices. A masking view is created where the masking view includes a first of the initiator groups, a first of the target groups, and a first of the storage groups. The masking view indicates which devices of the first storage group are accessible using one or more paths. Each of the one or more paths is specified using an initiator port from the first initiator group and a target port from the first target group.

Abstract: Embodiments of the invention exploit the fact that not all portions of a logical volume may include data written by a host. Accordingly, an embodiment of the invention includes setting a designated set of bits to 1 in a meta data table when a logical volume is initialized. These bits may be referred to herein as Never Written by Host (NWBH) bits. Separately, or in combination, an embodiment of the invention includes setting a NWBH bit to 0 when data is written to the associated portion of the logical volume. Separately, or in combination, an embodiment of the invention includes reading the NWBH bit upon receiving a read command associated with the associated portion of the logical volume. If the NWBH bit is equal to 1, data is not read from the associated portion of the logical volume; if the NWBH bit is equal to 0, data is read from the associated portion of the logical volume.

Abstract: A partitioned storage subsystem includes a plurality of directors, each having at least one processor thereon, each of the directors acting as one of: a primary director and a secondary director for a subset of logical devices handled by the partitioned storage subsystem, where primary directors actively perform I/O operations for logical devices and wherein secondary directors receive data to mirror memory of a corresponding primary director. The partitioned storage subsystem also includes a global memory distributed among the plurality of directors, where a different portion of the global memory is provided on each of the directors, and includes metadata for the logical devices, provided in the global memory, where the metadata contains information that correlates logical device data with physical device data. The physical device data may be provided by at least one disk drive coupled to at least one of the directors.

Abstract: Described are techniques for storage configuration. Defined are one or more initiator groups each including one or more initiator ports, one or more target groups each including one or more target ports, and one or more storage groups each including one or more devices. A masking view is created where the masking view includes a first of the initiator groups, a first of the target groups, and a first of the storage groups. The masking view indicates which devices of the first storage group are accessible using one or more paths. Each of the one or more paths is specified using an initiator port from the first initiator group and a target port from the first target group.

Abstract: A storage array includes a plurality of directors, each having at least one processor thereon and a global memory distributed among the plurality of directors. A different portion of the global memory is provided on each of the directors. A interconnect fabric is coupled to each of the directors. Global memory accesses performed by one director to access memory of another director through the interconnect fabric. The storage array also includes a plurality of partitioned storage subsystems, each including a separate subset of the directors, where each of the partitioned storage subsystems handles I/O operations for a plurality of logical devices independently of I/O operations for logical devices of other ones of the partitioned storage subsystems, the I/O operations using metadata provided in the global memory of the corresponding directors and containing information that correlates logical device data with physical device data.

Abstract: Handling I/O operations for a storage array includes distributing metadata among separate memories of a plurality of directors of the storage array, where the metadata correlates logical device data with physical device data. A first one of the directors receives an I/O operation for a particular logical device. Handling I/O operations may also include determining which of the plurality of directors contains metadata corresponding to the particular logical device, and, in response to the metadata being on a different one of the directors, the first director providing a request to the different one of the directors. The directors may be interconnected by an interconnect fabric. The first one of the directors may provide a request to the second one of the directors via the interconnect fabric. Determining which of the plurality of directors contains metadata correspond to the particular logical device may include using a lookup table.

Abstract: A system for de-duplicating data includes providing a first volume including at least one pointer to a second volume that corresponds to physical storage space, wherein the first volume is a logical volume. A first set of data is detected as a duplicate of a second set of data stored on the second volume at a first data chunk. A pointer of the first volume associated with the first set of data is modified to point to the first data chunk. After modifying the pointer, no additional physical storage space is allocated for the first set of data.

Abstract: Described are techniques for initializing a device in a data storage system. An indicator is set in an entry associated with a portion of the device indicating that the portion of the device is to be initialized. A signature field of the entry is set with a signature value indicating that the portion of the device is to be initialized. The device is indicated as available for use after setting the indicator and the signature field for each portion of the device. The device has one or more portions and each of the portions has a corresponding entry including an indicator and a signature field.

Abstract: Described are techniques for overriding an existing device reservation. Discovery processing is performed by a first data storage system to locate a specified device. The discovery processing includes determining whether there is a reservation conflict for said device of a second data storage system. If there is a reservation conflict for the device, a command is issued from the first data storage system to the second data storage system during said discovery processing to create an override for said reservation conflict. The override causes processing to be performed at a subsequent point in time so that an existing reservation associated with the reservation conflict is overridden in connection with performing a first process on said first data storage system.

Abstract: Two data operations, such as write operations, may be processed at a same time in which the two write operations operate on a same address range span. A first of the write operations may write to the first track and the last track in the span but not tracks therebetween. When processing the first write operation, a lock for the first track is obtained and the data is written to the first track data. A lock for the last track is obtained and it is determined whether all tracks between the first and last tracks are unlocked. If so, data is written to the last track. If not, steps of releasing and then reacquiring the lock for the last track and determining whether intervening tracks are locked are repeated until the intervening tracks are not locked. The last track is then written.