Abstract: A method and apparatus are provided for printing multicolored three-dimensional objects. The method includes: selectively exposing a photosensitive thermoplastic feedstock to light within an extrusion nozzle, the feedstock comprising a thermoplastic base mixed with a photosensitive material; extruding the exposed feedstock into a deposit to print an object; and photo-chemically developing the deposit to provide color to the deposit. An apparatus is provided for three-dimensional printing with an extrusion nozzle including a light exposing component for selectively exposing the photosensitive thermoplastic feedstock to light within the extrusion nozzle.

Abstract: A surface portion modification apparatus is provided which is co-operable with a 3D printer. It includes a head nozzle follower assembly. The follower assembly is co-operable with a 3D printer head nozzle assembly and is operable for modifying at least a portion of a surface of the material of a 3D object printed by the head nozzle assembly of the 3D printer. It may be used to smooth the surface of an object printed by the 3D printer.

Abstract: It is determined that a cache operation relating to the transfer of data between a cache memory and a data storage system is required. A state of a utilization model is received, the utilization model including requirements for utilization of resources of the data storage system over a time period, and the state indicating a cost of resource utilization associated with cache operations in the current time period. It is determined whether to perform the cache operation, based on the utilization requirements and the state of a utilization model. If the cache operation is not to be performed, and if the cache operation is a write operation, it is determined whether the cache memory is full. If so, the cache operation is managed according to an emergency cache management process; if not, the data associated with the cache operation is maintained in the cache memory.

Abstract: A fault-tolerant storage system includes a first strand comprising a first initiating device connected to a first expansion device of a first set of serially connected expansion devices, a second strand comprising a second initiating device connected to a first expansion device of a second set of serially connected expansion devices, and a plurality of zoning switches that each connect an expansion device in the first set of serially connected expansion devices to a corresponding expansion device in the second set of serially connected expansion devices. A computer program product and method executed by a computer corresponding to the above system are also disclosed herein.

Abstract: A system comprises a video hosting subsystem configured to access a database of video streams. The video hosting subsystem comprises a processor for processing data associated with the video streams, and memory for storing data. The processor is configured to receive a user request to access a selected primary video stream. The processor is further configured to identify other video streams captured at substantially the same time and location as the selected primary video stream and in which a person specified in the user request appears. The processor is configured to select, from the identified other video streams, an alternative video stream. The processor is further configured to provide the user with access to the selected primary video stream, together with an option to access the alternative video stream.

Abstract: A mechanism is provided for backing up metadata in a data storage system. Given metadata stored on the data storage system is implemented by way of a tree structure operable by fixed mapping. A stream of snapshots is taken of leaves in the metadata tree structure of given metadata stored on persistent data storage. The metadata tree structure of the given metadata stored on the persistent data storage is reconstructed on a basis of the stream of snapshots taken for backing up the given metadata stored on the persistent data storage. A journal over the reconstructed metadata tree structure is then replayed. In response to a given status discrepancy being flagged in respect of any given metadata, the status of a given leaf corresponding thereto in the reconstructed data tree structure is modified for consistency with the corresponding journal entry in the journal for that given metadata.

Abstract: A method for reducing I/Os to a redundant array of independent disks (RAID) is disclosed. In one embodiment, such a method includes receiving a write request comprising new data for overwriting corresponding old data in cache. The method performs an XOR (exclusive OR) operation on the new data and the old data to yield a parity delta and overwrites, in the cache, the old data with the new data. In certain embodiments, the XOR operation is performed prior to overwriting the old data with the new data. The method further stores the parity delta in the cache and links the parity delta to the new data. Upon destaging the new data from the cache, the method provides the parity delta with the new data so that the parity delta may be applied to an existing parity value in the RAID. A corresponding system and computer program product are also disclosed.

Abstract: This invention relates to a system, method and computer program product for a drive array controller (for example a RAID6 controller) comprising: a failed strip identifier for identifying a failed strip in a critical stride strip in drive array when the drive array has two or more failed drives, a critical stride is a stride with two (for example) failed strips, a failed strip is a strip in a failed drive, a failed drive is a drive that can no longer be reliably used; a safe strip identifier for identifying a safe strip in a safe stride, a safe stride is a stride with no failed strips (or at least two less than a critical stride), a safe strip is a strip in a safe stride; a drive array writer for writing a recalculated failed strip to the drive array location for the safe strip; and a lending table writer for writing the failed strip location and associated safe strip location to a lending table.

Abstract: This invention relates to a storage system, storage system method and computer program product comprising: providing a distributed collection of drives, each drive having logical blocks, each logical block being assignable to a segment with an associated volume and being configurable to RAID characteristics associated with that volume; assigning a first group of logical blocks to a segment with an associated volume and configuring the first group of logical blocks to RAID characteristics associated with that volume; and wherein a further group of logical blocks is ready to be assigned to any segment but is not yet assigned.

Abstract: A RAID system includes a storage enclosure comprising a plurality of independent data storage devices. A processor is associated with the storage enclosure. The processor is configured for processing data for the plurality of storage devices of the storage enclosure. The processor is configured to receive a request to read intermediate XOR data based on data stored in two or more of the plurality of storage devices of the storage enclosure. The processor is further configured to read data from each of the two or more storage devices in response to receiving the request. The processor is configured to determine intermediate XOR data based on the data read from the two or more storage devices of the storage enclosure. The intermediate XOR data may be provided to a RAID storage controller and may be used in an XOR-based recovery process.

Abstract: This invention relates to a system, method, and computer program product for managing a plurality of devices with associated lock mechanisms. According to one embodiment, a method is provided comprising: detecting, by one or more computer processors, a status of a device corresponding to a lock mechanism; recommending, by one or more computer processors, a service action on the device requiring performance by an operator; and providing, by one or more computer processors, a printable key pattern for printing a key that allows the operator to lock and unlock the lock mechanism in order to perform the service action.

Abstract: This invention relates to a system, method, and computer program product for managing a plurality of devices with associated lock mechanisms. According to one embodiment, a method is provided comprising: detecting, by one or more computer processors, a status of a device corresponding to a lock mechanism; recommending, by one or more computer processors, a service action on the device requiring performance by an operator; and providing, by one or more computer processors, a printable key pattern for printing a key that allows the operator to lock and unlock the lock mechanism in order to perform the service action.

Abstract: A method and system are provided for spare capacity usage for critical redundancy in storage arrays. The method may include monitoring a Redundant Array of Independent Disks (RAID) array to determine whether one or more redundancy units are at a critical level. A redundancy unit may be in a critical level when an additional drive failure will result in loss of data from the redundancy unit. The method may further include identifying available regions in the RAID array which are not allocated to user data in response to determining that a particular redundancy unit is critical. The method may further include determining an available region for the particular redundancy unit, where the available region is in a drive of the RAID array that does not contain data of the particular redundancy unit. The method may further include storing a critical stripe in the available region.

Abstract: A method for balancing performance in a redundant array of independent disks (RAID) made up of heterogeneous storage drives is disclosed. In one embodiment, such a method includes implementing a RAID on a set of storage drives. The set of storage drives includes a lower-performing storage drive that underperforms other storage drives in the set. In order to balance performance in the RAID, the method stripes data across the set of storage drives such that the lower-performing storage drive participates in only a selected percentage of strides. In certain embodiments, this percentage is selected based on an amount the lower-performing storage drive underperforms other storage drives in the set. A corresponding system and computer program product are also disclosed.

Abstract: A method for recovering data in a redundant array of independent disks (RAID) is disclosed. In one embodiment, such a method includes implementing a RAID in a storage architecture comprising a RAID controller and a storage enclosure containing a set of storage drives belonging to the RAID. The RAID controller is configured to detect a failure condition associated with at least one of the storage drives in the set. In response to detecting the failure condition, the RAID controller sends, to the storage enclosure, an instruction to copy data from a first storage drive in the set to a second storage drive in the set as part of a RAID rebuild process. The storage enclosure receives the instruction and executes it without substantially involving the RAID controller in the copy process. A corresponding system and computer program product are also disclosed.

Abstract: A method of performing a data write on a storage device comprises instructing a device driver for the device to perform a write to the storage device, registering the device driver as a transaction participant with a transaction co-ordinator, executing a flashcopy of the storage device, performing the write on the storage device, and performing a two-phase commit between device driver and transaction co-ordinator. Preferably, the method comprises receiving an instruction to perform a rollback, and reversing the data write according to the flashcopy. In a further refinement, a method of scheduling a flashcopy of a storage device comprises receiving an instruction to perform a flashcopy, ascertaining the current transaction in relation to the device, registering the device driver for the device as a transaction participant in the current transaction with a transaction co-ordinator, receiving a transaction complete indication from the co-ordinator, and executing the flashcopy for the device.

Abstract: A method for regulating a flow of data to backend storage devices includes generating, at a host system, writes intended for a backend storage volume. The method receives the writes into a first level cache of a storage virtualization appliance. The method further determines whether destaging the writes directly from the first level cache to the backend storage volume would cause a limit associated with the backend storage volume to be exceeded. If destaging the writes directly from the first level cache to the backend storage volume would cause the limit to be exceeded, the method destages the writes from the first level cache to a second level cache of the storage virtualization appliance. Otherwise, the method destages the writes directly from the first level cache to the backend storage volume. A corresponding system and computer program product are also disclosed.

Abstract: A method for reducing I/Os to a redundant array of independent disks (RAID) is disclosed. In one embodiment, such a method includes receiving a write request comprising new data for overwriting corresponding old data in cache. The method performs an XOR (exclusive OR) operation on the new data and the old data to yield a parity delta and overwrites, in the cache, the old data with the new data. In certain embodiments, the XOR operation is performed prior to overwriting the old data with the new data. The method further stores the parity delta in the cache and links the parity delta to the new data. Upon destaging the new data from the cache, the method provides the parity delta with the new data so that the parity delta may be applied to an existing parity value in the RAID. A corresponding system and computer program product are also disclosed.

Abstract: A method for minimizing head seek movement and improving I/O performance of a hard disk drive is disclosed. In one embodiment, such a method includes logically dividing storage space of a hard disk drive into storage areas of substantially equal size. The method monitors a temperature of each of the storage areas. The temperature indicates how frequently data in a corresponding storage area is accessed. The method swaps data in storage areas of the hard disk drive based on temperature. These swaps involve moving hotter data toward outer tracks of the disk drive and colder data toward inner tracks of the disk drive. A corresponding system and computer program product are also disclosed.

Abstract: A method for recovering a failed storage drive in a redundant array of independent disks (RAID) includes storing, on a first distributed spare of the RAID, a first parity subset for a first set of drives in the RAID. The method further stores, on a second distributed spare of the RAID, a second parity subset for a second set of drives in the RAID. In the event a storage drive in the RAID fails, the method determines whether the storage drive belongs to the first set or second set. In the event the failed storage drive belongs to the first set, the method uses the first parity subset on the first set of drives in the RAID to recover the failed storage drive. In the event the failed storage drive belongs to the second set, the method uses the second parity subset on the second set of drives in the RAID to recover the failed storage drive. A corresponding system and computer program product are also disclosed.