Abstract: Examples include compressed pages having data and compression metadata. Some examples include receiving a write request containing write data, storing the write data in data cache, and applying a page fit process to the write data. In some such examples, a virtual page table entry in a virtual page table may be generated for the processed write data. The virtual page table entry may include a compression index and a page address. An inline compression of the processed write data may be performed to compress and store the processed write data in a compressed page at a location associated with the compression index. In some examples, the compressed page may include a compression metadata having a reference count, a compressed page offset, and a virtual page address.

Abstract: Examples include compressed pages having data and compression metadata. Some examples include receiving a write request containing write data, storing the write data in data cache, and applying a page fit process to the write data. In some such examples, a virtual page table entry in a virtual page table may be generated for the processed write data. The virtual page table entry may include a compression index and a page address. An inline compression of the processed write data may be performed to compress and store the processed write data in a compressed page at a location associated with the compression index. In some examples, the compressed page may include a compression metadata having a reference count, a compressed page offset, and a virtual page address.

Abstract: A system that includes a storage drive and a controller communicatively coupled to the storage drive. The storage drive includes a first region of storage space that is mapped to a virtual volume and at least a second region of storage space reserved for over-provisioning operations. The controller is to unmap an operable portion of the first region of storage space in response to aging of the storage drive so that the unmapped portion can be used for over-provisioning operations.

Abstract: A system that includes a storage drive and a controller communicatively coupled to the storage drive. The storage drive includes a first region of storage space that is mapped to a virtual volume and at least a second region of storage space reserved for over-provisioning operations. The controller is to unmap an operable portion of the first region of storage space in response to aging of the storage drive so that the unmapped portion can be used for over-provisioning operations.

Abstract: A data storage system having a host computer/server coupled to a bank of disk drives through an interface. The bank of disk drives has a plurality of disk units, each one of such disk drive units having a magnetic storage media. The interface includes: a plurality of front-end directors coupled to the host computer/server; a plurality of back end directors coupled to the disk drive units; and, a global cache memory available for caching user data for the plurality of disk drives. The global cache memory comprises a plurality of non-volatile memory global cache memory sections distributed among disk drive units within the bank of disk drive units. The non-volatile memory global cache memory sections are connected to the back-end directors. Each one of the non-volatile memory global cache memory sections caches user data for the magnetic storage media of the plurality of disk drive units independent of the one of the disk drive units having such one of the non-volatile memory global cache memory sections.

Abstract: A system is used in caching with flash-based memory. First and second controllers communicate with a flash-based cache. A magnetic disk array is in communication with the flash-based cache. The flash-based cache has a dual ported link to the first and second controllers. The flash-based cache has flash-based memory components arranged in a RAID data protection scheme.

Abstract: Scheduling jobs for a plurality of logical devices associated with physical devices includes assigning a physical run count value and a physical skip count value to each of the physical devices, at each iteration, examining the physical skip count value and the physical run count value for each of the physical devices, and scheduling a number of jobs up to the physical run count value for logical devices associated with a particular one of the physical devices at each iteration corresponding to the physical skip count value for the particular one of the physical devices. The physical skip count value and the physical run count value for a particular one of the physical devices may vary according to a total load of the particular physical device.

Abstract: Scheduling jobs for a plurality of devices includes assigning a run count value to each of the devices, scheduling a number of consecutive jobs up to the run count value, and decrementing the run count value according to the number of consecutive jobs scheduled. The run count value for a particular one of the devices may vary according to a total load of the particular one of the devices. The total load of the particular device may vary according to a number of pending jobs for the particular device and a total number of jobs for all devices coupled to a controller for the devices. The devices may be disk drive devices. Only one read job may be scheduled for a device irrespective of the run count value for the device and devices having pending read jobs may be given precedence over other devices. Multiple read jobs may be scheduled for a device according to the run count value and devices having pending read jobs may be given precedence over other devices.

Abstract: A method is used in managing mirroring in data storage system having a fast write device and a slow write device. A write I/O is received and is executed on the fast write device which includes a solid state drive. The write I/O is stored in interim storage having high performance sequential write capability. It is indicated that execution of the write I/O is complete. Based on the interim storage, the write I/O is executed on the slow write device.

Abstract: Described is a storage system and method for managing and optimizing power consumption in a storage system. Logical devices are mapped to physical disk drives. A plurality of power profiles is defined. Each power profile is associated with a mode of operation for a physical disk drive. One of the power profiles is assigned to each logical device. One of the physical disk drives is identified for which every logical device mapped to that physical disk drive has been assigned the same power profile. The identified physical disk drive is operated in the mode of operation associated with said same power profile. The mapping of the logical devices to the physical disk drives may be changed in order to group logical devices assigned the same power profile onto the same physical disk drive.

Abstract: Disk drive power states are managed. Information is received for use in determining a desired power state of a disk drive that is not currently being accessed. The disk drive is caused to have a spun up power state before the disk drive is next accessed.

Abstract: A disk drive apparatus has a magnetic platter, a disk drive motor, and a disk drive controller. The disk drive controller is capable of storing data onto and retrieving data from the magnetic platter while the magnetic platter turns at a predefined maximum speed. The disk drive controller is configured to receive a command to access a storage location on the magnetic platter from an external storage controller, and direct the disk drive motor to increase rotational speed of the magnetic platter to the predefined maximum speed in response to the command. The disk drive controller is further configured to, prior to the magnetic platter reaching the predefined maximum speed, access the storage location on the magnetic platter in response to the command. Accordingly, early access to storage locations on the magnetic platter is not substantially hindered by the spin up process.

Abstract: A data storage system having a host computer/server coupled to a bank of disk drives through an interface. The bank of disk drives has a plurality of disk units, each one of such disk drive units having a magnetic storage media. The interface includes: a plurality of front-end directors coupled to the host computer/server; a plurality of back end directors coupled to the disk drive units; and, a global cache memory available for caching user data for the plurality of disk drives. The global cache memory comprises a plurality of non-volatile memory global cache memory sections distributed among disk drive units within the bank of disk drive units. The non-volatile memory global cache memory sections are connected to the back-end directors. Each one of the non-volatile memory global cache memory sections caches user data for the magnetic storage media of the plurality of disk drive units independent of the one of the disk drive units having such one of the non-volatile memory global cache memory sections.

Abstract: A disk drive apparatus has a magnetic platter, a disk drive motor, and a disk drive controller. The disk drive controller is capable of storing data onto and retrieving data from the magnetic platter while the magnetic platter turns at a predefined maximum speed. The disk drive controller is configured to receive a command to access a storage location on the magnetic platter from an external storage controller, and direct the disk drive motor to increase rotational speed of the magnetic platter to the predefined maximum speed in response to the command. The disk drive controller is further configured to, prior to the magnetic platter reaching the predefined maximum speed, access the storage location on the magnetic platter in response to the command. Accordingly, early access to storage locations on the magnetic platter is not substantially hindered by the spin up process.

Abstract: Transferring data from a local storage device to a remote storage device includes providing, to a portion of the local storage device, data to be transferred from the local storage device to the remote storage device using a first mode that accesses an indicator of data being transferred, selecting a second mode for transferring data different from the first mode, where the second mode does not require the indicator, subdividing the portion of the local storage device into chunks, for each of the chunks, transferring the data, and, after all of the data from the chunks has been transferred, using the second mode for transferring data that is provided to the local storage device after selecting the second mode.

Abstract: A PRECOPY command identifies source and destination devices. Data begins to transfer from the source device to the destination device in a background mode under the control of a copy program that transfers the data on a track-by-track basis. Changes to the data tracks are monitored in three lists. The copy program monitors the first two lists to determine when a data track in a source device has been written and needs to be retransferred to the destination device to provide the most up to date data. Procedures assure that any data access to a particular track in either the source by any application prior to the activation of a formal transfer are accommodated to maintain data integrity. An ACTIVATE command makes the destination device available to another application and activates another copy operation. Procedures assure that any data access to a particular track in either of the source or destination devices by any application prior to the transfer of that track are accommodated to maintain data integrity.

Abstract: In a multi-processor system in which several processors compete for exclusive use of a shared resource, a claimant processor asserts exclusive access to a resource by determining whether there exists a competing claim to exclusive access to said resource and then posting a claim to exclusive access to said resource. Following lapse of an interval, the claimant processor then determines whether there exists a competing claim to exclusive access to said resource. Depending on whether or not such a claim exists, the claimant processor then either takes control of the resource or makes another attempt after waiting.

Abstract: A method, system, and computer program product are disclosed for managing data in a cache. A first cache memory is provided that includes data. A second cache memory is provided that also includes data in which at least some of the data in the first cache memory is the same as at least some of the data in the second cache memory. In response to a request for data that is stored in both the first and second cache memories, one of the cache memories is chosen in accordance with an access balancing technique. The access balancing technique may include at least one of selection using round robin, and selection based on statistical analysis such as access frequency of the first and second cache memories. First and second access balancing techniques may be used for data accessed from the cache memories, which may comprise disk data and control data, such as data indicating whether data in the caches has been modified and is write pending.

Abstract: A scheduler for selecting a logical volume for scheduling pending I/O tasks for job generation. The scheduler includes a main scheduler that selects from among multiple sub-schedulers that operate according to different scheduling approaches, e.g., high priority read I/O request scheduling, urgency of non-read I/O tasks, as well as load balancing and round robin schemes. In selecting a sub-scheduler, the main scheduler considers the amount of time allocated to performing read I/O requests, as well as the level of urgency associated with the logical volumes and the disk adapter that manages those logical volumes for non-read I/O tasks.

Abstract: Managing a cache memory includes using a first cache memory, copying data from the first cache memory to a second cache memory, and, following copying, using the second cache memory along with the first cache memory. Prior to using the second cache memory, data may be copied to the second cache memory in response to the data being provided from a disk storage area to the first cache memory. Copying data may include background copying the data during times when the cache memories are not otherwise being used. Using the second cache memory along with the first cache memory may include providing data from a disk storage area to a first cache memory, providing data from the disk storage area to a second cache memory, where the first and second cache memories contain at least some data that is different, and writing a portion of the data to both of the cache memories in response to the portion of data being modified while stored in the cache memories.