Abstract: A system, method, apparatus, and computer-readable medium are provided for expanding the data storage capacity of a virtualized storage system, such as a storage cluster. According to one method, maps are generated and stored that define a stripe pattern for storing data on the storage nodes of a storage cluster. The stripe pattern for each map is defined such that when a storage node is added to a cluster and the data is re-striped according to the new map, only the data that will subsequently reside in the new storage node is moved to the new storage cluster during re-striping. The stripe pattern may be further defined so that during re-striping no movement of data occurs between two storage nodes that existed in the cluster prior to the addition of the new storage node. The stripe pattern may be further defined such that during re-striping an equal amount of data is moved from each of the storage nodes that existed in the cluster prior to the addition of the new storage node to the new storage node.

Abstract: In one embodiment, a switch provides output to a digital radio frequency (RF) modulator having a filtered input stage. The switch is configured to selectively provide a zero power data signal to the RF modulator based on a transient event control signal received at the switch.

Abstract: Techniques for maintaining mirrored storage cluster data consistency on systems with write back cache can employ write-intent logging and periodic log clearing. The techniques can track any outstanding I/Os, data in caches, and data that has gone out of sync between mirrored nodes due to link failures. The techniques can ensure that a power failure on any of the storage nodes does not result in inconsistent data among the storage nodes. The techniques can use gate bitmaps to log outstanding I/Os. The gate bitmaps may be periodically cleared. The clearing period may be selected as to allow enough time for all caches to be flushed and for all synchronizing I/Os to complete. Efficient queuing of I/O requests in conjunction with the efficient operation of multiple gate bitmaps can reduce performance impacts of the gating or logging operations.

Abstract: Methods, systems, and computer program products are provided for making PEI phase implementation independent from DXE phase implementation in a computer system implementing the Extensible Firmware Interface standard. For example, one embodiment of the present invention uses a hand-off block to make SMBASE initialization in PEI independent form SMBASE initialization in DXE. In another embodiment of the present invention, PEI phase is entered in order to resume from an S3 standby state.

Abstract: Technologies are provided herein for asynchronous data replication. A primary server maintains and exposes a storage volume for use by storage clients. The primary server receives write operations directed toward the storage volume and performs the writes on the storage volume. The primary server also creates buckets containing each of the write operations. The buckets are opened at a first point in time and closed at a second point in time that may be selected based upon the contents of the buckets, a predefined time period, or based upon an indication from an application program. The buckets are transmitted to a second server computer asynchronously. When each bucket is received completely by the second server, its contents are written to a storage volume maintained by the second computer. The buckets may be created from pages of a write-back cache utilizing a zero buffer copy mechanism.

Abstract: A method, system, apparatus, and computer-readable medium are provided for improving storage in a disk array are provided. According to aspects of the invention, a redundant disk array is combined with a mechanism for thin provisioning of the array. Thin provisioning refers to a process of allocating physical capacity to logical volumes on an as-needed basis. Data structures containing a mapping between the logical location of stored data and its actual location on a physical device are maintained. Through the use of the thin provisioning mechanism, physical storage space can be allocated sequentially, regardless of the order of logical writes. In this manner, the data stored on the array grows in a linear manner. The data structures maintained by the thin provisioning mechanism can be used to identify the portions of a device or an array that have been previously written.

Abstract: Technologies are presented herein for synchronization of I/O operations in a data storage system. Multiple reader and writer locks may be acquired by calling processes at two different granularities. Locks may be acquired for an area of storage equivalent to the logical unit of allocation or for a sub-provision area equivalent to a unit of snapshot read-modify-write. Each lock may be represented by a lock data structure that represents the same amount of logical address space as the logical unit of allocation. A request that arrives to the lock data structure may be placed in a lock wait queue until the request can be honored. A round robin technique may be utilized to respond to requests for locks so that one lock does not starve out other locks.