Abstract: An enlightened storage target may operate as a conventional storage target device, and may have additional capabilities to manage an initiator-target relationship under a service level agreement or quality of service agreement. An initiator may negotiate a service level agreement with the enlightened target, then the target may manage storage within the target device to meet the service level agreement. The target may also include a monitoring system that may monitor actual performance and compare the performance against the service level agreement. When the service level agreement is not being met, the target may alert the initiator and, in some cases, take precautionary or other actions until the service level agreement is either changed or is met.

Abstract: A storage system may manage a logical unit using a differencing mechanism that captures changes to a base version of the logical unit. The logical unit may be presented to an operating system as a single storage device, while the logical unit may actually be provided by several storage devices that operate in conjunction with each other. In some cases, a single base version of the logical unit may be used to simultaneously provide multiple logical units, each of the logical units having a separate and independent differencing portion. In one such embodiment, a common base extent may contain read only versions of file blocks while each logical unit may contain independent differencing extents that contain changes to the base extent.

Abstract: A storage system with a duplicate network storage device may change to and from a synchronous to asynchronous write connection based on a service level agreement. Degradation of a network connection or device performance may cause synchronous writes to be changed to asynchronous network writes, and synchronous writes may be performed on a second device. During the asynchronous operation, a differencing set may be created on a local storage device and used to update the network storage device. When the network storage device becomes able to meet the service level agreement with synchronous writes, the system may include the network storage device for synchronous writes.

Abstract: A remotely managed storage system may configure logical units using a low level storage controller on each managed computer system plus a target driver for each shared storage device. The storage controller may present logical units to operating systems running on a computer system and may operate on a lower level than a host operating system or hypervisor. A target driver may allow remote devices to use the local storage devices for other logical units. A storage master may configure the various components across a group of computers to create logical units of storage that are backed by multiple storage devices.

Abstract: A storage management system may monitor file activity from a file system and tag storage blocks with metadata. The metadata may be used by the storage management system to apply various policies to the blocks. The tagging operation may intercept or monitor file system interaction to classify storage blocks as operating system, application, and data files, as well as other classifications. Some embodiments may include file types, restrictions for physical location, access frequency, block size, and other metadata. The tags may be appended to storage blocks, stored in a separate database, or otherwise associated with the storage blocks. A storage management system may manage storage over many computing devices by handling the storage blocks according to the metadata tags.

Abstract: A file system may access a logical unit by addressing storage space using a constant block size, but the underlying logical unit may physically store information using different block sizes for different types of files. Certain file types may be stored using large blocks sizes for performance, while other file types may be stored using smaller block sizes for storage efficiency. A storage management system may create the logical unit from different block extents on various storage devices, where each block extent may be created with different block sizes. The system may place a file in a block extent that may be appropriate for the file type, and may perform a translation between the file system's request for a specific block and the manner in which the block is stored on the media.

Abstract: A storage management system may create a logical storage unit from blocks of storage provided from multiple storage devices. The storage management system may operate using a service level agreement that defines a preferred or minimum performance standard for accesses to the logical storage unit. The service level agreement may include minimum replications, system performance, and system operation characteristics. As read and write operations are performed against the logical storage unit, the configuration of the logical storage unit may be changed to meet the service level agreement. The storage management system may assess and map the capabilities of all available storage devices for a system, then provision a logical storage unit that may initially meet the target service level agreement. When system performance does not meet the service level agreement, read operations may be striped, alternative storage devices may be used, or the location of replicated blocks may be changed.