Abstract: Provided are a method, system, and article of manufacture, wherein a request is received for switching a logical volume from one state to another state, wherein the logical volume is in a mirrored state if data corresponding to the logical volume is mirrored from a first storage to a second storage, and wherein the logical volume is in a non-mirrored state if the data corresponding to the logical volume is not mirrored from the first storage to the second storage. A determination is made as to whether to perform the switching, in response to receiving the request.

Abstract: A method and system presents a plurality of selections to a user for updating a system configuration from the choices of: an immediate mode, a scheduled queued mode, a queued mode, and an optimized activation mode. The immediate mode activates all change requests immediately. The scheduled queued mode queues all change requests and activates the change requests at a predetermined time. The queued mode queues all change requests and activates the change requests after receiving a triggering event. The optimized activation mode analyzes the system usage to determine and optimally vary the mode among the immediate mode, the scheduled queued mode, and the queued mode.

Abstract: A method and system presents a plurality of selections to a user for updating a system configuration from the choices of: an immediate mode, a scheduled queued mode, a queued mode, and an optimized activation mode. The immediate mode activates all change requests immediately. The scheduled queued mode queues all change requests and activates the change requests at a predetermined time. The queued mode queues all change requests and activates the change requests after receiving a triggering event. The optimized activation mode analyzes the system usage to determine and optimally vary the mode among the immediate mode, the scheduled queued mode, and the queued mode.

Abstract: A method and system for storing data in a redundant array of inexpensive disks (RAID) data storage subsystem is disclosed. The RAID data storage subsystem includes a plurality of drives. The method and system include temporarily storing data in a first portion of the plurality of drives using a first RAID level and relatively permanently storing the data in a second portion the plurality of drives using a second RAID level. The step of relatively permanently storing the data is performed at a time when performance of the system is not substantially affected by storage using the second RAID level. Furthermore, the temporary storing step and the step of storing the data using the second RAID level may be performed throughout operation of the RAID data storage subsystem. Thus, RAID data may be cached using the first RAID level, then relatively permanently stored using the second RAID level.

Abstract: A method and system in data processing system are disclosed for the dynamic scheduling of a plurality of requests to access a disk. Each of the requests is associated with a location on the said disk which each of the requests is attempting to access. A scan queue is established for storing the plurality of requests. The plurality of requests are processed in a sequential order. The sequential order is determined utilizing the location on the disk being accessed by each of the requests. Upon one of the stored requests being urgent, the urgent request is processed. The urgent request is associated with a first location on said disk. Processing of the requests then continues in a second sequential order. The second sequential order is determined utilizing the first location. The next request to be processed is one of the requests which is associated with a physically closest location on the disk.

Abstract: A method and system for a data storage system to update stored data with received data in a cache associated with the data storage system where the data storage system comprises N data storage drives is provided, where data and calculated parity are striped across the N data storage drives. An associated cache is provided with the data storage system for receiving data. The data in the cache is periodically examined to determine if the data includes all sequential data contained within a complete stripe within the data storage system. Data is fetched from the N data storage drives into the cache and the parity for the stripe is calculated by logically combining the received data in the cache and fetched data from the data storage drives if the cache is determined not to include all sequential data contained within the complete stripe.

Abstract: Means and method are disclosed for managing data while a RAID system is recovering from a media error. As a media error occurs, the failing storage device is identified and the areas of failure are recorded in non-volatile storage. A data recovery process is then continued so that a maximum amount of data can be recovered even though more than one error has occurred. Areas of failure are recorded in both non-volatile memory on the RAID adapter card and also in reserved areas of remaining storage devices. The storage areas that have been detected to contain media errors are stripe number, stripe unit number and also down to the sector number level of granularity. When the user tries to access data, these records are checked. If there is an entry in the table for a stripe being accessed, the user will receive an error message. Although the user may lose a small portion of the data, the user is only presented with an error message instead of incorrect data. The table can also be checked on write operations.

Abstract: A method for migrating data from one level of RAID system to the same or another level of RAID system having the same or a different number of removable and identifiable storage devices and having the same or a different stripe unit size is disclosed. The storage devices can be attached to the system at a number of different attachment points which facilitates replacement or removal of a failed device. The system is represented as a logical media drive. After determining the number of migrations and the direction of migration, a start logical block address and an end logical block address is defined. The migration is performed by moving data from the source physical blocks to the destination physical blocks starting with the physical block corresponding to the start logical block address and continuing to the physical block corresponding to the end logical block address.

Abstract: The method and system for improved efficiency and parity calculation in RAID data storage system. RAID data storage systems permit recovery of data in the event of a drive failure by storing a parity value for each stripe of data on a separate drive. Each time data is written to a RAID data storage the parity value for the associated data stripe must be updated. Parity may be calculated utilizing two different algorithms. New parity may be calculated utilizing the old data value, the new data value and the old parity value, or calculated utilizing the new data value and all remaining old data within the associated data stripe. The number of input/output operations required to calculate parity utilizing each algorithm is predetermined and the method requiring the least number of input/output operations is selected, unless data sequentiality is detected.

Abstract: A redundant array of inexpensive disks (RAID) includes a plurality of disk drives organized as a plurality of stripes, wherein each stripe includes a plurality of stripe units. A host processor system sends write commands in write-through mode to a RAID controller, some of which are immediately processed by the controller, and others of which are temporarily stored in a stash. Commands stored in the stash for data writes that only partially fill a stripe may be coalesced with another write command that also only partially fills the same stripe. This coalescing occurs for commands for data writes that span one or more stripes, and that may start or stop in the middle of a stripe, as well as in the middle of a stripe unit. In addition, two different commands for writing data to different stripe units, but from the same stripe, can also be coalesced. The coalescing of write commands in the stash reduces the number of disk I/O's and improves data throughput.

Abstract: Because correct configuration data is essential to the operation of any RAID system, and because multiple copies of the configuration data are kept, not only in the RAID controller itself, but also in each disk drive unit in the configuration, it is imperative that the various copies of the configuration data do not become "out of synchronization", which means that one or more copies of the configuration data are different from one or more other copies of the configuration data. To maintain synchronization of all copies of the configuration data, the current invention compares the configuration data stored in the RAID controllers' NVRAM to that of the current system, and records any new, non-responding, repositioned or unidentified storage devices in a change list.

Abstract: Because correct configuration data is essential to the operation of any RAID system, and because multiple copies of the configuration data are kept, not only in the RAID controller itself, but also in each disk drive unit in the configuration, it is imperative that the various copies of the configuration data do not become "out of synchronization", which means that one or more copies of the configuration data are different from one or more other copies of the configuration data. To maintain synchronization of all copies of the configuration data, the current invention compares the configuration data stored in the RAID controller's NVRAM to that of the current system, and records any new, non-responding, repositioned or unidentified storage devices in a change list.

Abstract: In a data processing system, a redundant array of storage devices is provided for storing data from a host data processing system. When a selected, storage device receives a write command, the selected storage device reads old data from the logical address specified in the write command, and temporarily stores such old data in a buffer. Next, the selected storage device writes new data from the host data processing system to a location specified in the write command. Thereafter, an XOR operation is performed in the selected storage device between the new data and the old data to produce intermediate data. The intermediate data is then transferred to a second storage device within the array. Within the second storage device, old parity data is read from the media in the second storage device and placed in a buffer. Next, an XOR operation is performed in the second storage device between the intermediate data and the old parity data to produce new parity data.