摘要:
A method and system for improving data migration from source data stripes to destination stripes in a Redundant Array of Independent Drives (RAID) logical drive migration (LDM). The invention describes a procedure for checkpointing data migrations, so that if the system should fail in the middle of the LDM, the computer can resume the LDM from the last checkpointed destination stripes, thus ensuring accurate tracking of data location. Further, the invention also provides the capability of properly checkpointing a data write to a stripe according to whether or not the stripe unit has been migrated previously.
摘要:
A method and system for accessing data in a redundant array of inexpensive disks (RAID) subsystem is disclosed. The RAID subsystem includes a RAID controller having a cache and a plurality of disks. The method and system include utilizing the cache in a write back mode if the RAID subsystem is lightly loaded. In write back mode, the data is written to the cache prior to storing the data on at least one disk of the plurality of disks or prior to outputting the data from the RAID subsystem. The method and system also include utilizing the cache in a write through mode if the RAID subsystem is heavily loaded. In the write through mode, the data is written directly to at least one disk of the plurality of disks and, in a preferred embodiment, at the same time written to any cache buffer. Thus, data is written to the disks without the delay associated with managing a full cache when in write back mode required to flush an existing cache buffer to make a free buffer available.
摘要:
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.
摘要:
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. Alternatively, the parity for the stripe is calculated by logically combining only data within the cache for the stripe, if data in the cache is determined to include all sequential data contained within a complete stripe, thereby minimizing the number of input/output operations required to update data.
摘要:
A method, system and computer program product for updating firmware in a disk in a disk array in a RAID storage system without deactivating a server coupled to the disk array. Upon selecting the disk whose firmware is to be updated, the selected disk may enter a degrade mode of operation where a RAID controller coupled to the RAID storage system may prevent requests from reaching the selected disk thereby suppressing activity on the selected disk to allow the firmware to be updated. During the updating of the firmware, any stripes updated may be tracked. Upon completion of the firmware update, the stripe units in the selected disk associated with the stripes updated may be rebuilt. In this manner, firmware may be updated on a disk in a RAID storage system without deactivating the server thereby allowing the server to continuously stay active.
摘要:
A redundant disk array and improved method for redundant disk array access improve the performance of storage systems for computers. The disk array and method retrieve data from redundant drives according to an algorithm that will fetch contiguous pages from a single storage device, rather than alternating accesses between storage devices. The result is a reduced access time and increased data throughput.
摘要:
A method and system for updating stored data with received data in a cache associated with the data storage system is provided, where the data storage system comprises N data storage drives, where data and calculated parity are striped across N data storage drives, where a stripe comprises multiple data sectors on each of N data storage drives. An associated cache is provided with the data storage system into which data is received. The data in the cache is periodically examined to determine if the cache includes all sequential data sectors contained within a complete stripe within the data storage system. Parity is calculated for the complete stripe by first calculating a range of sectors between which all sectors received into the cache for the complete stripe fall. Next, only those sectors within the range of sectors which are not included in the data in the cache for the complete stripe are read from the N data storage drives into the cache. Finally, the range of sectors in the cache for the complete stripe are logically combined. The parity is calculated such that input/output operations within said data storage system are minimized.
摘要:
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. If sequential data is present the parity value is calculated utilizing the new data and all old data in the associated data stripe, even if a greater number of input/output operations are initially required, as further sequential input/output operations will be more efficient.
摘要:
A method and system in a data storage system for reading stored data from the data storage system, where the data storage system comprises N data storage drives and an associated cache, where data and calculated parity are striped across the N data storage drives, where a stripe comprises multiple sectors on each of the N data storage drives. Data is requested from the data storage system. A determination is made of whether or not the requested data currently resides in a cache associated with the data storage system. In addition, a determination is made of whether or not the requested data sequentially follows other sectors also residing in the cache. Only the requested data is fetched into the cache if it is determined that the requested data does not reside in the cache and the requested data does not sequentially follow sectors in the cache. The requested data and a predefined block of sectors within the N data storage drives are fetched into the cache if it is determined that the requested data does not reside in the cache and the requested data sequentially follows sectors in the cache, where the fetched predetermined block of sectors sequentially follows the requested data.
摘要:
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.