Abstract: Improved host I/O performance and availability of a storage array during rebuild is obtained by prioritizing I/O requests. In one embodiment, rebuild I/O requests are given priority over host I/O requests when the storage array is close to permanently losing data (for example, failure of one more particular disk in the storage array would result in data loss). Rebuild I/O requests continue to have priority over host I/O requests until the storage array is no longer close to permanently losing data, at which point host I/O requests are given priority over rebuild I/O requests.

Abstract: A storage device is configured with one or more processes that receive, process, and pass on jobs from a source. The number of jobs received by a process is compared with the number of jobs completed and/or passed on by the process. If the number of jobs that are received is disproportionate to the number of jobs completed and/or passed on by the process, a hang may exist and a corrective action, such as resetting, may be performed along with a request for all or some of the jobs to be resent.

Abstract: Multiple storage devices are monitored to detect failure of a storage device. Upon detection of a storage device failure, a determination is made regarding whether a first data reconstruction technique is available. If a first data reconstruction technique is available, the data is reconstructed from the failed storage device using the first data reconstruction technique. If the first data construction technique is not available, the data is reconstructed from the failed storage device using a second data reconstruction technique.

Abstract: Multiple storage devices are monitored to detect failure of a storage device. Upon detection of a storage device failure, a determination is made regarding whether a first data reconstruction technique is available. If a first data reconstruction technique is available, the data is reconstructed from the failed storage device using the first data reconstruction technique. If the first data construction technique is not available, the data is reconstructed from the failed storage device using a second data reconstruction technique.

Abstract: A block of data is written to a location on a first storage system. Version checking data associated with the block of data and having a predetermined initial value is also written to the first storage system. The version checking data is then written to a second storage system. Upon subsequent writing of data to the same location on the first storage system, the version checking data on the first storage system is incremented and the incremented version checking data is stored on the second storage system. When reading the group of data from the first storage system, the data is validated by comparing the version checking data on the first storage system with version checking data on the second storage system.

Abstract: Improved host I/O performance and availability of a storage array during rebuild is obtained by prioritizing I/O requests. In one embodiment, rebuild I/O requests are given priority over host I/O requests when the storage array is close to permanently losing data (for example, failure of one more particular disk in the storage array would result in data loss). Rebuild I/O requests continue to have priority over host I/O requests until the storage array is no longer close to permanently losing data, at which point host I/O requests are given priority over rebuild I/O requests.

Abstract: Improved host I/O performance and availability of a storage array during rebuild is obtained by prioritizing I/O requests. In one embodiment, rebuild I/O requests are given priority over host I/O requests when the storage array is close to permanently losing data (for example, failure of one more particular disk in the storage array would result in data loss). Rebuild I/O requests continue to have priority over host I/O requests until the storage array is no longer close to permanently losing data, at which point host I/O requests are given priority over rebuild I/O requests.

Abstract: A method of managing data in a hierarchical data storage system employing data redundancy schemes includes prioritizing a data rebuild based on a most vulnerable data redundancy scheme in the storage system. A data storage system embodying this rebuild prioritization method is also described. Prioritizing the data rebuild includes enabling a rebuild of the most vulnerable data redundancy scheme prior to enabling a rebuild of any other data redundancy scheme in the system. The most vulnerable data redundancy scheme is determined by comparing a probability of losing data that can be prevented by a rebuild for each data redundancy scheme with respect to the potential for one or more next storage device failures in the data storage system.