Abstract: A method for scanning a mass-storage device in communication with a global memory includes allocating a scan buffer in the global memory for placement of information descriptive of any errors found during the scan. When a scanning utility identifies a data error on the mass-storage device, it writes structured information descriptive of the error to the scan buffer. This information is available to an error-correction utility. The error-correction utility uses this information to determine, with a minimum of human intervention, which data errors to repair and which to ignore.

Abstract: A method for scanning a disk to verify the integrity of data records stored on the disk includes comparing copies of meta-data derived from a data record to be verified. For each data record, a first copy of the meta-data for that record is stored in a cache memory and a second copy of the meta-data for that record is stored on the disk. To verify a data record, a third copy of the meta-data is made by copying the second copy to the cache-memory element. The first and third copy are then compared to verify the integrity of the data record. By reducing the number of disk accesses and eliminating the need to access the data record itself, the scanning method enables a disk to be scanned rapidly.

Abstract: The meta-data pattern for records in an orphan track is not readily compressible into a form suitable for maintaining in memory. A method is provided for periodically attempting to compress meta-data from orphan tracks as newly compressible meta-data patterns are made available. The method includes specifying a compressed representation for a first meta-data pattern and determining a second meta-data pattern formed by the meta-data associated with the orphan track. If the second meta-data pattern is consistent with the first meta-data pattern, a compressed representation of the second meta-data pattern is generated and maintained in memory. In an optional feature, meta-data that could not be compressed is collected and periodically transmitted to a data-analysis node for analysis.

Abstract: A method of dynamically changing a storage system from a RAID configuration to a mirror configuration is provided. The change occurs when a device begins to fail or fails completely. Data from the logical volumes of the failed device is written to corresponding parity volumes within the RAID group. In addition, data from all logical data volumes is copied to spare devices. Once all the data is copied, the system operates in a mirrored mode. A mirrored mode includes writing data to both and active and backup volume for each write transaction. When the failed device is replaced the data and parity volumes are restored. Once restored, the spare devices are returned to inactive status.

Abstract: A method and appartus maintain a disk drive system in a more reliable and simplified manner. Maintenance commands directed to logical volumes of the physical disk drive units are configured to apply to the entire physical disk drive unit so that a maintenance command need not be repeated for each logical volume to be affected. Should a failure be received with regard to any one or more logical volumes, the apparatus and method repeat the maintenance command, but only for those failed logical volumes. The maintenance command can also be applied to a group of physical devices using this procedure.

Abstract: A method and apparatus provide for maintenance and on-line scanning of the mass storage elements of a computer system without taking those elements off-line. Maintenance commands are sent to the disk drive elements during those time intervals when they are less busy with commands from the host computer(s). In a special instance, a SCSI code load update command can be implemented and forwarded to one or more disk drives connected over a SCSI bus to a disk drive controller. The disk drive controller returns busy signals to any incoming read operations. In a particular instance where there are mirrored drives, read operations can be redirected to a mirrored drive which is not being updated. The host computer system provides substantially no change in throughput performance as the maintenance operations occur.