System and method for recovering a directory for a log structure

Details System and method for recovering a directory for a log structure System and method for recovering a directory for a log structure

1998-05-15

2000-04-18

Moise, Emmanuel L.

Error detection/correction and fault detection/recovery

Data processing system error or fault handling

Reliability and availability

714 20, 711114, 711136, G06F 1100, G06F 1200

Patent

active

060527994

ABSTRACT:
In a storage system comprising an array of storage devices including a processor and memory, a plurality of data blocks are organized on the storage devices in segments striped across the storage devices. A main directory stored in memory contains the location on the storage device of each of the current data blocks. A method is provided for recovering a main directory in the event that the main directory becomes damaged. A segment directory having information on the data blocks in the segment is stored as part of the segment on the storage devices. Periodically a checkpoint of the main directory is written to the storage devices. A list is maintained of closed segments written to the storage devices since the checkpoint directory was written to the storage devices. During a main directory recovery procedure, the checkpoint of the main directory is read into memory, and for each segment that is indicated by the closed segments list as having been closed since the checkpoint of the main directory was written to the disk, the information in the corresponding segment directory is used to update the checkpoint directory.

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