Sun Microsystems, Inc.

Robert Gittins

Swee Boon Lim

Anton Rang

Richard S Brown

Kevin J Clarke

Steve Mcpolin

Sanjay Gurudatt Nadkarni

Devendra R Jaisinghani

In a computer system, a distributed storage system having a data coherency unit for maintaining data coherency across a number of storage devices sharing such data is described. The data coherency unit includes logic to monitor data transition states in each of the data storage devices to detect when the processing status of data being shared by two or more of the storage devices changes. The data coherency unit advantageously ensures a status change in shared data in one storage device is broadcast to other storage devices having copies of the data without having each storage device independently monitor adjourning storage devices to detect data state changes.

Distributed storage cache coherency system and method

One embodiment of the present invention provides a system that facilitates validation of data retrieved from a secondary storage device. The system operates by receiving a write request to write new data to a block of the secondary storage device, and calculating a new checksum value from the new data. The system also retrieves a current checksum value and an old checksum value associated with the block of the secondary storage device. Next, the system performs a checksum write operation to a validation device to update the current checksum value and the old checksum value, and then performs a data write operation to the secondary storage device to write the new data to the block of the secondary storage device.

Method and apparatus for facilitating validation of data retrieved from disk

A system and method are provided for recovering from the failure of a mirrored boot device (e.g., disk drive). One method is implemented for a computer system that mirrors two (or more) boot devices. If one of the devices fails, a set of compensating activities is performed, which may include removing the failed device from the list of devices from which the system may boot, deleting mirror state data from the device and removing the failed device from the mirroring scheme. After the failed device is repaired or replaced, a set of reintegrating activities is performed, which may include including the device in the mirroring scheme, restoring mirror state data to the device and adding the device to the list of boot devices. Even if the system includes only two mirrored boot devices and one of them fails, it can continue operation and can reboot successfully without using stale data.

Method and apparatus for recovering from failure of a mirrored boot device

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Westminster, CO, United States of America

Robert Gittins