Electrical computers and digital processing systems: memory – Storage accessing and control – Hierarchical memories
Reexamination Certificate
2005-09-27
2005-09-27
Kim, Hong (Department: 2186)
Electrical computers and digital processing systems: memory
Storage accessing and control
Hierarchical memories
C711S145000, C711S120000, C711S162000, C714S006130, C714S013000
Reexamination Certificate
active
06950907
ABSTRACT:
A dirty memory subsystem includes storage operable to store redundant copies of dirty indicators. Each dirty indicator is associated with a respective block of main memory and is settable to a predetermined state to indicate that the block of main memory associated therewith has been dirtied. By providing redundant storage for the dirty indicators, any difference between the stored copies of the dirty indicators can be considered as indicative of memory corruption, for example as a result of a cosmic ray impact. As the different copies can be stored in different locations, it is unlikely that a cosmic ray impact would affect all copies equally. If a difference between the stored copies is detected, then the dirty indicator can be take as being unreliable and remedial action can be taken. For example, it can be assumed that a block of main memory has been dirtied if any of the copies of the dirty indicator has the predetermined state. Such a memory finds application in a method of managing reinstatement of an equivalent memory state in the main memory of a plurality of processing sets of a fault tolerant computer following a lock step error.
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UK Combined Search and Examination Report, application No. GB0029103.9, filed Nov. 29, 2000.
Garnett Paul Jeffrey
Harris Jeremy Graham
Kim Hong
Kivlin B. Noäl
Meyertons Hood Kivlin Kowert & Goetzel P.C.
Sun Microsystems Inc.
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