The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 10, 2009
Filed:
Aug. 31, 2004
Chao Zhang, Milpitas, CA (US);
Robert Tower Frey, Milpitas, CA (US);
Chao Zhang, Milpitas, CA (US);
Robert Tower Frey, Milpitas, CA (US);
EMC Corporation, Hopkinton, MA (US);
Abstract
Systems and methods can provide mirrored virtual targets and online synchronization and verification of the targets while avoiding deadlock, inconsistencies between members of the target, and false verification failures. A lock within the storage switch can limit the number of outstanding commands for a physical target to one during synchronization and verification operations. In one embodiment, a lock can be implemented as one or more resource tables maintaining an indication of the number of transfer ready signals available from physical targets. During typical write operations, deadlock can be avoided by determining whether each physical target for the mirrored operation can issue a transfer ready signal prior to issuing a command to the physical target. When a synchronization or verification operation begins, the maximum available number of transfer ready signals for each target can be decremented to one in order to limit the total number of outstanding commands for each target to one.