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:
Sep. 16, 2003
Filed:
Jun. 30, 2000
Jack Justin Stiffler, Marion, MA (US);
Donald Burn, Westborough, MA (US);
Other;
Abstract
System-directed checkpointing is accomplished following each checkpoint by mapping all memory pages, including read-only pages and read/write pages as read-only pages. Therefore, when an attempt is made to write to a page, a page-fault interrupt is generated. If the page is a read-only page, then normal page-fault interrupt protocol is followed. If the page is a read/write page that has temporarily been labeled read-only, the page is copied to a buffer and the memory map is changed to indicate that the page is now a read/write page. The pages in the buffer can then be used to restore the system after a fault. In accordance with another embodiment of the invention, after the aforementioned system interrupt occurs, the identity of the page is recorded in a backup computer, but the page itself is not copied. In addition, the locations of all pages modified through I/O events are also recorded. At the time of a checkpoint, the checkpoint software copies the contents of all modified pages to a memory in the backup computer. The backup computer can then be used to restart the system after a fault. This latter technique can also be used in a clustered environment with one computer effectively serving as a backup for every other computer in the cluster.