Semiconductor memory device and method for logging monitored events into a buffer

摘要

A semiconductor memory device includes a nonvolatile semiconductor memory in which writing is carried out at a page unit and erasing is carried out at a block unit larger than the page unit, and a controller for transferring data between a host device and the nonvolatile semiconductor memory. The controller includes a log-management section that is configured to: (i) record a page unit of log data in a buffer area each time a monitored event (e.g., error) occurs, the buffer area being partitioned into a plurality of pages and the page unit of log data is recorded in a designated page of the buffer area, and (ii) prior to recording the page unit of log data in the designated page, copy part of the designated page to another page of the buffer area.

主权项

1. A semiconductor memory device, comprising:
a nonvolatile semiconductor memory in which writing is carried out at a page unit and erasing is carried out at a block unit larger than the page unit; and a controller for controlling data transfer between a host device and the nonvolatile semiconductor memory, the controller including a log-management section that is configured to update a log buffer that stores data about monitored events in a plurality of pages of the nonvolatile semiconductor memory and a log data structure that stores addresses of the pages of the nonvolatile semiconductor memory that are part of the log buffer, by performing the steps of: (i) determining an address of a page of the log buffer in which latest log data is stored, the latest log data including a first part and a second part; (ii) reading the latest log data from the page at the determined address and copying the first part of the latest log data into a first page of the nonvolatile semiconductor memory; (iii) updating the first and second parts of the latest log data and storing the updated latest log data in a second page of the nonvolatile semiconductor memory, wherein the first part of the updated latest log data includes data about a latest monitored event and the second part of the updated latest log data includes a log number associated with the latest monitored event; and (iv) updating the log data structure to store addresses of the first and second pages and to identify the second page as storing the latest log data.