Data protection for write abort
View Patent ↗A portion of a nonvolatile memory array that is likely to contain, partially programmed data may be identified from a high sensitivity read, by applying stricter than usual ECC requirements, or using pointers to programmed sectors. The last programmed data may be treated as likely to be partially programmed data. Data in the identified portion may be copied to another location, or left where it is with an indicator to prohibit further programming to the same cells. To avoid compromising previously stored data during subsequent programming, previously stored data may be backed up. Backing up may be done selectively, for example, only for nonsequential data, or only when the previously stored data contains an earlier version of data being programmed. If a backup copy already exists, another backup copy is not created. Sequential commands are treated as a single command if received within a predetermined time period.
1. A method of selectively protecting data stored in a nonvolatile memory array comprising:
determining whether writing of an addressable unit of data having a first logical address to the nonvolatile memory array would endanger previously stored data in the nonvolatile memory array if the first addressable unit of data was stored in a first location;
if the writing would endanger the previously stored data, then further determining if the endangered previously stored data contains, or is likely to contain, an earlier copy of the addressable unit of data having the first logical address; and
selecting a data protection scheme for protecting the endangered previously stored data according to the further determination.
2. The method of claim 1 wherein the further determining includes determining if there is an addressable unit of data having the first logical address in the endangered previously stored data.
3. The method of claim 1 wherein the further determining includes determining whether the endangered previously stored data and the addressable unit of data are part of a sequential pattern of writing.
4. The method of claim 3 wherein a sequential pattern of writing is defined as a plurality of sequential addressable data packets written in response to a single write command or a plurality of sequential addressable data packets written in response to two or more write commands that are received within a predetermined time as established by a timer.
5. The method of claim 1 wherein a first data protection scheme is selected if the endangered previously stored data contains, or is likely to contain, an earlier copy of the addressable unit of data, the first data protection scheme including copying the earlier copy of the addressable unit of data to another location prior to writing the addressable unit of data.
6. The method of claim 1 wherein the data protection scheme includes copying a portion of the endangered previously stored data that contains, or is likely to contain, an earlier copy of the addressable unit of data only if another copy of the portion is not stored in the nonvolatile memory array.
7. The method of claim 3 wherein the further determining additionally includes, if it is determined that the endangered previously stored data and the addressable unit of data are not part of a sequential pattern of writing then examining the endangered previously stored data for an addressable unit of data having the first logical address.
8. A method of selectively protecting data stored in a nonvolatile memory array comprising:
determining whether writing of an addressable unit of data having a first logical address to the nonvolatile memory array would endanger previously stored data in the nonvolatile memory array if the first addressable unit of data was stored in a first location;
if the writing would endanger the previously stored data, then further determining if the endangered previously stored data contains an addressable unit of data with a logical address that matches the first logical address; and
selecting a data protection scheme for protecting the endangered previously stored data according to the further determination.
9. The method of claim 8 wherein the first location is an upper page, the endangered previously stored data includes lower page data and the further determining includes examining the lower page data to see if it contains an addressable unit of data with a logical address that matches the first logical address.
10. A nonvolatile memory system comprising:
a nonvolatile memory array; and
a memory controller configured to:
determine whether writing of an addressable unit of data having a first logical address to the nonvolatile memory array would endanger previously stored data in the nonvolatile memory array if the first addressable unit of data was stored in a first location;
if the writing would endanger the previously stored data, then further determine if the endangered previously stored data contains an addressable unit of data with a logical address that matches the first logical address; and
select a data protection scheme for protecting the endangered previously stored data according to the further determination.
11. The nonvolatile memory system of claim 10 wherein the nonvolatile memory array is a multilevel cell array.
12. The nonvolatile memory system of claim 10 wherein the nonvolatile memory system is embodied in a removable memory card.