Sandisk Technologies Inc.

Robert George Young

Sergey Anatolievich Gorobets

Alan David Bennett

Neil David Hutchison

Liam Michael Parker

Neil Richard Darragh

To make more efficient use of storage capacity, a non-volatile storage system will store system data on marginal word lines. In one embodiment, a marginal word line is a word line that is not suitable to store host data because it is not sufficiently reliable for properly programming and reading the host data.

Nonvolatile memory system storing system data in marginal word lines

A non-volatile memory system includes a memory section having a non-volatile cache portion storing data in a binary format, a primary user data storage section that stores user data in multi-state format, and an update memory area where the memory system stores data updating user data previously stored in the primary user data. The memory system allows a maximum number of blocks for use in the update memory area. When the memory system receives updated data corresponding to user data already written into the primary user data storage section, it determines whether a block of memory is available in the update memory area. In response to determining that a block of memory is not available in the update memory area, the system determines a block of the update memory to remove from the update memory; copies the data content of the determined update block into the cache portion of the memory section; and subsequently writes the updated data into the update memory.

Non-volatile memory system allowing reverse eviction of data updates to non-volatile binary cache

A non-volatile memory organized into flash erasable blocks sorts units of data according to a temperature assigned to each unit of data, where a higher temperature indicates a higher probability that the unit of data will suffer subsequent rewrites due to garbage collection operations. The units of data either come from a host write or from a relocation operation. Among the units more likely to suffer subsequent rewrites, a smaller subset of data super-hot is determined. These super-hot data are then maintained in a dedicated portion of the memory, such as a resident binary zone in a memory system with both binary and MLC portions.

Tracking and handling of super-hot data in non-volatile memory systems

A non-volatile memory system writes logical to physical conversion data to the same memory blocks as user data, and as part of the same page as a segment of user data, as data segments are received and written. When a data block is subsequently compacted and obsolete data removed, the user data from the block is written to a one block and some or all of the logical to physical conversion data from the block is written to another block dedicated for the storage of such logical to physical mapping data.

Techniques of maintaining logical to physical mapping information in non-volatile memory systems

Techniques are presented for performing maintenance operations, such as garbage collection, on non-volatile memory systems will still respecting the maximum latency, or time-out, requirements of a protocol. A safety guard band in the space available for storing host data, control data, or both, is provided. If, on an access of the memory, it is determined that the guard band space is exceeded, the system uses a recovery back to the base state by triggering and prioritizing clean-up operations to re-establish all safety guard bands without breaking the timing requirements. To respect these timing requirements, the operations are split into portions and done in a phased manner during allowed latency periods.

Growing community of inventors

Edinburgh, United Kingdom

Robert George Young