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Method and Apparatus for Memory Mirroring in Servers With Nonvolatile Memory

IP.com Disclosure Number: IPCOM000239579D
Publication Date: 2014-Nov-17
Document File: 2 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method in the area of server memory subsystem to store data in DRAM memory and mirror data in nonvolatile memory

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Method and Apparatus for Memory Mirroring in Servers With Nonvolatile Memory

Mirroring of data is an excellent feature to improve data availability in computer systems. However, this feature has the penalty of reducing available physical memory by half. In the context of server memory architecture, other options are constantly explored to provide mirroring without additional penalty on the memory interface between the controller and DIMMs.

Nonvolatile (NV) memory is one such potential option to consider for use; however, the operating speeds, capacity/densities, and the interface are not a perfect match compared to volatile memory.

A memory controller having M number of channels for main memory (DRAM) and N number of channels for NV memory, where the N channels would be used mainly for storing mirrored data.

Memory controller with an infrastructure to support the above function during mainline traffic comprising, a "mirror address table" to track what address needs mirroring on N channels and a "mirror scrub engine" to read one or more address range from M channel(s) and copy to N channel(s).

Mirror scrub engine further has an internal buffer to hold a copy of the main write sent to M channels, until they are written to the memory behind N channels. This buffer can be circular to create space for written data on N channels and, therefore, can accommodate newer writes in the freed up space.

Buffer size can be chosen to enable smooth data flow (without overflow) considering,

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