Memory controller-independent memory mirroring

1. A method of memory controller-independent memory mirroring in an information handling system (IHS), comprising:

providing a mirroring association between a first memory segment and a second memory segment that are located in a system memory and that are coupled to a memory buffer, wherein the mirroring association is independent of a memory controller that is associated with the system memory and the second memory segment is unknown to the memory controller;

receiving, by the memory buffer from the memory controller, write data that is directed to a first memory location in the first memory segment;

writing, independent of the memory controller with the memory buffer, the write data to both the first memory segment and the second memory segment according to the mirroring association such that the first memory segment includes primary write data and the second memory segment includes mirrored write data that is a copy of the primary write data;

receiving, by the memory buffer from the memory controller, a plurality of read commands directed to the first memory location in the first memory segment, and, in response:

retrieving read data by reading the write data from an alternating one of the first memory segment and the second memory segment in response to the plurality of read commands; and

storing the read data in the memory buffer such that the memory buffer includes both first read data that is the primary write data that was read from the first memory segment in response to the plurality of read commands and second read data that is the mirrored write data that was read from the second memory segment in response to the plurality of read commands; and

performing, by the memory controller without knowledge of the mirroring association between the first memory segment and the second memory segment, a patrol scrubbing process using the first read data and the second read data in the memory buffer such that each of a plurality of addresses in both the first memory segment and the second memory segment are subject to the patrol scrubbing process over the plurality of read commands, wherein a patrol scrub rate is set in the memory controller such that each of the plurality of addresses in both the first memory segment and the second memory segment are subject to the patrol scrubbing process over the plurality of read commands within a predetermined amount of time.

2. The method of claim 1 , further comprising:

utilizing the first read data and the second read data in the memory buffer to determine the cause of a system exception associated with one of the plurality of read commands.

3. The method of claim 2 , further comprising:

storing, in the memory buffer, information identifying which of the first memory segment and the second memory segment was read from last and alternating between the first memory segment and the second memory segment based on the information; and

utilizing the information to determine the cause of the system exception.

4. The method of claim 2 , wherein the utilizing the first read data and the second read data includes determining whether one of the first read data and the second read data includes a miscompare.

5. The method of claim 2 , wherein the utilizing the first read data and second read data includes determining whether the system exception was due to one of a channel transmission error and a write error.

6. The method of claim 1 , further including:

comparing, with the memory buffer, the first read data and the second read data; and

in response to determining that the first read data and the second read data do not match, storing the first read data and the second read data in the memory buffer until the first read data and the second read data are used to determine the cause of a system exception associated with one of the plurality of read commands.

7. The method of claim 1 , further comprising:

receiving, by the memory buffer, memory mirroring configuration information that is used to provide the mirroring association.

8. A method of memory controller-independent memory mirroring in an information handling system (IHS), comprising:

receiving, by a memory buffer, memory mirroring configuration information from a management module;

providing, by the memory buffer, a memory mirroring association between a primary memory segment and a secondary memory segment using the memory mirroring configuration information, wherein the memory mirroring association is independent of a memory controller and the second memory segment is unknown to the memory controller;

receiving, by the memory buffer, write commands and write data from the memory controller, wherein the write commands are directed toward addresses in the primary memory segment;

writing the write data to both addresses in the primary memory segment and to addresses in the secondary memory segment independent of the memory controller using the memory buffer such that the primary memory segment includes primary write data at the addresses in the primary memory segment and the secondary memory segment includes mirrored write data at the addresses in the secondary memory segment that is a copy of the primary write data;

receiving, by the memory buffer, a first read command from the memory controller, the first read command being directed toward the addresses in the primary memory segment;

selecting, by the memory buffer in response to the first read command, one of the primary memory segment and the secondary memory segment from which to read the write data according to the first read command, wherein the selecting is independent of the memory controller;

retrieving, by the memory buffer based on the selecting in response to the first read command, first read data that is one of (1) the primary write data from the addresses in the primary memory segment or (2) the secondary write data from the addresses in the secondary memory segment;

caching the first read data in the memory buffer and storing tracking information identifying the selected one of the primary memory segment and the secondary memory segment;

receiving, by the memory buffer, a plurality of subsequent read commands from the memory controller, the plurality of subsequent read commands being directed toward the addresses in the primary memory segment;

selecting, by the memory buffer in response to the plurality of subsequent read commands and using the stored tracking information, the one of the primary memory segment and the secondary memory segment that was not selected according to a previous read command;

retrieving, by the memory buffer based on the selecting in response to the second read command, either the first read data that is the primary write data from the addresses in the primary memory segment, or second read data that is the secondary write data from the addresses in the secondary memory segment that were not selected according to the previous read command;

comparing, by the memory buffer, the first read data and the second read data;

in response to determining that the first read data and the second read data do not match, holding the first read data and the second read data in the memory buffer until the management module can analyze the first read data and the second read data; and

performing, by the memory controller without knowledge of the mirroring association between the first memory segment and the second memory segment, a patrol scrubbing process using the first read data and the second read data in the memory buffer such that each of the addresses in both the first memory segment and the second memory segment are subject to the patrol scrubbing process over the first read command and the plurality of subsequent read commands, wherein a patrol scrub rate is set in the memory controller such that each of the addresses in both the first memory segment and the second memory segment are subject to the patrol scrubbing process over the plurality of read commands within a predetermined amount of time.

9. The method of claim 8 , further comprising:

maintaining, in the memory buffer, a list of addresses in the primary memory segment to which read commands from the memory controller have been directed, wherein the maintaining includes storing tracking information identifying which of the first memory segment and the second memory segment was read from last for each address in the list of addresses.

10. The method of claim 9 , wherein the list of addresses is a first-in-first-out list containing, at any given time, at least a number of addresses equal to the total number of outstanding read commands issued by the memory controller at the given time.

11. The method of claim 8 , further comprising:

receiving a subsequent write command from the memory controller, the subsequent write command being directed toward the addresses in the primary memory segment; and

in response to receiving the subsequent write command, deleting the first read data and the second read data and the tracking information from the memory buffer.

12. The method of claim 8 , wherein the primary memory segment and the secondary memory segment are each one of a rank, a bank, a DRAM chip, a DIMM, and an address range of memory locations.

13. An information handling system (IHS), comprising:

a system memory having a plurality of memory segments;

a memory controller that is coupled to the system memory and that is configured to store data in and retrieve data from the plurality of memory segments;

a memory buffer coupled between the memory controller and the plurality of memory segments, wherein the memory buffer is configured to maintain a mirroring association between a first memory segment and a second memory segment in the plurality of memory segments, wherein the mirroring association is independent of the memory controller and the second memory segment is unknown to the memory controller; and

a management module coupled to the system memory, the memory buffer, and the memory controller, wherein the management module is configured to transmit mirroring association configuration information to the memory buffer;

wherein the memory buffer is further configured to:

receive write data from the memory controller that is directed to memory locations in the first memory segment;

write the write data to both the memory locations in the first memory segment and to memory locations in the second memory segment according to the mirroring association such that the first memory segment includes primary write data and the second memory segment includes mirrored write data that is a copy of the primary write data;

receive a plurality of read commands directed to the memory locations in the first memory segment from the memory controller, and, in response to the plurality of read commands:

retrieve read data by reading the write data from an alternating one of the first memory segment and the second memory segment in response to the plurality of read commands; and

store the read data in the memory buffer such that the memory buffer includes both first read data that is the primary write data that was read from the first memory segment and second read data that is the mirrored write data that was read from the second memory segment; and

wherein the memory controller is configured, without knowledge of the mirroring association between the first memory segment and the second memory segment, to perform a patrol scrubbing process using the first read data and the second read data in the memory buffer such that each of a plurality of addresses in both the first memory segment and the second memory segment are subject to the patrol scrubbing process over the plurality of read commands, and wherein a patrol scrub rate is set in the memory controller such that each of the addresses in both the first memory segment and the second memory segment are subject to the patrol scrubbing process over the plurality of read commands within a predetermined amount of time.

14. The method of claim 13 , wherein the management module is further configured to utilize the first read data and second read data in the buffer to determine the cause of a system exception associated with one of the plurality of read commands.

15. The method of claim 14 , wherein the memory buffer is further configured to store information identifying which of the first memory segment and the second memory segment was read from last and alternate between the first memory segment and the second memory segment based on the information, and wherein the management module is further configured to utilize the information in the buffer to determine the cause of the system exception.

16. The method of claim 13 , wherein the memory buffer is further configured to compare the first read data and the second read data and, if the first read data and the second read data do not match, hold the first read data and the second read data in the memory buffer until the management module can utilize the first read data and the second read data to determine the cause of a system exception associated with one of the plurality of read commands.

17. The method of claim 16 , wherein the management module is further configured to determine whether one of the first read data and the second read data includes an error.