Abstract: A technique for error detection is provided. A controller is configured to detect errors by using error correcting code (ECC), and a cache includes independent ECC words for storing data. The controller detects the errors in the ECC words for a wordline that is read. The controller detects a first error in a first ECC word on the wordline and a second error in a second ECC word on the wordline. The controller determines that the wordline is a failing wordline based on detecting the first error in the first ECC word and the second error in the second ECC word.

Abstract: Channel marking is provided in a memory system that includes a memory channel with a plurality of memory devices. The memory devices are arranged into a first group of memory devices and a second group of memory devices. The memory system is configured to perform a method that includes determining that more than a threshold number of memory devices in the first group are failing. An error correction code (ECC) is configured to compensate for errors associated with memory devices in the first group on the memory channel and to perform error correction on errors associated with memory devices in the second group on the memory channel.

Abstract: Embodiments relate to stale data detection in a marked channel for a scrub. An aspect includes bringing the marked channel online, wherein the computer comprises a plurality of memory channels comprising the marked channel and a remaining plurality of unmarked channels. Another aspect includes performing a scrub read of an address in the plurality of memory channels. Another aspect includes determining whether data returned by the scrub read from the marked channel is valid or stale based on data returned from the unmarked channels by the scrub read. Another aspect includes based on determining that the data returned by the scrub read from the marked channel is valid, not performing a scrub writeback to the marked channel. Another aspect includes based on determining that the data returned by the scrub read from the marked channel is stale, performing a scrub writeback of corrected data to the marked channel.

Abstract: A computer-system implemented method for dual asynchronous and synchronous memory operation in a memory subsystem includes establishing a synchronous channel between a memory controller and a memory buffer chip. A mode selector determines a reference clock source for a memory domain phase-locked loop of the memory buffer chip based on an operating mode of the memory buffer chip. An output of a nest domain phase-locked loop is provided as the reference clock source to the memory domain phase-locked loop in the memory buffer chip based on the operating mode being synchronous. The nest domain phase-locked loop is operable synchronous to a memory controller phase-locked loop of the memory controller. A separate reference clock is provided independent of the nest domain phase-locked loop as the reference clock to the memory domain phase-locked loop based on the operating mode being asynchronous.

Abstract: A computer implemented method for early data delivery prior to error detection completion in a memory system includes receiving a frame of a multi-frame data block at a memory control unit interface. A controller writes the frame to a buffer control block in a memory controller nest domain. The frame is read from the buffer control block by a cache subsystem interface in a system domain prior to completion of error detection of the multi-frame data block. Error detection is performed on the frame by an error detector in the memory controller nest domain. Based on detecting an error in the frame, an intercept signal is sent from the memory controller nest domain to a correction pipeline in the system domain. The intercept signal indicates that error correction is needed prior to writing data in the frame to a cache subsystem.

Abstract: A technique for error detection is provided. A controller is configured to detect errors by using error correcting code (ECC), and a cache includes independent ECC words for storing data. The controller detects the errors in the ECC words for a wordline that is read. The controller detects a first error in a first ECC word on the wordline and a second error in a second ECC word on the wordline. The controller determines that the wordline is a failing wordline based on detecting the first error in the first ECC word and the second error in the second ECC word.

Abstract: Providing homogeneous recovery in a redundant memory system that includes a memory controller, a plurality of memory channels in communication with the memory controller, an error detection code mechanism configured for detecting a failing memory channel, and an error recovery mechanism. The error recovery mechanism is configured for receiving notification of the failing memory channel, for blocking off new operations from starting on the memory channels, for completing any pending operations on the memory channels, for performing a recovery operation on the memory channels and for starting the new operations on at least a first subset of the memory channels. The memory system is capable of operating with the first subset of the memory channels.

Abstract: Embodiments relate to stale data detection in a marked channel for a scrub. An aspect includes bringing the marked channel online, wherein the computer comprises a plurality of memory channels comprising the marked channel and a remaining plurality of unmarked channels. Another aspect includes performing a scrub read of an address in the plurality of memory channels. Another aspect includes determining whether data returned by the scrub read from the marked channel is valid or stale based on data returned from the unmarked channels by the scrub read. Another aspect includes based on determining that the data returned by the scrub read from the marked channel is valid, not performing a scrub writeback to the marked channel. Another aspect includes based on determining that the data returned by the scrub read from the marked channel is stale, performing a scrub writeback of corrected data to the marked channel.

Abstract: Dynamic graduated memory device protection in redundant array of independent memory (RAIM) systems that include a plurality of memory devices is provided. A first severity level of a first failing memory device in the plurality of memory devices is determined. The first failing memory device is associated with an identifier used to communicate a location of the first failing memory device to an error correction code (ECC). A second severity level of a second failing memory device in the plurality of memory devices is determined. It is determined that the second severity level is higher than the first severity level. The identifier from the first failing memory device is removed based on determining that the second severity level is higher than the first severity level. The identifier is applied to the second failing memory device based on determining that the second severity level is higher than the first severity level.

Abstract: Dynamic graduated memory device protection in redundant array of independent memory (RAIM) systems that include a plurality of memory devices is provided. A first severity level of a first failing memory device in the plurality of memory devices is determined. The first failing memory device is associated with an identifier used to communicate a location of the first failing memory device to an error correction code (ECC). A second severity level of a second failing memory device in the plurality of memory devices is determined. It is determined that the second severity level is higher than the first severity level. The identifier from the first failing memory device is removed based on determining that the second severity level is higher than the first severity level. The identifier is applied to the second failing memory device based on determining that the second severity level is higher than the first severity level.

Abstract: Embodiments relate to early data delivery prior to error detection completion in a memory system. One aspect is a system that includes a cache subsystem interface with a correction pipeline in a system domain. The system includes a memory control unit interface in a memory controller nest domain and a buffer control block providing an asynchronous boundary layer between the system domain and the memory controller nest domain. A controller is configured to receive a frame of a multi-frame data block and write the frame to the buffer control block. The frame is read by the cache subsystem interface prior to completion of error detection of the multi-frame data block. Error detection is performed on the frame in the memory controller nest domain. Based on detecting an error in the frame, an intercept signal is sent from the memory controller nest domain to the correction pipeline in the system domain.

Abstract: Embodiments relate to first-in-first-out (FIFO) queue based command spreading. An aspect includes receiving a plurality of commands by a first level priority stage of a memory control unit (MCU), wherein each of the plurality of commands is associated with one of a plurality of ports located on a buffer chip. Another aspect includes storing each of the plurality of commands in a FIFO queue of a plurality of FIFO queues in the MCU, wherein each of the plurality of commands is assigned to a FIFO queue based on the command's associated port, and each of the plurality of FIFO queues is associated with a respective one of the plurality of ports located on the buffer chip. Another aspect includes selecting a FIFO queue of the plurality of FIFO queues and forwarding a command from the selected FIFO queue to the buffer chip by the second level priority stage.

Abstract: Embodiments relate to a dual asynchronous and synchronous memory system. One aspect is a system that includes a memory controller and a memory buffer chip coupled to the memory controller via a synchronous channel. The memory buffer chip includes a memory buffer unit configured to synchronously communicate with the memory controller in a nest domain, and a memory buffer adaptor configured to communicate with at least one memory interface port in a memory domain. The at least one memory interface port is operable to access at least one memory device. A boundary layer is connected to the nest domain and the memory domain, where the boundary layer is configurable to operate in a synchronous transfer mode between the nest and memory domains and to operate in an asynchronous transfer mode between the nest and memory domains.

Abstract: Embodiments relate to out-of-synchronization detection and out-of-order detection in a memory system. One aspect is a system that includes a plurality of channels, each providing communication with a memory buffer chip and a plurality of memory devices. A memory control unit is coupled to the plurality of channels. The memory control unit is configured to perform a method that includes receiving frames on two or more of the channels. The memory control unit identifies alignment logic input in each of the received frames and generates a summarized input to alignment logic for each of the channels of the received frames based on the alignment logic input. The memory control unit adjusts a timing alignment based on a skew value per channel. Each of the timing adjusted summarized inputs is compared. Based on a mismatch between at least two of the timing adjusted summarized inputs, a miscompare signal is asserted.

Abstract: Embodiments relate to replay suspension in a memory system. One aspect is a system that includes a replay buffer coupled to a memory controller interface, and a replay control coupled to the replay buffer and a memory controller. The replay control is configured to receive an error indication associated with sending data from the memory controller interface to a memory subsystem as part of an operation. A replay pending signal is provided to the memory controller based on the error indication. Based on waiting for a period of time sufficient for the memory controller to provide remaining data associated with the operation to the replay buffer, a replay signal is asserted.

Abstract: Embodiments relate to address mapping including generic bits. An aspect includes receiving an address including generic bits from a memory control unit (MCU) by a buffer module in a main memory. Another aspect includes mapping the generic bits to an address format corresponding to a type of dynamic random access memory (DRAM) in a memory subsystem associated with the buffer module by the buffer module. Yet another aspect includes accessing a physical location in the DRAM in the memory subsystem by the buffer module based on the mapped generic bits.

Abstract: Embodiments relate to reestablishing synchronization across multiple channels in a memory system. One aspect is a system that includes a plurality of channels, each providing communication with a memory buffer chip and a plurality of memory devices. A memory control unit is coupled to the plurality of channels. The memory control unit is configured to perform a method that includes receiving an out-of-synchronization indication associated with at least one of the channels. The memory control unit performs a first stage of reestablishing synchronization that includes selectively stopping new traffic on the plurality of channels, waiting for a first time period to expire, resuming traffic on the plurality of channels based on the first time period expiring, and verifying that synchronization is reestablished for a second time period.

Abstract: Embodiments relate to first-in-first-out (FIFO) queue based command spreading. An aspect includes receiving a plurality of commands by a first level priority stage of a memory control unit (MCU), wherein each of the plurality of commands is associated with one of a plurality of ports located on a buffer chip. Another aspect includes storing each of the plurality of commands in a FIFO queue of a plurality of FIFO queues in the MCU, wherein each of the plurality of commands is assigned to a FIFO queue based on the command's associated port, and each of the plurality of FIFO queues is associated with a respective one of the plurality of ports located on the buffer chip. Another aspect includes selecting a FIFO queue of the plurality of FIFO queues and forwarding a command from the selected FIFO queue to the buffer chip by the second level priority stage.

Abstract: Marking memory chips as faulty when a fault is detected in data from the memory chip. Upon detecting that a plurality of memory chips are faulty, determining which of a plurality of memory channels contains the faulty memory chips. Marking one of a plurality of memory channels as failing in response to determining that the number of failing memory chips has exceeded a threshold.

Abstract: Embodiments relate to a method including detecting a first error when reading a first cache line, recording a first address of the first error, detecting a second error when reading a second cache line and recording a second address of the second error. Embodiments also include comparing the first and second bitline address, comparing the first and second wordline address, activating a bitline delete mode based on matching first and second bitline addresses and not matching the first and second wordline addresses, detecting a third error when reading a third cache line, recording a third bitline address of the third error, comparing the second bitline address to a third bitline address and deleting a location corresponding to the third cache line from available cache locations based on the activated bitline delete mode and the third bitline address matching the second bitline address.