As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
An information handling system may include a power system including a rectifier for converting an alternating current (AC) voltage (e.g., as available from a public power grid) to a direct current (DC) voltage suitable for use by components of the information handling system. It is typical in existing information handling systems for a power system (also known as a power supply unit or PSU) to provide approximately 10 milliseconds of capacitive “hold-up time” which allows the power system and the information handling system to tolerate small input power disruptions without impacting the operational state of the information handling system. Of the approximately 10 milliseconds of hold-up time, eight to nine milliseconds may be required by a power system to filter out typical noise on alternating current input lines and to determine whether a loss of an alternating current power source has occurred. Thus, only approximately one to two milliseconds of hold-up time is provided to the information handling system, after the power system alerts (e.g., interrupts) the information handling system that the input power source has failed (e.g., by de-asserting an AC_OK signal or similar signal).
While such hold-up time may be sufficient for many applications, longer hold-up times may be desired or necessary to provide certain functionality to an information handling system. For example, non-volatile memory, which may be implemented using non-volatile dual inline memory modules (NVDIMMs) provide the capability to preserve the contents of volatile memory (e.g., dynamic random access memory) by copying the contents of the volatile memory to the non-volatile memory after a command to do so (e.g., after a power failure). Such back-up to non-volatile memory may occur in response to an alert (e.g., interrupt) by a power system to an information handling system indicative of a power failure, to which a memory system may respond by causing information handling resources of the information handling system (e.g., a processor) to flush their write buffers to volatile memory. This process may take one to two milliseconds to complete, and as write buffers increase, may require several more milliseconds of hold-up time in the future, which may serve as a limitation to use of non-volatile memory such as NVDIMMs given typical hold-up times of existing power systems.
Another limitation of non-volatile memory solutions such as NVDIMMs in conjunction with existing power systems is that processor write-back caching must often be disabled, as write-back caches may require approximately 30 milliseconds to perform a cache flush to write cache contents to memory after a power failure, and such duration exceeds the hold-up times of existing power systems.