RAID controller using capacitor energy source to flush volatile cache data to non-volatile memory during main power outage

A write-caching redundant array of inexpensive disks (RAID) controller, comprising:

• a volatile memory;
• a non-volatile memory;
• a central processing unit (CPU), for managing transfers of posted-write data from host computers to said volatile memory and transfers of said posted-write data from said volatile memory to storage devices when a main power source is supplying power to the RAID controller, wherein said CPU is configured to program a source location into a register of a memory controller prior to a loss of main power;
• the memory controller, coupled to said volatile memory and said non-volatile memory, wherein said memory controller is configured to buffer said transfers of said posted-write data from said host computers to said volatile memory and said transfers of said posted-write data from said volatile memory to said storage devices when said main power source is supplying power to the RAID controller, wherein said memory controller, rather than said CPU, is configured to flush said posted-write data from said volatile memory to said non-volatile memory when said main power source fails to supply power to the RAID controller, wherein said memory controller comprises said register for specifying said source location of said posted-write data in said volatile memory, wherein said memory controller flushes said posted-write data from said source location specified in said register to said non-volatile memory;
• and
• at least one capacitor, coupled to provide power to said memory controller, said volatile memory, and said non-volatile memory when said main power supply fails to supply power to the RAID controller, wherein said CPU is excluded from receiving power from said at least one capacitor when said main power supply fails to supply power to the RAID controller.

A write-caching redundant array of inexpensive disks (RAID) controller, comprising:

• a volatile memory;
• a non-volatile memory;
• a central processing unit (CPU), for managing transfers of posted-write data from host computers to said volatile memory and transfers of said posted-write data from said volatile memory to storage devices when a main power source is supplying power to the RAID controller, wherein said CPU is configured to program a source location into a first register of a memory controller and program a destination location into a second register of said memory controller prior to a loss of main power;
• a memory controller, coupled to said volatile memory and said non-volatile memory, wherein said memory controller is configured to buffer said transfers of said posted-write data from said host computers to said volatile memory and said transfers of said posted-write data from said volatile memory to said storage devices when said main power source is supplying power to the RAID controller, wherein said memory controller, rather than said CPU, is configured to flush said posted-write data from said volatile memory to said non-volatile memory when said main power source fails to supply power to the RAID controller, wherein said memory controller comprises said first register for specifying said source location of said posted-write data in said volatile memory and said second register for specifying said destination location of said posted-write data in said non-volatile memory, wherein said memory controller flushes said posted-write data from said source location specified in said first register to said destination location specified in said second register in said non-volatile memory;
• and
• at least one capacitor, coupled to provide power to said memory controller, said volatile memory, and said non-volatile memory when said main power supply fails to supply power to the RAID controller, wherein said CPU is excluded from receiving power from said at least one capacitor when said main power supply fails to supply power to the RAID controller.

A write-caching redundant array of inexpensive disks (RAID) controller, comprising:

• a volatile memory;
• a non-volatile memory;
• a central processing unit (CPU), for managing transfers of posted-write data from host computers to said volatile memory and transfers of said posted-write data from said volatile memory to storage devices when a main power source is supplying power to the RAID controller, wherein said posted-write data is comprised in a plurality of non-contiguous regions in said volatile memory, wherein said CPU is configured to program information specifying said plurality of non-contiguous regions into a memory controller prior to said loss of main power;
• the memory controller, coupled to said volatile memory and said non-volatile memory, wherein said memory controller is configured to buffer said transfers of said posted-write data from said host computers to said volatile memory and said transfers of said posted-write data from said volatile memory to said storage devices when said main power source is supplying power to the RAID controller, wherein said memory controller, rather than said CPU, is configured to flush said posted-write data from said volatile memory to said non-volatile memory when said main power source fails to supply power to the RAID controller;
• and
• at least one capacitor, coupled to provide power to said memory controller, said volatile memory, and said non-volatile memory when said main power supply fails to supply power to the RAID controller, wherein said CPU is excluded from receiving power from said at least one capacitor when said main power supply fails to supply power to the RAID controller.

A write-caching redundant array of inexpensive disks (RAID) controller, comprising:

• a volatile memory;
• a non-volatile memory;
• a central processing unit (CPU), for managing transfers of posted-write data from host computers to said volatile memory and transfers of said posted-write data from said volatile memory to storage devices when a main power source is supplying power to the RAID controller;
• a memory controller, coupled to said volatile memory and said non-volatile memory, wherein said memory controller is configured to buffer said transfers of said posted-write data from said host computers to said volatile memory and said transfers of said posted-write data from said volatile memory to said storage devices when said main power source is supplying power to the RAID controller, wherein said memory controller, rather than said CPU, is configured to flush said posted-write data from said volatile memory to said non-volatile memory when said main power source fails to supply power to the RAID controller, wherein said memory controller is configured to indicate to a power manager whether said memory controller is presently flushing said posted-write data from said volatile memory to said non-volatile memory, wherein said memory controller is further configured to indicate to said power manager whether an error occurred when said memory controller attempted to flush said posted-write data from said volatile memory to said non-volatile memory;
• at least one capacitor, coupled to provide power to said memory controller, said volatile memory, and said non-volatile memory when said main power supply fails to supply power to the RAID controller, wherein said CPU is excluded from receiving power from said at least one capacitor when said main power supply fails to supply power to the RAID controller;
• and
• the power manager, coupled to said memory controller, configured to detect said loss of main power, and to signal said memory controller to flush said posted-write data from said volatile memory to said non-volatile memory in response thereto.

A method for preserving posted-write data in a write-caching redundant array of inexpensive disks (RAID) controller, the method comprising:

• supplying power, by at least one capacitor, to a volatile memory, a non-volatile memory, and a memory controller of the RAID controller, in response to a loss of main power to the RAID controller, wherein said memory controller comprises a register for specifying a source location of said posted-write data in said volatile memory, wherein said memory controller flushes said posted-write data from said source location specified in said register to said non-volatile memory;
• foregoing supplying power, by the at least one capacitor, to a central processing unit (CPU) of the RAID controller, in response to the loss of main power to the RAID controller, wherein the CPU manages transfers of the posted-write data from host computers to the volatile memory and transfers of the posted-write data from the volatile memory to storage devices when main power is being supplied to the RAID controller prior to the loss thereof, wherein the memory controller buffers the transfers of the posted-write data from the host computers to the volatile memory and the transfers of the posted-write data from the volatile memory to the storage devices when the main power is being supplied to the RAID controller prior to the loss thereof, wherein said CPU is configured to program said source location into said register of said memory controller prior to said loss of main power;
• and
• flushing posted-write data, by the memory controller rather than by the CPU, from the volatile memory to the non-volatile memory, in response to the loss of main power.

A method for preserving posted-write data in a write-caching redundant array of inexpensive disks (RAID) controller, the method comprising:

• supplying power, by at least one capacitor, to a volatile memory, a non-volatile memory, and a memory controller of the RAID controller, in response to a loss of main power to the RAID controller, wherein said memory controller comprises a first register for specifying a source location of said posted-write data in said volatile memory and a second register for specifying a destination location of said posted-write data in said non-volatile memory, wherein said memory controller flushes said posted-write data from said source location specified in said first register to said destination location specified in said second register;
• foregoing supplying power, by the at least one capacitor, to a central processing unit (CPU) of the RAID controller, in response to the loss of main power to the RAID controller, wherein the CPU manages transfers of the posted-write data from host computers to the volatile memory and transfers of the posted-write data from the volatile memory to storage devices when main power is being supplied to the RAID controller prior to the loss thereof, wherein the memory controller buffers the transfers of the posted-write data from the host computers to the volatile memory and the transfers of the posted-write data from the volatile memory to the storage devices when the main power is being supplied to the RAID controller prior to the loss thereof, wherein said CPU is configured to program said destination location into said second register of said memory controller prior to said loss of main power;
• and
• flushing posted-write data, by the memory controller rather than by the CPU, from the volatile memory to the non-volatile memory, in response to the loss of main power.

A method for preserving posted-write data in a write-caching redundant array of inexpensive disks (RAID) controller, wherein said posted-write data is comprised in a plurality of non-contiguous regions in a volatile memory, the method comprising:

• supplying power, by at least one capacitor, to said volatile memory, a non-volatile memory, and a memory controller of the RAID controller, in response to a loss of main power to the RAID controller;
• foregoing supplying power, by the at least one capacitor, to a central processing unit (CPU) of the RAID controller, in response to the loss of main power to the RAID controller, wherein the CPU manages transfers of the posted-write data from host computers to the volatile memory and transfers of the posted-write data from the volatile memory to storage devices when main power is being supplied to the RAID controller prior to the loss thereof, wherein the memory controller buffers the transfers of the posted-write data from the host computers to the volatile memory and the transfers of the posted-write data from the volatile memory to the storage devices when the main power is being supplied to the RAID controller prior to the loss thereof, wherein said CPU is configured to program information specifying said plurality of non-contiguous regions into said memory controller prior to said loss of main power;
• and
• flushing posted-write data, by the memory controller rather than by the CPU, from the volatile memory to the non-volatile memory, in response to the loss of main power.

A method for preserving posted-write data in a write-caching redundant array of inexpensive disks (RAID) controller, the method comprising:

• supplying power, by at least one capacitor, to a volatile memory, a non-volatile memory, a memory controller, and a power manager of the RAID controller, in response to a loss of main power to the RAID controller, wherein the power manager is coupled to said memory controller, configured to detect said loss of main power, and to signal said memory controller to flush said posted-write data from said volatile memory to said non-volatile memory in response thereto, wherein said memory controller is configured to indicate to said power manager whether said memory controller is presently flushing said posted-write data from said volatile memory to said non-volatile memory, wherein said memory controller is further configured to indicate to said power manager whether an error occurred when said memory controller attempted to flush said posted-write data from said volatile memory to said non-volatile memory;
• foregoing supplying power, by the at least one capacitor, to a central processing unit (CPU) of the RAID controller, in response to the loss of main power to the RAID controller, wherein the CPU manages transfers of the posted-write data from host computers to the volatile memory and transfers of the posted-write data from the volatile memory to storage devices when main power is being supplied to the RAID controller prior to the loss thereof, wherein the memory controller buffers the transfers of the posted-write data from the host computers to the volatile memory and the transfers of the posted-write data from the volatile memory to the storage devices when the main power is being supplied to the RAID controller prior to the loss thereof;
• and
• flushing posted-write data, by the memory controller rather than by the CPU, from the volatile memory to the non-volatile memory, in response to the loss of main power.