Mass storage controller with apparatus and method for extending battery backup time by selectively providing battery power to volatile memory banks not storing critical data
First Claim
1. A write-caching mass storage controller, comprising:
- a plurality of volatile memory banks, each having separate power inputs;
a battery, coupled to provide power to said plurality of volatile memory banks via said separate power inputs during a main power loss;
a processor, coupled to said plurality of volatile memory banks, configured to control storage of critical data to a first subset of said plurality of volatile memory banks and to refrain from controlling storage of said critical data to a second subset of said plurality of volatile memory banks, wherein said first and second subset are mutually exclusive, wherein said critical data comprises data which must be retained during said main power loss to avoid loss of write-cached user data; and
control logic, coupled to receive information from said processor indicating said first and second subsets of said plurality of volatile memory banks, configured to detect said loss of main power, and to disable said second subset of said plurality of volatile memory banks from receiving power from said battery in response to detecting said loss of main power.
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Abstract
A battery-backed write-caching mass storage controller is disclosed. The controller includes a plurality of volatile memory banks for caching write data prior to being written to disk drives. Critical data is stored into a first subset of the memory banks, leaving a second subset of memory banks storing only non-critical data. Critical data is data that must be retained during a main power loss to avoid loss of write-cached user data. Critical data includes the write-cached user data itself, as well as metadata describing the write-cached user data. When the controller detects a loss of main power, the controller causes the critical memory banks to receive battery power, but disables battery power to the non-critical memory banks in order to extend the length of time the critical memory banks can continue to receive battery power to reduce the likelihood of user data loss.
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Citations
40 Claims
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1. A write-caching mass storage controller, comprising:
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a plurality of volatile memory banks, each having separate power inputs;
a battery, coupled to provide power to said plurality of volatile memory banks via said separate power inputs during a main power loss;
a processor, coupled to said plurality of volatile memory banks, configured to control storage of critical data to a first subset of said plurality of volatile memory banks and to refrain from controlling storage of said critical data to a second subset of said plurality of volatile memory banks, wherein said first and second subset are mutually exclusive, wherein said critical data comprises data which must be retained during said main power loss to avoid loss of write-cached user data; and
control logic, coupled to receive information from said processor indicating said first and second subsets of said plurality of volatile memory banks, configured to detect said loss of main power, and to disable said second subset of said plurality of volatile memory banks from receiving power from said battery in response to detecting said loss of main power. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for reducing battery power consumption during a main power loss to reduce the likelihood of loss of user write-cached data in a write-caching mass storage controller, comprising:
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storing information indicating first and second subsets of a plurality of volatile memory banks of the controller, wherein each of the first and second subsets are configured to separately receive power from the battery, wherein the first and second subset are mutually exclusive;
storing critical data to the first subset of the plurality of volatile memory banks in exclusion of the second subset of the plurality of volatile memory banks, after said storing the information, wherein the critical data comprises data which must be retained during the main power loss to avoid loss of write-cached user data;
detecting the main power loss, after said storing the critical data; and
disabling the second subset of the plurality of volatile memory banks from receiving power from the battery in response to detecting the loss of main power. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A write-caching mass storage controller, comprising:
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a plurality of volatile memory banks, each having separate power inputs;
a battery, coupled to provide power to said plurality of volatile memory banks via said separate power inputs, during a main power loss; and
a processor, coupled to said plurality of volatile memory banks, configured to control storage of critical data to a first subset of said plurality of volatile memory banks and to refrain from controlling storage of said critical data to a second subset of said plurality of volatile memory banks, wherein said first and second subset are mutually exclusive, wherein said critical data comprises data which must be retained during said main power loss to avoid loss of write-cached user data, said processor further configured to detect said loss of main power, and to responsively disable said second subset of said plurality of volatile memory banks from receiving power from said battery. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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Specification