United States Patent
US Patent 7380055: Apparatus and method in a cached raid controller…
US 7380055 · granted 2008-05-27
Abstract
An apparatus for reducing data unavailability time after a loss of main power in a storage controller is described. The controller backs up its volatile memory containing posted-write data to a non-volatile memory upon detecting a loss of main power. The controller continues to provide battery power to the volatile memory to sustain the posted-write data. If the battery is able to supply power to the volatile memory until main power is restored, the controller foregoes restoring the posted-write data to the volatile memory from the non-volatile memory. By not incurring the restore time, which may be substantial if the volatile memory is large since read rates from volatile memories are typically slow, the data unavailability time is reduced. The selective restore feature is user-disableable and also includes a brown-out timer for allowing a user to specify how long to battery-power the volatile memory if the feature is enabled.
| Patent Number | 7380055 |
|---|---|
| Title | Apparatus and method in a cached raid controller utilizing a solid state backup device for improving data availability time |
| Filed | 2005-02-09 |
| Granted | 2008-05-27 |
| Inventor(s) | Ashmore; Paul Andrew |
| Assignee | Dot Hill Systems Corporation |
| CPC Classification | G06F 12/00, G06F 13/00, G06F 13/28 |
| Number of Claims | 94 |
Abstract
An apparatus for reducing data unavailability time after a loss of main power in a storage controller is described. The controller backs up its volatile memory containing posted-write data to a non-volatile memory upon detecting a loss of main power. The controller continues to provide battery power to the volatile memory to sustain the posted-write data. If the battery is able to supply power to the volatile memory until main power is restored, the controller foregoes restoring the posted-write data to the volatile memory from the non-volatile memory. By not incurring the restore time, which may be substantial if the volatile memory is large since read rates from volatile memories are typically slow, the data unavailability time is reduced. The selective restore feature is user-disableable and also includes a brown-out timer for allowing a user to specify how long to battery-power the volatile memory if the feature is enabled.
Claim 1
A mass storage controller for providing improved data availability, comprising: a volatile memory, for storing posted-write data; a non-volatile memory, coupled to said volatilememory; a battery, coupled to supply power to said volatile memory in response to a loss of main power; an indicator, for indicating whether said battery continued to supply power to said volatile memory until said main power was restored wherein saidindicator comprises a storage element, coupled to receive power from said battery in response to said loss of main power, configured to provide a predetermined value when read after transitioning from a non-powered state to a powered state; and controllogic, coupled to said indicator, configured to: program said storage element to a value other than said predetermined value, in response to said loss of main power; backup said posted-write data from said volatile memory to said non-volatile memory, inresponse to said loss of main power; determine that the main power has been restored, after the control logic backs up said posted-write data from said volatile memory to said non-volatile memory; determine whether said indicator indicates the batterycontinued to sup
Claims
94 totalA mass storage controller for providing improved data availability, comprising: a volatile memory, for storing posted-write data; a non-volatile memory, coupled to said volatilememory; a battery, coupled to supply power to said volatile memory in response to a loss of main power; an indicator, for indicating whether said battery continued to supply power to said volatile memory until said main power was restored wherein saidindicator comprises a storage element, coupled to receive power from said battery in response to said loss of main power, configured to provide a predetermined value when read after transitioning from a non-powered state to a powered state; and controllogic, coupled to said indicator, configured to: program said storage element to a value other than said predetermined value, in response to said loss of main power; backup said posted-write data from said volatile memory to said non-volatile memory, inresponse to said loss of main power; determine that the main power has been restored, after the control logic backs up said posted-write data from said volatile memory to said non-volatile memory; determine whether said indicator indicates the batterycontinued to sup