Method and system for improved reliability in storage devices
First Claim
1. A method of preventing data loss during a voluntary disk drive power loss event and an involuntary primary power loss event, the method comprising:
- supplying write data from a host computer into a volatile write buffer;
transferring the write data directly from the volatile write buffer to a disk drive while disk drive power is present;
maintaining charge in an energy storage device;
supplying electrical power from the energy storage device upon detection of the involuntary primary power loss event, wherein the electrical power is supplied to at least the volatile write buffer and nonvolatile cache to save the write data to the non-volatile cache in an occurrence of the involuntary primary power loss event;
otherwise, moving the write data from volatile buffer into the nonvolatile cache during the voluntary disk drive power loss event while continuing to accept incoming data to the volatile buffer from the host computer;
transferring the write data from the nonvolatile cache to the disk drive upon cessation of the voluntary disk drive power loss event, whereby loss of the write data is prevented while the disk drive is temporarily powered down; and
wherein data flowing from the volatile write buffer directly into the disk drive bypasses the non-volatile cache while disk drive power is present.
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Accused Products
Abstract
A method of preventing data loss in a data storage system includes supplying write data to a high speed volatile write buffer and supplying electrical power from an energy storage device upon detection of a primary power loss event. The backup electrical power is supplied to the write buffer and nonvolatile cache. Under backup power, the write data is transferred into the nonvolatile cache and the backup power is removed. Upon regaining main power, a data presence indication triggers a transfer of the write data from the nonvolatile cache to the long term storage media. The method may be implemented for a system to protect it from inadvertent power losses or it may implemented in a system where the long term storage device is power cycled to save power. The energy storage device is not necessarily needed in the power cycled system unless power failure protection is also desired.
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Citations
23 Claims
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1. A method of preventing data loss during a voluntary disk drive power loss event and an involuntary primary power loss event, the method comprising:
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supplying write data from a host computer into a volatile write buffer; transferring the write data directly from the volatile write buffer to a disk drive while disk drive power is present; maintaining charge in an energy storage device; supplying electrical power from the energy storage device upon detection of the involuntary primary power loss event, wherein the electrical power is supplied to at least the volatile write buffer and nonvolatile cache to save the write data to the non-volatile cache in an occurrence of the involuntary primary power loss event; otherwise, moving the write data from volatile buffer into the nonvolatile cache during the voluntary disk drive power loss event while continuing to accept incoming data to the volatile buffer from the host computer; transferring the write data from the nonvolatile cache to the disk drive upon cessation of the voluntary disk drive power loss event, whereby loss of the write data is prevented while the disk drive is temporarily powered down; and wherein data flowing from the volatile write buffer directly into the disk drive bypasses the non-volatile cache while disk drive power is present. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for saving data during a power loss, the system comprising:
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a write data interface that supplies write data from a host computer to be written into long term storage media; a volatile write buffer for accepting the write data from the data interface; a nonvolatile cache to store the write data at least during a power loss; an energy storage device for delivering backup power during an involuntary loss of a primary power source; and a controller for controlling the flow of the write data during normal powered operations, during a loss of primary power, and during a voluntary power loss of the disk drive, wherein; during the normal powered operations, data from the volatile write buffer flows directly into the long term storage media and bypasses the non-volatile cache while primary power is present; during the voluntary power loss of the disk drive, the controller configures the system to store constantly incoming write data from the host computer into the volatile write buffer and transfers the stored constantly incoming write data from the volatile write buffer to the nonvolatile cache; and during the involuntary loss of primary power, the controller routes backup power to at least the volatile write buffer and nonvolatile cache and transfers the write data such that any write data residing in the volatile write buffer upon primary power loss is moved to the nonvolatile cache. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method of preventing data loss, the method comprising:
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supplying write data from a host computer into a write buffer; transferring the write data in the write buffer directly into a target disk storage device and bypassing non-volatile cache while power is supplied to the target disk storage device; moving the write data into the nonvolatile cache upon detection that the target disk storage device has been power cycled off, wherein the host computer continues to supply write data while the target storage device has been powered off; and transferring the write data from the nonvolatile cache to the target disk storage device upon detection that the target disk storage device has been power cycled on whereby loss of the write data is prevented during a power cycle event. - View Dependent Claims (20)
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21. A system for protecting data, the system comprising:
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a write data interface connected to a host computer that supplies write data to be written to a disk storage device; a volatile write buffer for accepting the write data from the data interface; a nonvolatile cache to store the write data at least during a power cycling off event of the disk storage device, wherein the host computer continues to supply write data during the power cycling off event of the disk storage device, and wherein the nonvolatile cache is bypassed by flowing the write data directly from the volatile buffer to the disk storage device when power is supplied to the disk storage device; and means for; detecting at least one of a power cycling off event and presence of write data in the volatile write buffer; transferring the write data from the volatile write buffer to the nonvolatile cache; and detecting a power cycling on event and transferring the write data in the nonvolatile cache to the disk storage device. - View Dependent Claims (22, 23)
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Specification