Semi-static distribution technique
AssigneeNetwork Appliance, Inc.
InventorsPeter F. Corbett, Steven R. Kleiman, Robert M. English
Life of this patent
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Abstract
A semi-static distribution technique distributes parity across disks of an array. According to the technique, parity is distributed (assigned) across the disks of the array in a manner that maintains a fixed pattern of parity blocks among the stripes of the disks. When one or more disks are added to the array, the semi-static technique redistributes parity in a way that does not require recalculation of parity or moving of any data blocks. Notably, the parity information is not actually moved; the technique merely involves a change in the assignment (or reservation) for some of the parity blocks of each pre-existing disk to the newly added disk.
Claims20
A method for distributing parity blocks across a set of storage devices of a system, comprising:
- adding a new storage device to a set of pre-existing storage devices of the system to thereby provide N storage devices, where N is equal to number of pre-existing storage devices plus the new storage device;
- and
- moving every Nth parity block to the new storage device from the set of pre-existing storage devices to arrange approximately 1/N parity blocks on each storage device.
A system to distribute parity blocks across a set of storage devices, comprising:
- the set of storage devices comprising a set of pre-existing storage devices and a new storage device to thereby provide N storage devices, where N is equal to number of pre-existing storage devices plus the new storage device;
- and
- a storage module configured to move every Nth parity block to the new storage device from the set of pre-existing storage devices to arrange approximately 1/N parity blocks on each storage device.
An apparatus for distributing parity blocks across a set of storage devices of a system, comprising:
- means for adding a new storage device to a set of pre-existing storage devices of the system to thereby provide N storage devices, where N is equal to number of pre-existing storage devices plus the new storage device;
- and
- means for moving every Nth parity block to the new storage device from the set of pre-existing storage devices to arrange approximately 1/N parity blocks on each storage device.
A computer readable medium containing executable program instructions for distributing parity blocks across a set of storage devices of a system, comprising:
- adding a new storage device to a set of pre-existing storage devices of the system to thereby provide N storage devices, where N is equal to number of pre-existing storage devices plus the new storage device;
- and
- moving every Nth parity block to the new storage device from the set of pre-existing storage devices to arrange approximately 1/N parity blocks on each storage device.
Dependencies are inferred from the claim text.