Adjusting Redundancy In An Erasure Code Object Store To Account For Varying Data Value

摘要

Example apparatus and methods control the number of rateless erasure codes (e.g., fountain codes) stored in an object store for an item (e.g., file stored as object). The codes for the item may be generated according to an M/N policy. A first safety factor that controls how many codes are stored initially in the object store is identified. A first number of codes are then stored in the object store, where the first number is selected as a function of the first safety factor. A second safety factor for the item and a condition under which the second safety factor is to be used to control the number of codes to be stored in the object store is also identified. When the condition is detected, a second number of codes are stored in the object store, where the second number is selected as a function of the second safety factor.

主权项

1. A non-transitory computer-readable storage medium storing computer-executable instructions that when executed by a computer cause the computer to perform a method, the method comprising:
accessing a set of rateless erasure codes generated for an item, where the rateless erasure codes were generated according to an M/N policy, M and N being integers, M being greater than N, N−M being a minimum number of the set of M rateless erasure codes from which the item can be reconstructed; identifying a first safety factor for the item, where the first safety factor controls how many members of the set of rateless erasure codes are to be stored in an object store; selecting a first number of the set of rateless erasure codes to be stored in the object store, where the first number is selected based, at least in part, on the first safety factor; providing the first number of rateless erasure codes to the object store; identifying a second safety factor for the item and a condition under which the second safety factor is to be used to control how many members of the set of rateless erasure codes are to be stored in the object store; and upon detecting the condition:
selecting a second number of the set of rateless erasure codes to be stored in the object store, where the second number is selected based, at least in part, on the second safety factor; andproviding the second number of rateless erasure codes to the object store.