High reliability erasure code distribution

摘要

Example apparatus and methods treat some erasure codes differently than other erasure codes. For example, erasure codes that are only involved in error-recovery may never be read and thus may be stored using a different approach than erasure codes that are involved in more regular data reading. If different types of data stores are available, then the erasure codes that are more likely to be read may be stored in data stores having a first (e.g., higher, faster) type of read performance while the erasure codes that are less likely to be read may be stored in data stores having a second (e.g., lower, slower, less expensive) type of read performance. Different data stores may be located on different data storage devices. Different data stores may even be located on a single data storage device.

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 n erasure codes generated for a message having k symbols, n and k being numbers, n being greater than or equal to k; identifying a first data store that is available to store members of the set of n erasure codes, where the first data store is located on cylinders on the outer half of a hard disk drive; identifying a second data store that is available to store members of the set of n erasure codes, where the second data store is located on cylinders on the inner half of a hard disk drive; identifying a property associated with both the first data store and the second data store, where the property is a speed with which an erasure code can be read from a data store, or where the property is a speed with which an erasure code can be written to a data store; identifying a first value for the property for the first data store; identifying a second value for the property for the second data store; selecting a first subset of the set of erasure codes to store in the first data store based, at least in part, on the first value or the second value, and selecting a second subset of the set of erasure codes to store in the second data store based, at least in part, on the first value or the second value.