Microsoft Technology Licensing, LLC

Cornel Emilian Rat

William R Tipton

Rajsekhar Das

Chesong Lee

Karan Mehra

Surendra Verma

Erik G Hortsch

Raj Das

Arushi Aggarwal

Embodiments described herein relate to testing the integrity of a storage system's metadata while corresponding structured data remains online. Embodiments also relate to enabling corrupt storage system metadata to be repaired while the metadata remains in use and while its structured data remains online. Corruption detection and repair is described with respect to allocation metadata and reference count metadata. The embodiments are applicable to many types of storage systems, including file systems and databases, for example.

Online repair of metadata for structured data including file systems

A file system can allocate data of a storage system into data units, wherein a set of data units can be grouped into a storage region within a volume. A process of verifying validity of data within a storage region can include obtaining a first set of error-detecting codes from a subset of the data stored in a storage system, such as from a data unit of a file system object. Each of the first set of error-detecting codes can be associated with a corresponding data unit within the storage region. A second set of error-detecting codes can be generated based at least in part on the first set of error-detecting codes, and the second set of error-detecting codes can be associated with the storage region so that the second set of error-detecting codes can be used to verify the validity of the data within the storage region.

Efficient detection of corrupt data

A file system allows a different checksum algorithm to be used for different extents of a file system object independently of other extents of the file system object. The checksum algorithm can be a selectable attribute of an extent or range of extents of a file system object, such that some extents of a file system object can use a first checksum algorithm, while other extents of the file system object can use a second checksum algorithm. An extent of the file system object also may have no associated checksum algorithm. The file system stores, for each extent of a file system object, data indicating a checksum for the extent and an indication of any checksum algorithm used for the extent.

File system with per-extent checksums

Embodiments are directed to efficiently managing data storage and efficiently storing data. In one scenario, a computer system receives a write request addressed to one portion of data storage within a data store. The computer system redirects the received write request to another portion of data storage which includes storage containers, each of which is a logically specified portion of the data store. The computer system determines which storage container the write request is to write to, and identifies a storage container that is to be de-staged from the second portion of data storage to the first portion of data storage. The computer system then de-stages the identified storage containers to the first portion of data storage, the data of the de-staged container being stored on the first portion of data storage in the same order in which the data was stored in the identified storage container prior to de-staging.

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Bothell, WA, United States of America

Cornel Emilian Rat