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## Package org.apache.hadoop.fs.s3

A distributed, block-based implementation of `FileSystem` that uses Amazon S3 as a backing store.

See:
Description

Interface Summary
FileSystemStore | A facility for storing and retrieving `INode`s and `Block`s.

Class Summary
Block | Holds metadata about a block of data being stored in a `FileSystemStore`.
INode | Holds file metadata including type (regular file, or directory), and the list of blocks that are pointers to the data.
MigrationTool | This class is a tool for migrating data from an older to a newer version of an S3 filesystem.
S3Credentials | Extracts AWS credentials from the filesystem URI or configuration.
S3FileSystem | A block-based `FileSystem` backed by Amazon S3.

Exception Summary
S3Exception | Thrown if there is a problem communicating with Amazon S3.
S3FileSystemException | Thrown when there is a fatal exception while using `S3FileSystem`.
VersionMismatchException | Thrown when Hadoop cannot read the version of the data stored in `S3FileSystem`.

## Package org.apache.hadoop.fs.s3 Description

A distributed, block-based implementation of `FileSystem` that uses Amazon S3 as a backing store.

Files are stored in S3 as blocks (represented by `Block`), which have an ID and a length. Block metadata is stored in S3 as a small record (represented by `INode`) using the URL-encoded path string as a key. Inodes record the file type (regular file or directory) and the list of blocks. This design makes it easy to seek to any given position in a file by reading the inode data to compute which block to access, then using S3's support for HTTP Range headers to start streaming from the correct position. Renames are also efficient since only the inode is moved (by a DELETE followed by a PUT since S3 does not support renames).

For a single file /dir1/file1 which takes two blocks of storage, the file structure in S3 would be something like this:

    /
    /dir1
    /dir1/file1
    block-6415776850131549260
    block-3026438247347758425

Inodes start with a leading `/`, while blocks are prefixed with `block-`.

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