在线存储数据的文件系统 S3QL 1.7 发布

     <p>S3QL 是个用来在线存储数据的文件系统，支持 Amazon S3 、SFTP 服务器等。</p>    <h3>Features</h3>    <ul>     <li><strong>Transparency.</strong> Conceptually, S3QL is indistinguishable from a local file system. For example, it supports hardlinks, symlinks, ACLs and standard unix permissions, extended attributes and file sizes up to 2 TB. </li>    </ul>    <ul>     <li><strong>Dynamic Size.</strong> The size of an S3QL file system grows and shrinks dynamically as required. </li>    </ul>    <ul>     <li><strong>Compression.</strong> Before storage, all data may compressed with the LZMA, bzip2 or deflate (gzip) algorithm. </li>    </ul>    <ul>     <li><strong>Encryption.</strong> After compression (but before upload), all data can AES encrypted with a 256 bit key. An additional SHA256 HMAC checksum is used to protect the data against manipulation. </li>    </ul>    <ul>     <li><strong>Data De-duplication.</strong> If several files have identical contents, the redundant data will be stored only once. This works across all files stored in the file system, and also if only some parts of the files are identical while other parts differ. </li>    </ul>    <ul>     <li><strong>Immutable Trees.</strong> Directory trees can be made immutable, so that their contents can no longer be changed in any way whatsoever. This can be used to ensure that backups can not be modified after they have been made. </li>    </ul>    <ul>     <li><strong>Copy-on-Write/Snapshotting.</strong> S3QL can replicate entire directory trees without using any additional storage space. Only if one of the copies is modified, the part of the data that has been modified will take up additional storage space. This can be used to create intelligent snapshots that preserve the state of a directory at different points in time using a minimum amount of space. </li>    </ul>    <ul>     <li><strong>High Performance independent of network latency.</strong> All operations that do not write or read file contents (like creating directories or moving, renaming, and changing permissions of files and directories) are very fast because they are carried out without any network transactions. S3QL achieves this by saving the entire file and directory structure in a database. This database is locally cached and the remote copy updated asynchronously. </li>    </ul>    <ul>     <li><strong>Support for low bandwidth connections.</strong> S3QL splits file contents into smaller blocks and caches blocks locally. This minimizes both the number of network transactions required for reading and writing data, and the amount of data that has to be transferred when only parts of a file are read or written. </li>    </ul>    <p>S3QL 1.7 改进内容：</p>    <ul>     <li>Metadata is now stored in a custom, delta-encoded binary format, and inodes are assigned sequentially and not reused. </li>     <li>This makes S3QL fully NFS-compatible. </li>     <li>s3qlcp now<span class="truncate_more"> also copies extended attributes and no longer generates incorrect block reference counts when copying a file which has identical blocks. <br /> </span></li>     <li><span class="truncate_more">This release eliminates a race condition in s3qlcp. <br /> </span></li>     <li><span class="truncate_more">When copying a file with s3qlcp immediately after it was modified or created, it was possible that s3qlcp would copy the new file attributes but the old data blocks.</span></li>    </ul>    <span style="font-weight:bold;">项目地址：</span>    <a style="font-weight:bold;" href="/misc/goto?guid=4958192052972938978" target="_blank">http://code.google.com/p/s3ql/</a>