ext3cow

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ext3cow
Developer Zachary Peterson (ext3cow versioning), Stephen Tweedie (ext3 design and implementation), Rémy Card (original ext2 design and implementation), Theodore Ts'o (tools and improvements), Andreas Gruenbacher (xattrs and ACLs), Andreas Dilger (online resizing), et al.
Full name Third extended file system with copy-on-write
Introduced July 2003 (Linux)
Partition identifier 0x83 (MBR)
EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 (GPT)
Structures
Directory contents Table, Tree
File allocation bitmap (free space), table (metadata)
Bad blocks Table
Limits
Max. volume size 8TiB
Max. file size 2TiB
Max. number of files Variable1
Max. filename length 255 bytes
Allowed characters in filenames All bytes except NUL, '/' and '@'
Features
Dates recorded modification (mtime), attribute modification (ctime), access (atime)
Date range December 14, 1901 - January 18, 2038
Date resolution 1s
Forks Yes
Attributes No-atime, append-only, synchronous-write, no-dump, h-tree (directory), immutable, journal, secure-delete, top (directory), allow-undelete
File system permissions Unix permissions, ACLs and arbitrary security attributes (Linux 2.6 and later)
Transparent compression No
Transparent encryption No (provided at the block device level)
Other
Supported operating systems Linux

Ext3cow or third extended filesystem with copy-on-write is an open source, versioning file system based on the ext3 file system. Versioning is implemented through block-level copy-on-write. It shares many of its performance characteristics with ext3.

Ext3cow provides a time-shifting interface that permits a real-time and continuous view of data in the past. Time-shifting is a novel interface, introduced in ext3cow, allowing users to navigate through and access past namespaces by adding a time component to their commands.

Ext3cow was designed to be a platform for compliance with the versioning and auditability requirements of recent US electronic record retention legislation, such as Sarbanes-Oxley and HIPAA.

A version of ext3cow for the Linux 2.6 kernel was released on March 30, 2007.

Details on ext3cow's implementation can be found in a 2005 paper.[1]

See also[edit]

References[edit]

  1. ^ Zachary Peterson and Randal Burns (May 2005). "Ext3cow: A Time-Shifting File System for Regulatory Compliance" (PDF). ACM Transactions on Storage, 1(2). 

External links[edit]