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Supported Features

• Basic POSIX file system features
• Snapshots
  • Automatically and continuously taken, you can retrieve past state of NILFS file system.
  • No limit on the number of snapshots until the volume gets full
  • Mountable as read-only file systems
  • Simultaneously mountable
  • Mountable concurrently with the writable mount (convenient for online backup)
  • Quick listing
  • Easy administration
• Online disk space reclamation
  • Can maintain multiple snapshots
  • Selectable GC Policy, which is given by a userland daemon.
• Quick crash recovery on-mount
• Less use of barrier with keeping reliability; barrier is enabled by default.
• Read-ahead for meta data files as well as data files
• Block sizes smaller than page size (e.g. 1KB or 2KB)
• Redundant super block
• Related utilities (by contribution of Jiro SEKIBA)
  • grub2
  • util-linux-ng (blkid, libblkid, uuid mount)
  • udisks, palimpsest

TODO List

• Filesystem label (work in progress)
• parted (work in progress)
• Checkpoint rollback
• Checkpoint based remote replication
• Performance improvement (Better Block I/O submission)
• Extended attribute
• POSIX ACLs
• Quota
• atime
• Optimization for silicon disks (e.g. SSD)
• fsck
• Faster inode allocation
• Online resizing
• Online defrag
• Shred file along with its past versions
• filesystem freeze
• Variety of Garbage Collection policies
• Design document and better developer support
• Better support of fsync, mmap, and direct I/O.
• Unified user command ``nilfs'' (rather than separate commands like lscp, rmcp, mkcp, etc).
• "Time-based" tools (e.g. tls, tdiff, tgrep, tfind, ttar and so on. They come from the Elephant file system)
• Time-machine like browser.
• Time slider

Long term TODO list:

• Writable snapshots
• Snapshot tagging
• Quota support
• B-tree based directory management
• Extent support