On Wed, 20 Aug 2008 11:45:05 +0900 Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx> wrote: > This is a kernel patch of NILFS2 file system which was previously > announced in [1]. Since the original code did not comply with the > Linux Coding Style, I've rewritten it a lot. I expected this email two years ago :) > NILFS2 is a log-structured file system (LFS) supporting ``continuous > snapshotting''. In addition to versioning capability of the entire > file system, users can even restore files and namespaces mistakenly > overwritten or destroyed just a few seconds ago. > > NILFS2 creates a number of checkpoints every few seconds or per > synchronous write basis (unless there is no change). Users can select > significant versions among continuously created checkpoints, and can > change them into snapshots which will be preserved until they are > changed back to checkpoints. What approach does it take to garbage collection? > There is no limit on the number of snapshots until the volume gets > full. Each snapshot is mountable as a read-only file system > concurrently with its writable mount, and this feature is convenient > for online backup. It will be also favorable for time-machine like > user environment or appliances. > > Please see [2] for details on the project. > > Other features are: > > - Quick crash recovery on-mount (like conventional LFS) > - B-tree based file, inode, and other meta data management including > snapshots. > - 64-bit data structures; support many files, large files and disks. > - Online disk space reclamation by userland daemon, which can maintain > multiple snapshots. > - Less use of barrier with keeping reliability. The barrier is enabled > by default. > - Easy and quickly performable snapshot administration > > Some impressive benchmark results on SSD are shown in [3], heh. It wipes the floor with everything, including btrfs. But a log-based fs will do that, initially. What will the performace look like after a month or two's usage? > however the > current NILFS2 performance is sensitive to machine environment due to > its immature implementation. > > It has many TODO items: > > - performance improvement (better block I/O submission) > - better integration of b-tree node cache with filemap and buffer code. > - cleanups, further simplification. > - atime support > - extendend attributes support > - POSIX ACL support > - Quota support > > The patch against 2.6.27-rc3 (hopefully applicable to the next -mm > tree) is available at: > > http://www.nilfs.org/pub/patch/nilfs2-continuous-snapshotting-file-system.patch Needs a few fixes for recent linux-next changes. I queued it up without looking at it, just for a bit of review and compile-coverage testing. > It is not yet divided into pieces (sorry). Unlike original code > available at [4], many code lines to support past kernel versions and > peculiar debug code are removed in this patch. Yes, please do that splitup and let's get down to reviewing it. > The userland tools are included in nilfs-utils package, which is > available from [4]. Details on the tools are described in the man > pages included in the package. > > Here is an example: > > - To use nilfs2 as a local file system, simply: > > # mkfs -t nilfs2 /dev/block_device > # mount -t nilfs2 /dev/block_device /dir > > This will also invoke the cleaner through the mount helper program > (mount.nilfs2). > > - Checkpoints and snapshots are managed by the following commands. > Their manpages are included in the nilfs-utils package above. > > lscp list checkpoints or snapshots. > mkcp make a checkpoint or a snapshot. > chcp change an existing checkpoint to a snapshot or vice versa. > rmcp invalidate specified checkpoint(s). > > For example, > > # chcp ss 2 > > changes the checkpoint No. 2 into snapshot. > > - To mount a snapshot, > > # mount -t nilfs2 -r -o cp=<cno> /dev/block_device /snap_dir > > where <cno> is the checkpoint number of the snapshot. > > - More illustrative example is found in [5]. > > Thank you, > Ryusuke Konishi, NILFS Team, NTT. > > 1. NILFS version2 now available > http://marc.info/?l=linux-fsdevel&m=118187597808509&w=2 > > 2. NILFS homepage > http://www.nilfs.org/en/index.html > > 3. Dongjun Shin, About SSD > http://www.usenix.org/event/lsf08/tech/shin_SSD.pdf Interesting document, that. > 4. Source archive > http://www.nilfs.org/en/download.html > > 5. Using NILFS > http://www.nilfs.org/en/about_nilfs.html -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
