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Hi,Yesterday I played a bit with NILFS2 on ubuntu 11.04. It was quite easy to use, but finding previous versions of a file is still a bit complicated from a user point of view.
I read a bit about ext3cow, which is currently not actively maintained anymore. In one of the papers on ext3cow, I read the following:
Other disk file systems provide coarse-grained access to versions throughthe creation of namespace tunnels [Hitz et al. 1994] or via mounting separate logical volumes [Strunk et al. 2000; Soules et al. 2003]. Some disk file systems provide no interface to versions, restricting versioning to internal use only [Rosenblum and Ousterhout 1992;
Seltzer et al. 1993].In time-shifting, ext3cow introduces an interface to versioning that presents a continuous view of time. Users or applications specify a file name and any point in time, which ext3cow scopes to the appropriate snapshot or file version. The time-shifting interface
allows user-space tools to create snapshots and access versions. Ext3cow: A Time-Shifting File System for Regulatory Compliance ZACHARY N. J. PETERSON and RANDAL BURNS ACM Transactions on Storage, 1(2), May, 2005 http://www.ext3cow.com/ext3cow/Publications.html A usage scenario is given in a screenshot: http://www.ext3cow.com/ext3cow/Welcome_files/example1.jpgI don't think using the "@" symbol for such thinks is a great idea (I sometimes use it in my filenames) but the ability to use regular tools to access old versions of files is great.
I think it would be really useful to have access to previous versions of files without having to go through checkpoints or snapshots of the whole filesystem / partition. So having something like lshistory or lsversions for specific files would be great. It could output the versions, the checkpoints where those versions are available, etc. Maybe direct retrieval of old versions (cathistory?) could also be possible using such a path.
Of course the architecture of NILFS is different from ext3cow so I don't know whether this is even possible. Something like a data structure linking the different verions of some inode must exist before this can happen. Just an idea, though.
Thanks for your cool stuff! Evert -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html