Re: FileSystem Question

On Fri, Jun 29, 2007 at 06:45:03PM +0000, Manon Metten wrote:


It's definitely no ordinary backup or RAID. It even works with a single hd.
SFS takes care of all this. I don't have to backup anything. SFS just
writes all subsequent copies of a file to different locations on the hd and
moves the existing ones to .recycled (well, in fact it only updates the
TOC). .recycled is just a hidden directory where all previous copies of a
file are stored.

This also means that in the rare case of a system crash when saving a
file, I only lose that part of my work that was in memory only. The copy
on disk remains untouched because only AFTER a new copy is written
to disk (to a different location), the old copy will be moved to .recycled
and the TOC will be updated. But in case of a crash during save, the
new copy isn't finished and thus the old copy remains untouched and
no TOC update is necessary. This whole process is completely hidden
for the user. .recycled only comes to mind when I have to recover some
data.

It sounds like the Log File System (LFS) that NetBSD is working on, or
the database-style of a mainframe where every 'file' is really a record
in a database where back copies are maintained until the space is
needed.

I haven't seen anything like this in Linux.

There was one application where I needed this and it implemented it with
a postgresql database with the files being 'huge' objects.

I've never used it but you can probably use a CVS repository for this
more conveniently.

Doug.


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Relevant Pages

  • Re: FileSystem Question
    ... SFS takes care of all this. ... to disk, the old copy will be moved to .recycled ... and the TOC will be updated. ... the database-style of a mainframe where every 'file' is really a record ...
    (Debian-User)
  • Re: Robust single file database
    ... database novice). ... It may also invite users to put their own stuff into those folders, ... I have just found out that SFS performance suffers if you ... write lots of small pieces to a stream, rather than write the whole stream ...
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