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SubjectRe: Implementing Meta File information in Linux (and a note at the end on current reiserfs status)
Vladimir Dergachev wrote:

> > I don't know anything about RMS, but ORACLE uses raw disk for a reason..... To
> > avoid letting layering give you the worst performance aspects of two storage models
> > combined.
> >
>
> I think there is a good point here. My impression was that so far the
> discussion focused on how are we going to implement "Meta stuff" instead
> of what it is supposed to, what problem it solves.
>
> My formulation is that with introduction of the GUI we _have_ to deal with
> databases. In fact, /etc/passwd is nothing else but a database, though
> one wasn't concerned very much with perfomance of it. GUI stuff is
> different. There are multitude of settings which are kept in separate
> files in different formats. In the process of using GUI (especially X)
> the applications impose a severe load on the system. What is more nothing
> is used effeciently - the time is spent doing stat calls, reading small
> files randomlly of disk and parsing them.
>
> This is not helped by (a reasonable) insistance of programmers on ASCII
> configuration files.
>
> Thus the solution to this problem should be a "database filesystem"
> optimized for quick access to small parts of data and a lot of
> crossreference between it.

This is what ReiserFS is intended to be. Over the next 15 yearsI will add more and more database features to it, right now all it has
is efficient indexes (directories) and efficient packing of small files.
The rest will come with time.

>
>
> This filesystem could be either contained in a separate partition or
> looped back on a file.
>
> A more exotic (and probably more efficient) way would be to put it in the
> "end" of ext2 filesystem so that both could grow if needs be. This
> integration could also have other benifits.
>
> In other words there is a difference between a plain file (read continuous
> chunk of infomation like binary,tex file or c code) and database file with
> records in it. The latter should be treated specifically in order to
> optimize perfomance.

Yes, and I think your needs are met if that database file is made into a directory,
and the FS implements directories well.
In time ReiserFS will offer you more and more sophisticated directories, but
for now we offer something fairly effective for these needs.

>
>
> One could also envision the file itself being associated with database
> entries. In this context the copying of the file will copy the entries
> as well. If one would attempt to copy the file outside of ext2 that should
> produce those ".fork" database files.

Why not just put the file in the same directory as the database entries?

In time more and more sophisticated ways of associating will be supported
by ReiserFS......

Best Regards,

Hans



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