[PVFS2-developers] possible new config file options?

[Brad Settlemyer]

Distribution parameters can be set by name, so by specifying the dist
name and param name for the distribution in the config file, it would
possible for that to work for any distribution.  

That is what RobR and I had discussed, perhaps it is an extension of
Phil's system, where each dist can be customized, and then the default
dist can be selected (in its own section).

I think Phil's way of setting the number of dfiles is perhaps still
better tho -- though I also think that distributions still have the
right to ignore that hint if they so choose.  It leads to slightly
subtle behavior -- distributions may ignore server settings, but not
client hints . . . I don't know.  I think I lost the argument that the
distribution could ignore client hints, so maybe the dist can't ignore
server settings either.

Cheers,
Brad

On Thu, 2005-06-16 at 14:41 -0400, dhildebz at eecs.umich.edu wrote:
> Hello,
> If you guys are going to have a distribution section, why not provide support
> for each distribution to specify a list of variables that are specific to each
> distribution.   Maybe the PVFS2 code that reads in the name/value pairs can
> pass them (in a hashtable or something) to the distribution code.  I can
> imagine distributions that would like to be able to customize more parameters
> than just stripe size and # iods per file.
> 
> Dean
> Quoting Brad Settlemyer <bradles at parl.clemson.edu>:
> 
> > Hello
> >
> >   RobR and I were speaking about this yesterday.  I have no complaints
> > about what you're choices, though I would like to point out that the
> > number of dfiles selected is semi-dependent on the distribution -- that
> > is the distribution gets a shot to verload the value if it so chooses.
> > For that reason, we had kind of discussed making the default number of
> > dfiles a distribution setting:  (I don't know the config-file format, so
> > excuse any mistakes)
> > <distribution>
> >   <simple_stripe>
> > 	strip_size xxx
> > 	num_dfiles xxx
> >
> > You actually make a very good point that the number of dfiles is not an
> > explicit parameter to the distribution, but it is in fact set (even in
> > the simple_stripe case) by distribution code.
> >
> > Your way is probably still better tho, as simple stripe simply uses the
> > default dfile selecter, which chooses all I/O servers, custom
> > distributions would then still override that setting, and could provide
> > it as their own param as well if neccesary.
> >
> > So basically, I like how you've proposed it!
> >
> > (I'm also going to attempt to make the default number of dfiles client
> > configurable in the pvfs2tab -- with dists and hints still able to
> > overload the value, tho I haven't worked out how exactly quite yet)
> >
> > Cheers,
> > Brad
> >
> > On Thu, 2005-06-16 at 19:57 +0200, Phil Carns wrote:
> > > It seems like the server configuration files need a few more tunable
> > > options at this point.  David Metheny and I spent some time
> > > brainstorming and came up with the list below for high level parameters.
> > >   We didn't worry about flow/bmi/trove options.
> > >
> > > Any comments?
> > >
> >
> > > 2) default distribution type and parameters: On a per file system level,
> > > it would be nice to be able to chose the default distribution as well as
> > > arbitrary parameters to go with it.  There could be multiple "Param"
> > > keywords, and the strings following them will be given to distribution
> > > specific code to handle so that the conf parser doesn't have to be
> > > updated each time a distribution is added.
> > >
> > > <FileSystem>
> > > ...
> > > <DefaultDistribution>
> > > Name simple_stripe
> > > Param strip_size 65536
> > > </DefaultDistribution>
> > > </FileSystem>
> > >
> >
> > > 4) default number of datafiles: On a per file system basis, how many
> > > datafiles should be chosen per file.  The system interface would still
> > > be able to override this option:
> > >
> > > <FileSystem>
> > > ...
> > > DefaultNumDataFiles 4
> > > </FileSystem>
> > >
> >
> >
> > _______________________________________________
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> > PVFS2-developers at beowulf-underground.org
> > http://www.beowulf-underground.org/mailman/listinfo/pvfs2-developers
> >
> 
> 
> 
> 
>