[Mulgara-general] Spanning multiple disks

[Chuck Borromeo]

As far as I know this is not a problem right now.  I am still evaluating Mulgara so I have not really hit any performance issues yet.  (I was using Virtuoso to store triple data and now I am looking at Mulgara.)  Could it be possible to add the ability to span multiple disks into the list of features for the new file system?  I have read some of the documents concerning the XA2 file system.  If XA2 is meant to scale to really large data sets (on the order of TB), I think I/O will quickly become an issue.

I have a second question (and this is probably a simple one), how do I start Mulgara to use more java virtual memory?  I try running Mulgara from the command line with these parameters:

java -Xmx1024m -jar mulgara-2.0-alpha.jar -p 4567

I get java.IO.FileException: Cannot Allocate memory error at MappedIntFile.mapFile.  I have been trying to load a fairly large set of data into Mulgara and I get java heap memory errors.  I was hoping to extend the heap memory of Mulgara to avoid the errors while loading.   Any suggestions?

Thanks for your hard work (and the SPARQL classes)
Chuck


--- On Mon, 6/30/08, Paul Gearon <gearon at ieee.org> wrote:

> From: Paul Gearon <gearon at ieee.org>
> Subject: Re: [Mulgara-general] Spanning multiple disks
> To: cborromeo3 at yahoo.com, "Mulgara General" <mulgara-general at mulgara.org>
> Date: Monday, June 30, 2008, 11:07 AM
> On Mon, Jun 30, 2008 at 9:47 AM, Chuck Borromeo
> <cborromeo3 at yahoo.com> wrote:
> > Hello,
> >  Can Mulgara support spanning its data directories
> (xaStatementStore, xaStringPool, etc.) across multiple
> disks?  I am concerned that having all my data on one disk
> will result in my queries becoming I/O bound.  If it can
> support this, is there a suggested methodology for
> splitting up the directories across multiple disks?  I am
> using the Mulgara 2.0 alpha release.
> 
> Unfortunately, no, and you're right.... it does create
> an I/O problem.
> 
> We were planning on doing this (it's really just a
> matter of
> configuration), but put it off since we are in the process
> of building
> a new filesystem structure.  If there is real call for it,
> then I'm
> sure I can convince my boss to let me have the time for it,
> as it
> should only take a couple of days to get it done.
> 
> Paul