gjournal....

[Karl Denninger]

On Sun, Mar 30, 2008 at 02:06:17AM -0700, Alfred Perlstein wrote:
> * Karl Denninger <karl at denninger.net> [080329 20:10] wrote:
> > Hi folks;
> > 
> > Wondering about the various pros and cons of using the "gjournal" GEOM
> > provider... and if you can "promote" and existing system using it, or
> > whether you need to build something anew.
> > 
> > The scenario is a fairly busy and large system with PostgreSQL database data
> > on it.  The data is currently on a 2-disk gmirror pair to provide data
> > safety in the event of a disk failure.
> > 
> > I am using softupdates right now.
> > 
> > If I'm reading the docs correctly, I can't put gjournal in use on the
> > existing filesystem, and need to effectively build a new disk structure then
> > copy over the data onto it.
> > 
> > Can you boot from a gjournal'd root? 
> > 
> > Ideas please, pros and cons of the various alternatives, etc..... thanks!
> > 
> 
> If you're using a database then it shouldn't matter what meta data
> provider you use "all that much" with the exception of temporary
> tables.
> 
> Basically, SU and gjournal both provide for meta data consistency,
> something that a database rarely needs as it rarely creates/deletes
> files often.
> 

I'm looking at this more from a performance standpoint.

Is there a performance advantage to using gjournal over a "normal" UFS/UFS2
filesystem with softupdates?

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