[Linux-cluster] Gfs_data vs gfs_journal

[Michael Conrad Tadpol Tilstra]

On Wed, Jul 07, 2004 at 12:23:41PM +0200, Richard Mayhew wrote:
> Could some one explain or point me in the right direction in the
> differences between gfs_data and gfs_journal in the pool config file.
> 
> Which is the better option, and why?

For nearly everyone, just use gfs_data.
gfs_journal is for controling where physically gfs puts the journals.
(file system data goes in gfs_data, journals in gfs_journal.)

The idea when we originally made this was that someon might have a
really fast but small storage device, and then a bunch of more common
storage.  They then could use pool to combine the two devices into a
single pool, putting the journal onto the faster device. Which then, in
theory, would make gfs faster.  I don't think it has ever been tested
though.  You have to tell mkfs.gfs to look at pool lables to use this.
(I forget the cmd option, its in the man page.)

If you don't tell mkfs.gfs to look at pool labels, the labels are
ignored.  And gfs puts the journals in the middle of the data section I
think. (could be wrong on that.)

Hope that helps.
-- 
Michael Conrad Tadpol Tilstra
I hate when they fix a bug that I use.
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