[Linux-cluster] Gfs_data vs gfs_journal

[Cahill, Ben M]

Yes, you're correct ... however, the idea in OpenGFS was to not rely on
pool, but to allow other "generic" volume managers to be used instead.

-- Ben --

Opinions are mine, not Intel's

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com 
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Erling Nygaard
> Sent: Wednesday, July 07, 2004 12:21 PM
> To: Discussion of clustering software components including GFS
> Subject: Re: [Linux-cluster] Gfs_data vs gfs_journal
> 
> Ben
> 
> You can indeed have external journals with GFS.
> 
> As Mike was saying, you can specify a subpool with type "gfs_journal".
> And since you easily can specify what device the subpool is 
> on you decide 
> where the journal is.
> 
> This feature has been in GFS since 'a looong time ago' and 
> unless there 
> have been changes to this in OpenGFS this feature works in 
> the same way in 
> all versions of GFS :)
> 
> As Mike pointed out, this was originally done in case of Solid State 
> Disks, where having the journals on the SSD could prove 
> speedup. Due to 
> lack of SSDs this has never really been tested much...
> 
> 
> Erling
> 
> 
> 
> On Wed, Jul 07, 2004 at 08:16:59AM -0700, Cahill, Ben M wrote:
> > Oops, based on Michael's response, I realized that mine might be not
> > quite right.  Both data and journal *space* are necessary, but the
> > journals can be created, by default, within the filesystem 
> device, with
> > no need for gfs_journal entry in config file.
> > 
> > BTW, OpenGFS has supported external journals for over a year at this
> > point ... would this be a useful feature for GFS?
> > 
> > -- Ben --
> > 
> > Opinions are mine, not Intel's
> > 
> > > -----Original Message-----
> > > From: linux-cluster-bounces at redhat.com 
> > > [mailto:linux-cluster-bounces at redhat.com] On Behalf Of 
> Cahill, Ben M
> > > Sent: Wednesday, July 07, 2004 11:07 AM
> > > To: linux-cluster at redhat.com
> > > Subject: RE: [Linux-cluster] Gfs_data vs gfs_journal
> > > 
> > > They are both necessary.
> > > 
> > > gfs_data is the device/partition for filesystem data 
> (i.e. files and
> > > on-disk metadata).
> > > 
> > > Each node in the cluster also needs a separate journal 
> > > device/partition
> > > in which to redundantly record metadata, to enable the 
> filesystem to
> > > recover gracefully from node failure/crash.
> > > 
> > > There's some documentation about this in the OpenGFS project:
> > > 
> > > opengfs.sourceforge.net/docs.php
> > > 
> > > CAUTION:  OpenGFS is *not* the same as current RedHat 
> GFS; many things
> > > (e.g. lock protocols) are different ... but the basic idea is 
> > > the same.
> > > See WHATIS-OpenGFS, and HOWTO-generic, just to see if 
> they help you
> > > understand.  But remember to rely on current RedHat GFS docs 
> > > for current
> > > installation, components, and capabilities info.
> > > 
> > > -- Ben --
> > > 
> > > Opinions are mine, not Intel's
> > > 
> > > > -----Original Message-----
> > > > From: linux-cluster-bounces at redhat.com 
> > > > [mailto:linux-cluster-bounces at redhat.com] On Behalf Of 
> > > Richard Mayhew
> > > > Sent: Wednesday, July 07, 2004 6:24 AM
> > > > To: Discussion of clustering software components including GFS
> > > > Subject: [Linux-cluster] Gfs_data vs gfs_journal
> > > > 
> > > > Hi,
> > > > 
> > > > 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?
> > > > 
> > > > Thanks
> > > > Richard.
> > > > 
> > > > --
> > > > Linux-cluster mailing list
> > > > Linux-cluster at redhat.com
> > > > http://www.redhat.com/mailman/listinfo/linux-cluster
> > > > 
> > > > 
> > > 
> > > --
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> > > 
> > > 
> > 
> > --
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> 
> -- 
> Erling Nygaard
> nygaard at redhat.com
> 
> Red Hat Inc
> 
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