[Linux-cluster] A few GFS newbie questions: journals, etc

[JACOB_LIBERMAN at Dell.com]

Jason,

LVM2 has a vgextend command that can be used to add a new PV to a vg.
There is also an lvextend and ext2online so you can increase the size of
the lv without dismounting it. This is slightly different than a
pvextend, but I believe it achieves the same end result.

So a process you might be able to try is:

1. extend the LUN on the SAN
2. use fdisk to create a new partition on the LUN
3. use partprobe -s to dynamically redetect the new partition
4. make a new filesystem on the partition
5. use vgextend to add the new PV to the VG
6. use lvextend to add new space to the LV
7. use ext2online of gfs_grow to tarck out the filesystem on the new
space *without* dismounting or rebooting

I've used to above procedure under RHEL4 with LVM2 and an ext3
filesystem. I have not tried it w/GFS yet because our reference lab is
down for maintenance.

Thanks, jacob

> -----Original Message-----
> From: linux-cluster-bounces at redhat.com 
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Jason Lanclos
> Sent: Tuesday, July 05, 2005 10:52 PM
> To: linux clustering
> Subject: Re: [Linux-cluster] A few GFS newbie questions: journals, etc
> 
> 
> > > You shouldn't even need CLVM if you don't intend to muddle with 
> > > partitions or cross-mount the file systems.  You'll lose 
> resizing, 
> > > but in doing so, your clients no longer need to be 
> cluster participants.
> >
> 
> CLVM is cool, but its pretty much useless until LVM2 actually 
> implements pvresize or a pvextend. One of the main advantages 
> of having a SAN is being 
> able to add space to a volume (LUN)   Currently when we 
> expand a volume on 
> the san, we have to unmount the filesystem, rescan the LUNs, 
> then run fdisk on that volume, delete the partition entry, 
> and recreate it to use all the space.. then at that point we 
> can run ext2online / gfs_grow to resize the filesystem.
> 
> I would be VERY nice if pvresize / pvextend existed, that way 
> one could expand the volume on the SAN, rescan LUNs on each 
> cluster member, run pvresize / pvextend, run lvextend and 
> then gfs_grow and call it a day.
> 
> I mentioned this at the RedHat summit, and got a few puzzled 
> looks, but never got an answer on the matter.
> 
> 
> 
> > Oh certainly...
> >
> > I was just trying to think of why someone would want to use 
> GFS to do
> > this, and the idea of the machines not have pre-fixed 
> partition sizes was
> > about the only thing I could think of.
> >
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