[mythtv-users] Should I use LVM on this new raid?

Brian Foddy bfoddy at visi.com
Sat Sep 22 19:16:04 UTC 2007

On Saturday 22 September 2007, Michael Heironimus wrote:
> On Sat, Sep 22, 2007 at 11:32:33AM -0500, Brian Foddy wrote:
> > I'll look into it.  I'm starting to see some limitations to my
> > original thinking.  First, not sure LVM will allow me to expand the
> > physical volumes, which is I think what would be happening. There is a
> > lot more here than I expected....
> You're not supposed to expand LVM physical volumes, you create new ones
> and add them to the volume group. Make sure you create partitions on the
> array, don't pvcreate it as a whole disk. After expanding the array the
> disk (/dev/sda or whatever) should have free space at the end. You would
> create another partition in the new space, pvcreate it, and extend the
> volume group on to it.

Ok, this is key to my understanding...  It didn't seem logical to me that
a PV could be expanded.

As I see it, I can make the raid expandable as one /dev/sdb and then 
partition it with fdisk or whatever just like a normal HD.

Or I would tell the raid controller to limit the unit size to say 1TB,
and it would then break my 2 drives up a /dev/sdb and /dev/sdc.
Then attach a PV to each (or even smaller sections).

I've heard its more efficient to attach the LVM directly to the device
and not partition so the stripe size match up better (64KB)??  I maybe
be mangling the argument??


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