[plug] to LVM2 or not to LVM2...

[Denis Brown]

At 12:47 PM 9/10/2009, Daniel Pittman wrote:

>Denis Brown <dsbrown at cyllene.uwa.edu.au> writes:

<snip>

> > An attraction with LVM2 is the ability to re-size partitions painlessly and
> > this can be important for a production database application which this is.
> > For example in the past I have opted for ext3 and manual partitioning.
> > After a while assumptions that seemed good at the time can turn out to be
> > less than ideal and re-partitioning can be a pain.
> >
> > The main question I have is "Where is the metadata stored, that defines a
> > logical group and its logical volumes?"  On the system drive?  On the LVM
> > itself?
>
>Yes.  LVM writes a metadata header to the physical volumes that identify their
>role in life.  It also maintains a backup of that metadata, elsewhere, so you
>can recover in the (pretty unlikely) event that it gets damaged.
>
> > Another way of looking at that is "What do I need to pay special attention
> > to, in backing up, in order not to lose this valuable metadata?"
>
>No more than you do for the partition table or MD software raid meta-data.
>(Which is to say, yes, your disaster recovery plan /should/ take that into
>  account, but you probably don't need to deal with this like you would, say,
>  the files under /etc.)
>
> > TNSTAAFL and this ability to shrink and grow logical volumes will have a
> > small performance penalty.  I can live with that in favour of the potential
> > flexibility.  But is this flexibility going to have a high price down the
> > track?
>
>No, not really.
>         Daniel

Thanks, Daniel.    Good to hear, so I guess I'll go that way.

Regards,
Denis