Hibernate with LVM Swap

[Peter Jones]

On Mon, 2006-06-12 at 19:51 -0600, Lamont R. Peterson wrote:

> So, Peter, are you saying that using up 3 partitions is so bad compared to 2 
> that we should be concerned about it?

Yes, absolutely.  That being said, the economy of partitions themselves
isn't the only advantage.  What if you wanted to make your swap device
*smaller*, and give the freed space up to some already extant
filesystem?  If it's not on LVM, you really can't do that.

Really, it's this simple: if you're going to have LVM for anything, you
want to use it wherever it's possible on your persistently attached
storage.  For us, right now, that means everything except /boot .

> Sorry, this is a non-starter argument to me.

Consider dual booting and other such scenarios.

> I'm saying that LVM has several very worthwhile benefits and that non of them 
> matter when it comes to swap and that since LVM doesn't benefit swap, it 
> doesn't make sense to put swap on LVM.

That's just not right.  It's worth doing it if for no other reason than
conserving partitions.

> The only exception I see is the example of needing 30GB of RAM to do some big, 
> one-time operation.  In that case, sure, create an extra swap LV and use it, 
> removing it when you're done.

In that scenario, paging out to swap at all is almost certainly
something you want never to happen.  But these days, that's true most of
the time anyway.

Moreover, there isn't a compelling reason *not* to do it.  This
hypothetical performance-while-swapping argument you've got just isn't
reality.  You're not CPU bound when you're swapping.  You're I/O
limited, and most of the limit isn't time on the host bus, it's disk
seeks.  I really doubt if LVM will make any significant difference --
measurable difference, that is, much less noticeable by a human -- at
all.

-- 
  Peter