[linux-lvm] Shrinking a LVM physical volume

[linux-lvm] Shrinking a LVM physical volume

[Drew]

Hi there,

I have a system that I dual boot Windows and Debian from. Due to a
minor mistake on my part when carving out the space on my drive for my
linux partition, I now find myself with insufficient space on my
windows partition.

How do you shrink a physical volume on lvm? And then once that's done,
how safe is it to move the lvm partition around on the drive?

-- 
Drew

"Nothing in life is to be feared. It is only to be understood."
--Marie Curie

Re: [linux-lvm] Shrinking a LVM physical volume

[Lupe Christoph]

On Tuesday, 2009-03-24 at 07:59:09 -0700, Drew wrote:

> I have a system that I dual boot Windows and Debian from. Due to a
> minor mistake on my part when carving out the space on my drive for my
> linux partition, I now find myself with insufficient space on my
> windows partition.

> How do you shrink a physical volume on lvm?

Since nobody with real experience doing that has answered, I'll supply
my fewer than 2 Eurocents...

According to its manpage, it should be safe to use
  pvresize --setphysicalvolumesize <newsize> <pvdevice>
prior to resizing the partition. It should complain if there are extents
in use beyond <newsize>.

I say "it should" because I never tried it. So make a backup, blahblah,
etcetera...

> And then once that's done,
> how safe is it to move the lvm partition around on the drive?

That is up to somebody with more knowledge to answer.

HTH,
Lupe Christoph
-- 
| There is no substitute for bad design except worse design.                   |
| /me                                                                          |

Re: [linux-lvm] Shrinking a LVM physical volume

[Brian McCullough]

On Tue, Mar 24, 2009 at 10:54:10PM +0100, Lupe Christoph wrote:
> On Tuesday, 2009-03-24 at 07:59:09 -0700, Drew wrote:
> 
> > I have a system that I dual boot Windows and Debian from. Due to a
> > minor mistake on my part when carving out the space on my drive for my
> > linux partition, I now find myself with insufficient space on my
> > windows partition.
> 
> > How do you shrink a physical volume on lvm?
> 
> Since nobody with real experience doing that has answered, I'll supply
> my fewer than 2 Eurocents...


Good answer, Lupe.

One other thing to be aware of;  you should know the amount of space 
that has been allocated within the Physical Volume.  If that amount 
exceeds the amount that you wish to recover, you may be able to
shrink Logical Volumes within the Physical Volume, but, of course,
before doing so, you should shrink the filesystems that are contained
within the logical volumes.



Have fun!
Brian

[linux-lvm] Re: Shrinking a LVM physical volume

[Stefan Monnier]

> According to its manpage, it should be safe to use
>   pvresize --setphysicalvolumesize <newsize> <pvdevice>
> prior to resizing the partition. It should complain if there are extents
> in use beyond <newsize>.

Is there some way to move those extents?
I guess there's pvmove, but that seems to only be able to move them to
some other PV.

>> And then once that's done,
>> how safe is it to move the lvm partition around on the drive?
> That is up to somebody with more knowledge to answer.

I can confirm that PVs can be moved at will (even between drives).
I've done it a few times.


        Stefan