Resizing physical volume for lvm.
 

On Sunday 22 March 2009 22:15:14 Momesso Andrea wrote:
> My current setup is:
>
> Device Boot Start End Blocks Id System
> /dev/sda1 * 1 2894 23246023+ 83 Linux
> /dev/sda2 2895 3381 3911827+ 82 Linux
> swap /Solaris
> /dev/sda3 3382 24804 172080247+ 83 Linux
> /dev/sda4 24805 30401 44957902+ 83 Linux
>
> where sda3 is an lvm volume and sda4 is free space.
>
> I'd like to to merge sda3 and sda4 into a single partition without
> losing the data on it, but I'm not sure if it is possible.
>
> My guess is that I can use fdisk to delete sda4 and sda3, create a sda3
> partition starting at 3382 and ending at 30401, then use pvresize to
> enlarge it.

Correct. That's all there is to it.

> This is from man pvresize:
> "Expand the PV on /dev/sda1 after enlarging the partition with fdisk:
> pvresize /dev/sda1"
>
> Is that going to work or I'm going to lose all the data?

Your data is safe if you do exactly the steps you said above.

Caveat: I have no idea why this doesn't work, but if you make sda4 an extended
partition and create sda5 as a logical with exactly the same start and end as
you describe above, you do in fact lose all data. Obviously there is a
difference between a physical and a logical partition with the same location,
but I don't know why this is.

Which is a pity, as 4 logical partitions is a little too constrictive, I
prefer the extra freedom to move things around with extended partitions.

> P.S. I'm not using vgextend to simply add sda4 to the lvm because I
> might want to migrate my root (sda1) to ext4, and to do so I will need
> to split it in two separate partitions (/boot using ext3 and / using
> ext4). This way I'm not going to need extended partitions.

ext3 on /boot is pointless. The ext3 metadata takes up a considerable chunk of
the space on a typical /boot, for no good reason at all - writes to it are
exceptionally rare so there's no real-worlld benefit to the journal.

Ext2 is ideal for /boot.


--
alan dot mckinnon at gmail dot com

Resizing physical volume for lvm.
 

Am Sonntag, 22. März 2009 21:15:14 schrieb Momesso Andrea:
> P.S. I'm not using vgextend to simply add sda4 to the lvm because I
> might want to migrate my root (sda1) to ext4

Why do want to do that? ext4 is just a couple of months old and there's no
proof of stability whatsoever for it. Better try it with uncritical data
partitions (portage tree, distfiles) first.

Bye...

Dirk

Resizing physical volume for lvm.
 

On Sun, 22 Mar 2009 22:35:35 +0200
Alan McKinnon <alan.mckinnon@gmail.com> wrote:

> On Sunday 22 March 2009 22:15:14 Momesso Andrea wrote:
> > My current setup is:
> >
> > Device Boot Start End Blocks Id System
> > /dev/sda1 * 1 2894 23246023+ 83 Linux
> > /dev/sda2 2895 3381 3911827+ 82 Linux
> > swap /Solaris
> > /dev/sda3 3382 24804 172080247+ 83 Linux
> > /dev/sda4 24805 30401 44957902+ 83 Linux
> >
> > where sda3 is an lvm volume and sda4 is free space.
> >
> > I'd like to to merge sda3 and sda4 into a single partition without
> > losing the data on it, but I'm not sure if it is possible.
> >
> > My guess is that I can use fdisk to delete sda4 and sda3, create a
> > sda3 partition starting at 3382 and ending at 30401, then use
> > pvresize to enlarge it.
>
> Correct. That's all there is to it.
>
> > This is from man pvresize:
> > "Expand the PV on /dev/sda1 after enlarging the partition with
> > fdisk: pvresize /dev/sda1"
> >
> > Is that going to work or I'm going to lose all the data?
>
> Your data is safe if you do exactly the steps you said above.

Good to know! In any case backups are available, but I prefer not to
use them if not necessary.

>
> Caveat: I have no idea why this doesn't work, but if you make sda4 an
> extended partition and create sda5 as a logical with exactly the same
> start and end as you describe above, you do in fact lose all data.
> Obviously there is a difference between a physical and a logical
> partition with the same location, but I don't know why this is.
>
> Which is a pity, as 4 logical partitions is a little too
> constrictive, I prefer the extra freedom to move things around with
> extended partitions.
>
> > P.S. I'm not using vgextend to simply add sda4 to the lvm because I
> > might want to migrate my root (sda1) to ext4, and to do so I will
> > need to split it in two separate partitions (/boot using ext3 and /
> > using ext4). This way I'm not going to need extended partitions.
>
> ext3 on /boot is pointless. The ext3 metadata takes up a considerable
> chunk of the space on a typical /boot, for no good reason at all -
> writes to it are exceptionally rare so there's no real-worlld benefit
> to the journal.
>
> Ext2 is ideal for /boot.
>
Thanks for the advice. Will be a problem for lvm if I add a partition
before it? I mean, will I need to change any config files while lvm is
gonna reside on sda4 instead of sda3?

---
TopperH
http://topperh.blogspot.com

Resizing physical volume for lvm.
 

On Sun, 22 Mar 2009 21:39:29 +0100
Dirk Heinrichs <dirk.heinrichs@online.de> wrote:

> Am Sonntag, 22. März 2009 21:15:14 schrieb Momesso Andrea:
> > P.S. I'm not using vgextend to simply add sda4 to the lvm because I
> > might want to migrate my root (sda1) to ext4
>
> Why do want to do that? ext4 is just a couple of months old and
> there's no proof of stability whatsoever for it. Better try it with
> uncritical data partitions (portage tree, distfiles) first.
>
> Bye...
>
> Dirk

Don't want to do that right now, but I like to have things set up to
create me less problems as possible when I will decide to do the
migration.

In any case I don't consider the root partition of my laptop to be
really critical. I'm not planning any migration in /home, that will
remain ext3.

---
TopperH
http://topperh.blogspot.com

Resizing physical volume for lvm.
 

On Sun, 22 Mar 2009 21:39:29 +0100, Dirk Heinrichs wrote:

> > P.S. I'm not using vgextend to simply add sda4 to the lvm because I
> > might want to migrate my root (sda1) to ext4
>
> Why do want to do that? ext4 is just a couple of months old and there's
> no proof of stability whatsoever for it. Better try it with uncritical
> data partitions (portage tree, distfiles) first.

Yet if you do, the latest GRUB boots from ext4 partitions, so you don't
need to separate /boot.


--
Neil Bothwick

"I'm Not Sure If I'm Homosexual", Said Tom, Half In Earnest.

Resizing physical volume for lvm.
 

On Sun, 22 Mar 2009 20:49:36 +0000
Neil Bothwick <neil@digimed.co.uk> wrote:

> On Sun, 22 Mar 2009 21:39:29 +0100, Dirk Heinrichs wrote:
>
> > > P.S. I'm not using vgextend to simply add sda4 to the lvm because
> > > I might want to migrate my root (sda1) to ext4
> >
> > Why do want to do that? ext4 is just a couple of months old and
> > there's no proof of stability whatsoever for it. Better try it with
> > uncritical data partitions (portage tree, distfiles) first.
>
> Yet if you do, the latest GRUB boots from ext4 partitions, so you
> don't need to separate /boot.
>
>

I heard it can boot from ext4 using a patch that is not 100% safe...
Does anyone have positive (or negative) experience with that?

---
TopperH
http://topperh.blogspot.com

Resizing physical volume for lvm.
 

On Sun, 22 Mar 2009 22:35:35 +0200
Alan McKinnon <alan.mckinnon@gmail.com> wrote:

> On Sunday 22 March 2009 22:15:14 Momesso Andrea wrote:
> > My current setup is:
> >
> > Device Boot Start End Blocks Id System
> > /dev/sda1 * 1 2894 23246023+ 83 Linux
> > /dev/sda2 2895 3381 3911827+ 82 Linux
> > swap /Solaris
> > /dev/sda3 3382 24804 172080247+ 83 Linux
> > /dev/sda4 24805 30401 44957902+ 83 Linux
> >
> > where sda3 is an lvm volume and sda4 is free space.
> >
> > I'd like to to merge sda3 and sda4 into a single partition without
> > losing the data on it, but I'm not sure if it is possible.
> >
> > My guess is that I can use fdisk to delete sda4 and sda3, create a
> > sda3 partition starting at 3382 and ending at 30401, then use
> > pvresize to enlarge it.
>
> Correct. That's all there is to it.
>
> > This is from man pvresize:
> > "Expand the PV on /dev/sda1 after enlarging the partition with
> > fdisk: pvresize /dev/sda1"
> >
> > Is that going to work or I'm going to lose all the data?
>
> Your data is safe if you do exactly the steps you said above.
>
pvresize /dev/sda3
/dev/sda3: too many metadata areas for pvresize

Looks like I cannot expand it...

---
TopperH
http://topperh.blogspot.com

Resizing physical volume for lvm.
 

On Sun, 2009-03-22 at 21:58 +0100, Momesso Andrea wrote:
> On Sun, 22 Mar 2009 20:49:36 +0000
> Neil Bothwick <neil@digimed.co.uk> wrote:
>
> > On Sun, 22 Mar 2009 21:39:29 +0100, Dirk Heinrichs wrote:
> >
> > > > P.S. I'm not using vgextend to simply add sda4 to the lvm because
> > > > I might want to migrate my root (sda1) to ext4
> > >
> > > Why do want to do that? ext4 is just a couple of months old and
> > > there's no proof of stability whatsoever for it. Better try it with
> > > uncritical data partitions (portage tree, distfiles) first.
> >
> > Yet if you do, the latest GRUB boots from ext4 partitions, so you
> > don't need to separate /boot.
> >
> >
>
> I heard it can boot from ext4 using a patch that is not 100% safe...
> Does anyone have positive (or negative) experience with that?

You don't need to apply any patch; it comes with GRUB. I didn't get any
"WARNING: this patch will fuck your box" messages when I installed it.
In my experience I haven't seen any difference between it and the 25 or
so other patches that Gentoo applies to GRUB.

Resizing physical volume for lvm.
 

On Sunday 22 March 2009 22:42:39 Momesso Andrea wrote:
> Thanks for the advice. Will be a problem for lvm if I add a partition
> before it? I mean, will I need to change any config files while lvm is
> gonna reside on sda4 instead of sda3?

It's not a problem. LVM scans the drive looking for pvs and uses them as it
finds them. You can see this behaviour when running 'vgchange -a y'. It
doesn't need or really use the partition number at all.

You may have such things in lvm config files somewhere. If it becomes
problematic, simply remove/comment those entries.

--
alan dot mckinnon at gmail dot com

Resizing physical volume for lvm.
 

On Sunday 22 March 2009 23:00:07 Momesso Andrea wrote:
> On Sun, 22 Mar 2009 22:35:35 +0200
>
> Alan McKinnon <alan.mckinnon@gmail.com> wrote:
> > On Sunday 22 March 2009 22:15:14 Momesso Andrea wrote:

> > Your data is safe if you do exactly the steps you said above.
>
> pvresize /dev/sda3
> /dev/sda3: too many metadata areas for pvresize
>
> Looks like I cannot expand it...

This code commit is giving the error:

http://sources.redhat.com/ml/lvm2-cvs/2008-09/msg00001.html

and a solution can be found in this thread (courtesy of that nice man Mr.
Google):

http://archives.free.net.ph/message/20081129.151331.dd8edce0.en.html
>
> ---
> TopperH
> http://topperh.blogspot.com

--
alan dot mckinnon at gmail dot com