LVM and LVM2 support in Grub

LVM and LVM2 support in Grub

[Dag Wieers]

Hi guys,

Today I met Alasdair Kergon again and Tim brought up the question when we 
can expect LVM support in Grub. This is a feature that is now missing for 
some time and a lot of people are waiting for this.

Alasdair is very interested to make it possible to have Grub use some of 
the LVM functionality to allow for this directly which would probably work 
much better than the existing SoC project that apparently does not support 
the full set of LVM installations that exist.

Would it be posible to have this discussed or have a patch accepted for 
this ? Alasdair said that here at LinuxTag the past few days 7 of Red 
Hat's LVM engineers were present and they had some internal meetings. I 
am pretty sure Red Hat can make some resources available to make this 
work.

What is necessary to get this thing going and committed upstream ? Who can 
help with this from the Grub community ?

PS I am just trying to ignite some discussion so that I can use this 
myself as a happy Linux, Grub and LVM user ;-)

Thanks in advance,
-- 
--   dag wieers,  dag@wieers.com,  http://dag.wieers.com/   --
[Any errors in spelling, tact or fact are transmission errors]

Re: LVM and LVM2 support in Grub

[Robert Millan]

On Fri, May 30, 2008 at 12:52:24PM +0200, Dag Wieers wrote:
> Hi guys,
> 
> Today I met Alasdair Kergon again and Tim brought up the question when we 
> can expect LVM support in Grub. This is a feature that is now missing for 
> some time and a lot of people are waiting for this.

LVM is already supported, although it's a bit buggy and some rare use cases
don't work well yet.

If you find bugs, reports are welcome.  As for unsupported use case, it doesn't
work if you're booting from the LVM device itself.  We already know why this
happens, but nobody had time to fix it (help is welcome, I can give more
details if desired).

Thanks

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)

Re: LVM and LVM2 support in Grub

[Dag Wieers]

On Fri, 30 May 2008, Robert Millan wrote:

> On Fri, May 30, 2008 at 12:52:24PM +0200, Dag Wieers wrote:
>> Hi guys,
>>
>> Today I met Alasdair Kergon again and Tim brought up the question when we
>> can expect LVM support in Grub. This is a feature that is now missing for
>> some time and a lot of people are waiting for this.
>
> LVM is already supported, although it's a bit buggy and some rare use cases
> don't work well yet.
>
> If you find bugs, reports are welcome.  As for unsupported use case, it doesn't
> work if you're booting from the LVM device itself.  We already know why this
> happens, but nobody had time to fix it (help is welcome, I can give more
> details if desired).

I asked the question because Alasdair mentioned that the current 
implementation doesn't use the existing LVM framework and he would prefer 
that, instead of having the functionality as a whole included in Grub, it 
relies on the LVM infrastructure that is maintained by the LVM developers.
And as a result would be a much more complete (and 
maintained) implementation than is currently offered.

To me it looks like it could just compile and link against the LVM API. 
That would certainly provide for a much better implementation than the 
current as it would be maintained by the LVM developers directly.

Now, I much more prefer Alasdair to join the discussion as I am just an 
incapable user :-) but since we are at LinuxTag it may take some time.

I promised I would ignite the discussion, so my job is over ;-)
-- 
--   dag wieers,  dag@wieers.com,  http://dag.wieers.com/   --
[Any errors in spelling, tact or fact are transmission errors]

Re: LVM and LVM2 support in Grub

[Robert Millan]

On Fri, May 30, 2008 at 01:23:16PM +0200, Dag Wieers wrote:
> 
> I asked the question because Alasdair mentioned that the current 
> implementation doesn't use the existing LVM framework and he would prefer 
> that, instead of having the functionality as a whole included in Grub, it 
> relies on the LVM infrastructure that is maintained by the LVM developers.
> And as a result would be a much more complete (and 
> maintained) implementation than is currently offered.
> 
> To me it looks like it could just compile and link against the LVM API. 
> That would certainly provide for a much better implementation than the 
> current as it would be maintained by the LVM developers directly.

I agree that it potentially can be a great benefit;  but it could also be a
problem.  Please could you let us know about:

  - Does the LVM framework provide a practical means of linking it
    into GRUB (not just the user part, also the freestanding code)?

  - Is its license compatible with the GPL (version 3)?

  - Will it increase the size of our lvm.mod?  Size is critical here, because
    it's highly desireable that lvm.mod fits in core.img which fits in
    the post-mbr region.

Thanks

-- 
Robert Millan

<GPLv2> I know my rights; I want my phone call!
<DRM> What good is a phone call… if you are unable to speak?
(as seen on /.)