Re: [linux-lvm] 2.03 Volume readable by 2.02?

["John L. Poole" <jlpoole56@gmail.com>]

Thank you, John Stoffel, for your kind offer to help.  I am faced
with several alternatives at this juncture and feel that enlisting
general help would be counter-productive.  I don't want you to
spend your time on an approach only to have me change the whole paradigm,
i.e. installing Gentoo as Dom0 (and wrestling wieh EUFI) so there is
no disparity between lvm versions.  I've invested several hours
building out my guest Gentoo, so I hate to risk having to do it
over again, or trying to archive and copy it to an attached drive and then
back into a partition using fdisk or parted.

I asked the question below hoping a developer familiar with the 
specifications
of the mapping schema for lvm might answer.  Are you one of the
developers at Redhat?

Since I posted, I changed my client's lvm to 2.0.3.  This upgrade
and near match to the host ("Dom0") version ought to negate any
disparity issues between versions -- I would hope.

Even with my Gentoo client having 2.0.3 trying to discover the
lvm shares created by the Debian host is failing at the start
of the kernel.  I think my problem is the initramfs is not
properly mapping to the lvm system.  This may be a Xen issue or
something missing in my guest kernel and/or initramfs.

The question I posed:

    should tools of lvm v. 2.02.187 be able to read and access
    a volume created by 2.03.02?

raises the question of whether a previous version at 2.02 can
read a mapped system created by a version at 2.03.  An answer
could be helpful for others working with Virtual Machines so I
hope someone who might know the answers responds.

Kind regards,

John Poole


I could not find a description of posting etiquette for this forum.

On 1/31/2021 3:47 PM, John Stoffel wrote:
>>>>>> "John" == John L Poole <jlpoole56@gmail.com> writes:
> John> I am having problems with a kernel and/or initial ram file
> John> system booting up in a Xen environment.
>
> Do you have any logs of the error(s) when booting up?
>
> Can you show us the configuration of your Xen guest and it's LVM
> volumes, VG and PVs as well?  The more details the better.
>
> I personally don't do Gentoo or Xen, so I can't help there.  But I can
> ask you to post more details.  A boot log would be very helpful.
>
>
> John> The guest virtual machine's root file system is on an lvm volume created
> John> in Debian.  Dom0 is Debian.
> John> lvm on Debian is: 2.03.02(2).
>
> John> The guest virtual machine is in Gentoo and I have lvm  2.02.187-r2
> John> installed therein.  I built my
> John> kernel and initramfs against the 2.02 version of lvm.
>
> John> My question: should tools of lvm v. 2.02.187 be able to read and access
> John> a volume created by 2.03.02?
>
> John> Does the version change between 2.02 and 2.03 mean that the file system
> John> created by 2.03 tools
> John> may not be readable or accessible by 2.02 tools and libraries?  I'm
> John> doubting it, but asking.
>
> John> Gentoo's highest version of lvm is 2.02.187-r2; Gentoo developers have
> John> lvm 2.03 masked with the note:
>
> John>       [2.03] Needs LOTS of testing, broke boot on my laptop
> John>       in early attempts, maybe needs matching genkernel work?
>
> John> source: https://packages.gentoo.org/packages/sys-fs/lvm2
>
> John> Thank you,
>
> John> John Poole
>
> John> _______________________________________________
> John> linux-lvm mailing list
> John> linux-lvm@redhat.com
> John> https://www.redhat.com/mailman/listinfo/linux-lvm
> John> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
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