Mailinglist Archive: opensuse-storage (11 mails)

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Re: [opensuse-storage] Review partitioning requirements - x86
On Fri, Jul 08, 2016 at 02:19:10PM +0200, Ancor Gonzalez Sosa wrote:
On 07/08/2016 12:26 PM, Thorsten Kukuk wrote:
On Fri, Jul 08, Ancor Gonzalez Sosa wrote:

On 05/20/2016 08:46 AM, Jiri Srain wrote:

I am not sure why the /boot parititon is needed here. If you have
sufficently
large MBR gap to embed stage2 image, then it could boot off from LVM
volumes
directly.

We did that based in the Michael Chang's comment that is documented at
https://github.com/yast/yast-storage-ng/blob/master/doc/boot-partition.md#general

Our conclusion from that comment was "ditching /boot is harder than
expected, so to stay safe always propose /boot with LVM".
That's reflected in the summary section here
https://github.com/yast/yast-storage-ng/blob/master/doc/boot-partition.md#general-1

Ok, I understand the problems with grub-once, but: always creating
a /boot with LVM makes snapshots/rollback with LVM impossible :(

Looks like this needs a further discussion with the bootloader people,
if there isn't a solution for at least GPT based partition schemes or so.


"with raid, eLVM and LVM
- on GPT always create a GRUB partition
- otherwise, always create a /boot partition"

Isn't it?

Ok, and this is what we have today, fine with me.

Is the GRUB partition required in all architectures when LVM is used?

Not really. It depends on the firmware type. In short the bios_grub is reserved
space for bootloader's stage2 image that can't fit into disk's 512 byte master
boot record.

For legacy pc bios + gpt table, bios_grub partition is required for booting lvm
paritition directly. If you don't create bios_grub partition, then you'll have
to create (rather suboptimal) separate partition for /boot without any
underlying volume managers like lvm or mdadm. In other words, bios_grub is
required for gpt on legacy pc bios if you don't want to require a separate boot
partition, which is out to system's root file system so may not be able to
fulfill desired storage management plans, for eg implementing btrfs or even lvm
snapshots on the full system with kernel and so on.

For PPC64, I don't think bios_grub is required as long as firmware will boot
PReP partition directly and never use MBR.


Right now, for PPC64+LVM we always require /boot (similar to what we
had in x86), as you can see in
https://github.com/yast/yast-storage-ng/blob/master/doc/boot-requirements.md

Should this current block [1] be something like this[2]?

[1]
with a LVM-based proposal
if there are no PReP partitions
requires /boot and PReP partitions
if the existent PReP partition is not in the target disk
requires /boot and PReP partitions
if there is already a PReP partition in the disk
only requires a /boot partition

[2]
with a LVM-based proposal
with a MS-DOS partition table
if there are no PReP partitions
requires /boot and PReP partitions
if the existent PReP partition is not in the target disk
requires /boot and PReP partitions
if there is already a PReP partition in the disk
only requires a /boot partition
with a GPT partition table
if there are no PReP partitions
requires GRUB and PReP partitions
if the existent PReP partition is not in the target disk
requires GRUB and PReP partitions
if there is already a PReP partition in the disk
only requires a GRUB partition

So that [2] looks wrong to me ...

Thanks,
Michael


Cheers
--
Ancor González Sosa
YaST Team at SUSE Linux GmbH
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