[arch-general] A question specifically about upgrading an existing arch system from grub legacy to grub without UEFI or GPT
I have been following the discussions in various places including on this list about the forthcoming change from grub to become grub-legacy and the default bootloader becoming grub2. On all my arch systems I have grub with MBR partitioning, booting to BIOS initially - and none of my systems is modern enough to have UEFI instead of BIOS. So I have been reading up on what I will need to do when grub2 version 2.00 appears in [core] - and how to successfully achieve the changeover. However I still cannot determine if it will be "necessary" to make sure that there is a post-MBR gap of 2MiB between the MBR and the first partition when the system will remain using MBR partitioning and grub2 will be the bootloader. So this applies to systems with no GPT partitions, and no UEFI. In my systems that have been running some time some have 64 sectors to where the start of the first partition is, and others have 2,000 sectors which is about 1MiB - and I still don't know if grub2 version 2.00 will not work on those systems or not. I do know that other distros such as Fedora version F16 have systems running successfully using grub2 prior to version 2.00 with MBR partitioning and BIOS and boot perfectly well without the 2MiB post MBR gap. Perhaps this changes with the release of grub2 version 2.00? Achieving a post-MBR gap of at least 2MiB will be a painful process as shrinking the first partition and then moving it towards partition 2 with an MBR partitioned disk is time consuming and not always successful in those systems where in the past I have adjusted the partitions on a drive. Maybe the recent versions of tools such as PartedMagic will cope better than it did a couple of years ago? Can someone help out with a clear explanation please. I am usually pretty good with upgrades and preparation but this has foxed me! i.e. specifically for a BIOS-MBR hard drive using grub2 that it is vital to have a post-MBR gap of at least 2 MiB (where no GPT partitioning will be in use)? Thanks -- mike c
On Mon, Jul 02, 2012 at 05:26:23PM +0100, mike cloaked wrote:
I have been following the discussions in various places including on this list about the forthcoming change from grub to become grub-legacy and the default bootloader becoming grub2.
On all my arch systems I have grub with MBR partitioning, booting to BIOS initially - and none of my systems is modern enough to have UEFI instead of BIOS.
So I have been reading up on what I will need to do when grub2 version 2.00 appears in [core] - and how to successfully achieve the changeover. However I still cannot determine if it will be "necessary" to make sure that there is a post-MBR gap of 2MiB between the MBR and the first partition when the system will remain using MBR partitioning and grub2 will be the bootloader. So this applies to systems with no GPT partitions, and no UEFI.
In my systems that have been running some time some have 64 sectors to where the start of the first partition is, and others have 2,000 sectors which is about 1MiB - and I still don't know if grub2 version 2.00 will not work on those systems or not. I do know that other distros such as Fedora version F16 have systems running successfully using grub2 prior to version 2.00 with MBR partitioning and BIOS and boot perfectly well without the 2MiB post MBR gap. Perhaps this changes with the release of grub2 version 2.00?
Achieving a post-MBR gap of at least 2MiB will be a painful process as shrinking the first partition and then moving it towards partition 2 with an MBR partitioned disk is time consuming and not always successful in those systems where in the past I have adjusted the partitions on a drive. Maybe the recent versions of tools such as PartedMagic will cope better than it did a couple of years ago?
Can someone help out with a clear explanation please. I am usually pretty good with upgrades and preparation but this has foxed me! i.e. specifically for a BIOS-MBR hard drive using grub2 that it is vital to have a post-MBR gap of at least 2 MiB (where no GPT partitioning will be in use)?
Why do you need to upgrade to grub2? Even if grub-legacy won't be in the official repositories, it'll be in the AUR. Also, you don't need to reinstall grub every now and then, so i don't see the need to upgrade.
On Mon, Jul 2, 2012 at 5:39 PM, gt <static.vortex@gmx.com> wrote:
Why do you need to upgrade to grub2? Even if grub-legacy won't be in the official repositories, it'll be in the AUR. Also, you don't need to reinstall grub every now and then, so i don't see the need to upgrade.
OK if the general policy will be that for existing systems there is no need to upgrade grub in this situation that will be great - and if grub-legacy is in the AUR but no further development or changes takes place then that would satisfy me and there would be presumably no need to install the grub-legacy package from AUR? Just continue to update using pacman -Syu? A further question then arises - let's say there is a system on which arch is not yet running and a new arch install needs to be done - but that the disk is pre-partitioned and has perhaps Windows XP or Windows 7 that the user would like to preserve with a dual boot system - and which perhaps has an OEM (HP) recovery partition between the MBR and the NTFS Windows partition with a post-MBR gap of 64 sectors. When installing arch when the default is grub2 - would it then need a larger post-MBR gap to achieve a successful (and bootable) install? (This is for the presumption that it has BIOS and MBR partitioning only - and again no GPT or UEFI) - or would an install along the lines that most people have been used to doing with existing install media work perfectly well? -- mike c
On Jul 2, 2012 5:48 PM, "mike cloaked" <mike.cloaked@gmail.com> wrote:
On Mon, Jul 2, 2012 at 5:39 PM, gt <static.vortex@gmx.com> wrote:
Why do you need to upgrade to grub2? Even if grub-legacy won't be in the official repositories, it'll be in the AUR. Also, you don't need to reinstall grub every now and then, so i don't see the need to upgrade.
OK if the general policy will be that for existing systems there is no need to upgrade grub in this situation that will be great - and if grub-legacy is in the AUR but no further development or changes takes place then that would satisfy me and there would be presumably no need to install the grub-legacy package from AUR? Just continue to update using pacman -Syu?
That's what I assume also. I'm using syslinux so I am not directly affected by the upgrade, but always good to know. Also since this could potentially break you system the update would be in the news add well when it happens, along with info on how to proceed on various situations.
A further question then arises - let's say there is a system on which arch is not yet running and a new arch install needs to be done - but that the disk is pre-partitioned and has perhaps Windows XP or Windows 7 that the user would like to preserve with a dual boot system - and which perhaps has an OEM (HP) recovery partition between the MBR and the NTFS Windows partition with a post-MBR gap of 64 sectors. When installing arch when the default is grub2 - would it then need a larger post-MBR gap to achieve a successful (and bootable) install? (This is for the presumption that it has BIOS and MBR partitioning only - and again no GPT or UEFI) - or would an install along the lines that most people have been used to doing with existing install media work perfectly well?
-- mike c
On Mon, Jul 2, 2012 at 5:26 PM, mike cloaked <mike.cloaked@gmail.com> wrote:
I have been following the discussions in various places including on this list about the forthcoming change from grub to become grub-legacy and the default bootloader becoming grub2.
On all my arch systems I have grub with MBR partitioning, booting to BIOS initially - and none of my systems is modern enough to have UEFI instead of BIOS.
So I have been reading up on what I will need to do when grub2 version 2.00 appears in [core] - and how to successfully achieve the changeover. However I still cannot determine if it will be "necessary" to make sure that there is a post-MBR gap of 2MiB between the MBR and the first partition when the system will remain using MBR partitioning and grub2 will be the bootloader. So this applies to systems with no GPT partitions, and no UEFI.
In my systems that have been running some time some have 64 sectors to where the start of the first partition is, and others have 2,000 sectors which is about 1MiB - and I still don't know if grub2 version 2.00 will not work on those systems or not. I do know that other distros such as Fedora version F16 have systems running successfully using grub2 prior to version 2.00 with MBR partitioning and BIOS and boot perfectly well without the 2MiB post MBR gap. Perhaps this changes with the release of grub2 version 2.00?
Achieving a post-MBR gap of at least 2MiB will be a painful process as shrinking the first partition and then moving it towards partition 2 with an MBR partitioned disk is time consuming and not always successful in those systems where in the past I have adjusted the partitions on a drive. Maybe the recent versions of tools such as PartedMagic will cope better than it did a couple of years ago?
Can someone help out with a clear explanation please. I am usually pretty good with upgrades and preparation but this has foxed me! i.e. specifically for a BIOS-MBR hard drive using grub2 that it is vital to have a post-MBR gap of at least 2 MiB (where no GPT partitioning will be in use)?
Thanks
The best I could guess at for the way an upgrade with my systems would work - is that if I have a disk with a 64 sector post-MBR gap (where 1 sector is 512 bytes), is that grub2 with BIOS-MBR and a /boot partition, would still work but that it might be more efficient putting it on a disc where the post-MBR gap is 2MiB - but changing to the larger post-MBR gap is not an "essential" change prior to changing from grub to grub2 - though I would like someone more expert than me to tell me if I am right or wrong! Thanks -- mike c
participants (3)
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gt
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Leonidas Spyropoulos
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mike cloaked