Different uses of the term boot partition

[billcarson]

I am a little confused as to terminology:

When installing SUSE on RAID partitions YAST gets upset if you don't create a separate boot partition for the boot directory (/boot ), which contains /boot directory files – e.g. STAGE 2 files, kernel images, etc. This is referred to as the “boot partition”

But the “boot partition” is also used to refer to where the boot CODE is stored, e.g.using Setup to install GRUB on (hd0) so that the MBR will points to the Stage 2 Grub files. In this case , wouldn't your first primary partition be your “boot partition”
And if you wanted to put the boot code on your root partition, then I would imagine that your root partition could also be called your “boot” partition.

Any help with this would be much appreciated.


bill

[gogalthorp]

This might help

Quick HOWTO : Ch07 : The Linux Boot Process - Linux Home Networking

[billcarson]

Thanks so much for responding.

I've read these references before.

It is, however, exactly these type of references that occasionally
refer to the "boot partition" in different variations.

Again, my question is as before:
When installing SUSE on RAID partitions YAST gets upset if you don't create a separate boot partition for the boot directory (/boot ), which contains /boot directory files – e.g. STAGE 2 files, kernel images, etc. This is referred to as the “boot partition”

But the “boot partition” is also used to refer to where the boot CODE is stored, e.g.using Setup to install GRUB on (hd0) so that the MBR will points to the Stage 2 Grub files. In this case , wouldn't your first primary partition be your “boot partition”
And if you wanted to put the boot code on your root partition, then I would imagine that your root partition could also be called your “boot” partition.

thanks again for you interest
billcarson

[gogalthorp]

You have to understand the directory structure. A Hard disk partition can be mounted as a directory. My guess is the with RAID you would not want to treat your boot stuff as RAIDed since it must be able to be read before the kernel loads and the RAID functions kick in. Thus you need to mount your boot directory as a separate partition. So you need a small separate partition to hold this so that the kernel etc can be loaded. So this is both a partition and a directory. It is a directory that points to the "boot" partition ie it is the samething just looked at from different angles

Normally the boot directory resides in the / (root) partition.

[devils casper]

LVM partitions do not support boot flag and its necessary to create separate /boot partition whenever one uses LVM.

RAID has nothing to do with separate /boot partition.

[gogalthorp]

Thats good to know

[apoorv_khurasia]

But the “boot partition” is also used to refer to where the boot CODE is stored, e.g.using Setup to install GRUB on (hd0) so that the MBR will points to the Stage 2 Grub files. In this case , wouldn't your first primary partition be your “boot partition”
And if you wanted to put the boot code on your root partition, then I would imagine that your root partition could also be called your “boot” partition.

The part of the disk that stores Stage 1 information is never called boot partition...if someone calls it that correct him....the correct term is boot sector. As a standard its size is exactly 512 bytes. You cannot hold any other data in it and it is not formatted (its raw)...the /boot directory can exist anywhere (even on a FAT32 partition in case of GRUB or any other bootloader that can read FAT) and most people (esp. server people) mount it on a separate partition than the root partition. It is then when you (can) call it a partition.

[billcarson]

The part of the disk that stores Stage 1 information is never called boot partition...if someone calls it that correct him....the correct term is boot sector. As a standard its size is exactly 512 bytes. You cannot hold any other data in it and it is not formatted (its raw)...the /boot directory can exist anywhere (even on a FAT32 partition in case of GRUB or any other bootloader that can read FAT) and most people (esp. server people) mount it on a separate partition than the root partition. It is then when you (can) call it a partition.

So then let’s look at this example. .
I have a triple boot with SUSE loading the bootloader :

/dev/sda 160Gb --dev/sda1 20G NTFS 7 WinXP
-dev/sda2 21G Linux (ext3) 83 Ubuntu
-dev/sda3 502MB Swap Swap
-dev/sda4 120Gb Ext’d
-dev/sda5 Linux(ext 3) 83 /boot SUSE
-dev/sda6 Linux (ext 3) 83 “/” SUSE

So you are saying sdb5 is the “boot partition”, because it contains the /boot directory files. Correct?
And since GRUB was loaded on (hd0), Stage 1 went to the MBR, Stage 2 went to the /boot directory – and we still can call sdb5 the boot partition.

Then what would have happened if I had installed the bootloader to the root partition? (apparently people do this)
Where would Stage1 and Stage 2 have gone?
My guess is Stage 1 to the root partition, and Stage 2 to the /boot directory partition
And the boot partition in this example would be?

Thanks for all the input

bc

[apoorv_khurasia]

Then what would have happened if I had installed the bootloader to the root partition? (apparently people do this)
Where would Stage1 and Stage 2 have gone?
My guess is Stage 1 to the root partition, and Stage 2 to the /boot directory partition
And the boot partition in this example would be?

Thanks for all the input

bc

You are right (and welcome)....the boot partition is still where your stage 2 is....the stage 1 is on the root partition and the first 512 bytes of the root partition make the boot sector now. You can have any number of boot sectors on your disk(s) but only one master boot sector (MBR). To use the other boot sectors you should be able to somehow be able to redirect your CPU from MBR to the first address of these sectors....then the operation will continue normally.

[billcarson]

This has all been very helpful.
Apoorv and others finally set this terminology straight.

I guess in retrospect I could have left my MBR completely alone and not followed through and made GRUB go to (hd0). Its funny how so many Linux installs want you by default to load the GRUB bootloader (stage1) on (hd0).

Now that I successfully created this triple boot ( and understood it a little bit better!) I guess I should create some type of backup GRUB Rescue USB Key.

Should the GRUB install commands, 'root' and 'setup', place both Stage 1 and Stage2 files onto the USB key. OR just Stage1?

BC