Grub2 mapping drives

[trilarian]

First, thanks for responding. Don't take any of my griping as personal, it is all directed at grub2 and I appreciate your time in explaining it to me.

Grub2 has Grub rescue which in my opinion is rather useless. The true Grub2 prompt however is very similar to the Grub1 prompt and it is the one that you press the "c" key before booting up a system.

Something else must be wrong then when it is installed as an upgrade. It's been awhile, but I remember not being able to boot my own computer either when trying to play with grub2. The only time I ever got grub2 to successfully boot anything is when they included it in the Debian net-install as an option. However, after the first apt-get upgrade (which updated the kernel) it became unbootable again. On the flip side, I haven't ever come across something grub can't boot.

In this recent case, grub_rescue> pops up immediately after the RAM test, so there is no time to input any key sequence and there is no information sent to the screen. Furthermore, grub rescue doesn't even have enough commands available to actually boot the system (both linux and kernel are 'not found' when invoked) - so shouldn't even be available as it currently is imho.

The "help" command is there same as Grub1. Grub2 does have "ls" in place of "geometry" and it works like Linux kernel's "ls". The new ls command can list any directory including those from a NTFS partition. Thus Grub2 can be installed inside a MS Windows. The tab to auto complete is there too so use Grub2 prompt and disregard Grub rescue which is triggered if the second stage is broken.

If they have the code for ls and help, why isn't it in rescue? Why is rescue the default error catcher instead of grub2 shell? Honestly I could care less about installing grub unto a NTFS partition... what scenario would this be good for outside of just saying I did it? If it is windows only, let the regular windows boot loader take care of things - it is faster and easily fixable. If it is a dual boot, install grub to the linux partition or in the MBR. If it's pure Linux, why have NTFS anyway? Am I missing something neat?

There are only small changes between the two Grub which I got in my Ubuntu. The Grub1 booting instructions from menu.lst is listed here

title	Ubuntu 9.04, kernel 2.6.28-11-generic
uuid	e64d0e8b-63f1-4e79-917d-06a809eba07e
kernel /boot/vmlinuz-2.6.28-11-generic root=UUID=e64d0e8b-63f1-4e79-917d-06a809eba07e ro quiet splash 
initrd	/boot/initrd.img-2.6.28-11-generic

and the Grub2 translation in grub.cfg, after using Ubuntu package manager installing Grub2 gave

menuentry "Ubuntu, linux 2.6.28-11-generic" {
set root=(hd0,6)
search --fs-uuid --set e64d0e8b-63f1-4e79-917d-06a809eba07e
linux  /boot/vmlinuz-2.6.28-11-generic root=UUID=e64d0e8b-63f1-4e79-917d-06a809eba07e ro  quiet splash
initrd /boot/initrd.img-2.6.28-11-generic
}

I highlighted the difference in red.

So if I'm reading this right... if the below works for grub if I manually type it in, why can't what is below that work for grub2? And how do you manually boot a system with grub2 when there isn't a linux or kernel command available?

Grub Example:

root (hd0,0)
kernel /boot/vmlinuz-2.6.32-trunk-amd64 root=/dev/hda1 ro
initrd /boot/initrd-2.6.32-trunk-amd64
boot

Grub2 (doesn't work, but should):

set root (hd1,1)
linux /boot/vmlinuz-2.6.32-trunk-amd64 root=/dev/hda1 ro
initrd /boot/initrd-2.6.32-trunk-amd64
boot

Thus the differences are very small. Also I don't normally bother with uuid reference and have booted the system "manually" in Grub1 with commands

root (hd0,5)
kernel /boot/vmlinuz-2.6.28-11-generic root=/dev/sda6 ro  
initrd	/boot/initrd.img-2.6.28-11-generic
boot

and if I use Grub2 it is just

set root=(hd0,6)
linux /boot/vmlinuz-2.6.28-11-generic root=/dev/sda6 ro  
initrd	/boot/initrd.img-2.6.28-11-generic
boot

The green bits are by tab auto complete.

This just baffles me. Unless grub2_rescue is a retarded subset of code not meant to ever, ever, ever be used, this simply is not true on my system. Hitting tab never fills in the remainder of a command or file name, and does not give partial matches. Furthermore, typing in "linux /boot/..." line kept returning "command linux not found". I'm sure I didn't misspell it.... I tried typing it a few times, tried casing, tried l tab, etc. but nothing.

The three useful features in Grub2 (not found in Grub1) are

(1) Grub2 can read ntfs partition and so it can be installed as a stand alone system inside a MS Windows. I have tried this with Xp and Win7.

I guess I still don't see the significance of this... maybe you can enlighten me to a use I'm overlooking?

(2) Grub2 is factory-ready for gpt partitions so it can work seamlessly with hard disks in excess of 2TB size.

This may eventually be an issue, but the more I think about, probably never. Right now I have 2x 1TB drives in software RAID-0 - effectively 2TBs - on my server. I'm assuming since the way you load up the raid modules (and encryption modules) is by making the small /boot partition a raid mirror unencrypted (so in grub's chain of events, a single partition on a single drive) it will never see that upper limit. I can't think of any reason in my life time to need a /boot over 2TB.

For the rare case of having another OS installed in a partition over 2TB I guess this is useful, but it is an awful waste of space. Put the OS on a smaller partition, and fill the rest as a shared storage partition readable by all installed OS.

(3) Grub1 will complain if the partition to be booted is beyond the 1.3TB position in a hard disk with a error complaining "the number of cylinders exceed the maximum supported by the Bios". Grub2 has overcome this limitation.

I haven't seen this error. My setup was listed above, but outside of /boot (which is 150MB x2) the rest is one large partition on top of the software raid which is one encrypted partition, that once unlocked is subdivided with LVM. Since I haven't received the error you mention, I can only assume the 1.3TB limit is again only assigned to /boot or the root partition of say a Windows install. That again brings up my rebuttal to #2, put the OS in less than 2TB (or 1.3TB in this case) and make the largest partition be your storage partition that is readable by all.

I don't see any advantage to throwing everything in one partition, and if it is the only partition on the drive - like in the case of a windows only install (even though as of Vista? windows makes a smaller boot partition) - then use the windows boot loader.

Here is a simple solution for grub2 to be instantly usable... Grub2 should have a working shell that will let you manually boot if the auto script errors out. Delete all code relating to grub_rescue as fast as humanely possible. Add an alias to any commands that simply have a new name (like linux vs kernel, map vs drivemap, etc.) so that users of grub feel at home and the current grub2 syntax still works. I don't see a need for new command names when the function is the same - grub2 uses a different config file if they were worried about that.