[SOLVED] Grub Confusion

Madbunny · 2011-01-21 09:59:31

Hi All,

I currently have two partitions sda3 & sda5 which I can boot into. I am able to choose either one to boot from the frub menu on bootup. Initially when I installed Arch, I made a separate partition for /boot on sda1, but I'm not convinced that I have set it up right.

For instance, both sda3 and sda5 have a /boot folder under root. However, only changes to the menu.lst file on sda3 have any effect. So am I correct in assuming I have actually installed grub on sda3 as opposed to sda1?

How can I have a separate /boot which gets mounted on both sda3 and sda5 so that I don't have to mount sda3 in order to make changes to my menu.lst file

Cheers

Last edited by Madbunny (2011-01-23 07:28:15)

Mr Green · 2011-01-21 11:13:51

Really depends on your partition table [fstab] you do not say if you dual boot

Grub is usually installed to MBR of first drive [that is seen on booting system]

Madbunny · 2011-01-21 12:29:44

I'm not dual booting, only have arch linux installed on both sda3 and sda5.

My fstab has no reference to /boot.

Varg · 2011-01-21 12:36:41

You have two Arch installs ? I don't know if it's good to have two machines with the same /boot partition. I would give each machine it's own /boot partition...
Which one was installed first ?
I think that the machine on sda3 owns the boot partition on sda1 and that the machine on sda5 has the /boot folder on it's root partition.

And please post your fstab and menu.lst files.

Last edited by Varg (2011-01-21 12:37:51)

Madbunny · 2011-01-21 12:55:47

Varg wrote:

You have two Arch installs ? I don't know if it's good to have two machines with the same /boot partition. I would give each machine it's own /boot partition...
Which one was installed first ?
I think that the machine on sda3 owns the boot partition on sda1 and that the machine on sda5 has the /boot folder on it's root partition.
And please post your fstab and menu.lst files.

fstab on sda3

 
# 
# /etc/fstab: static file system information
#
# <file system>        <dir>         <type>    <options>          <dump> <pass>
devpts                 /dev/pts      devpts    defaults            0      0
shm                    /dev/shm      tmpfs     nodev,nosuid        0      0

#/dev/cdrom             /media/cd   auto    ro,user,noauto,unhide   0      0
#/dev/dvd               /media/dvd  auto    ro,user,noauto,unhide   0      0
#/dev/fd0               /media/fl   auto    user,noauto             0      0

/dev/sda2 swap swap defaults 0 0
/dev/sda3 / ext4 defaults 0 1
#/dev/sda5 / ext4 defaults 0 1

/dev/datavg/lv_home     /home ext3 acl,user_xattr 1 2
/dev/datavg/lv_audio     /home/brian/Documents/audio ext3 acl,user_xattr 1 2
/dev/datavg/lv_video    /home/brian/Documents/video xfs defaults
/dev/datavg/lv_photos   /home/brian/Documents/photos ext3 acl,user_xattr 1 2
/dev/datavg/lv_downloads  /home/brian/Documents/downloads ext3 acl,user_xattr 1 2
/dev/datavg/lv_images   /home/brian/Documents/images xfs defaults

Menu.lst on sda3

# Config file for GRUB - The GNU GRand Unified Bootloader
# /boot/grub/menu.lst

# DEVICE NAME CONVERSIONS 
#
#  Linux           Grub
# -------------------------
#  /dev/fd0        (fd0)
#  /dev/sda        (hd0)
#  /dev/sdb2       (hd1,1)
#  /dev/sda3       (hd0,2)
#

#  FRAMEBUFFER RESOLUTION SETTINGS
#     +-------------------------------------------------+
#          | 640x480    800x600    1024x768   1280x1024
#      ----+--------------------------------------------
#      256 | 0x301=769  0x303=771  0x305=773   0x307=775
#      32K | 0x310=784  0x313=787  0x316=790   0x319=793
#      64K | 0x311=785  0x314=788  0x317=791   0x31A=794
#      16M | 0x312=786  0x315=789  0x318=792   0x31B=795
#     +-------------------------------------------------+
#  for more details and different resolutions see
#  [url]http://wiki.archlinux.org/index.php/GRUB#Framebuffer_Resolution[/url] 

# general configuration:
timeout   2
default   0
color light-blue/black light-cyan/blue

# boot sections follow
# each is implicitly numbered from 0 in the order of appearance below
#
# TIP: If you want a 1024x768 framebuffer, add "vga=773" to your kernel line.
#
#-*

# (0) Arch Linux
title  Arch Linux
root   (hd0,2)
kernel /boot/vmlinuz26 root=/dev/sda3 ro vga=773
initrd /boot/kernel26.img

# (1) Arch Linux 2
title  Arch Linux (sda5)
root   (hd0,4)
kernel /boot/vmlinuz26 root=/dev/sda5 ro vga=773
initrd /boot/kernel26.img


# (3) Arch Linux (SDA5)
#title Arch Linux Copy 2
#root  (hd0,4)
#kernel /boot/vmlinuz26 root =/dev/sda5 ro vga=773
#initrd /boot/kernel26.img

(2) ArchLinux Copy Fallback
title Arch Linux Fallback
root   (hd0,2)
kernel /boot/vmlinuz26 root=/dev/sda3 ro vga=773
initrd /boot/kernel26-fallback.img



# (2) Windows
#title Windows
#rootnoverify (hd0,0)
#makeactive
#chainloader +1

sda5 is simply a copy of sda3. It used as a backup for when I do upgrades. As I said, editing the menu.lst on sda5 has no effect whereas changes on sda3 have an effect.

Varg · 2011-01-21 13:11:42

I think that the boot partition of the sda3 machine is actually just a folder in /
I found something cool after a quick search on google, try this:

$ df /boot

This will show you the partition of the boot folder.

When it's indeed on sda3, as I suspect, you might try to mount sda1 manually and see what's on that partition.

Then I was thinking to add sda1 to fstab and just copy /boot to sda1, remove the folder on sda3 and edit the menu.lst file but I have absolutely no idea if that is a safe thing to do. So you better wait for someone else to give you an answer.
On the other hand, when you would just do a reinstall of Arch to fix this, please try what I suggested and tell me if it works

Last edited by Varg (2011-01-21 13:29:24)

Madbunny · 2011-01-21 22:07:48

I have tried mounting sda1 but I haven't been able to. It keeps telling me I have the wrong filesystem, even though I've tried all of them. If I had /boot on a separate partition, wouldn't it have to be in my fstab file to mount on both sda3 and sda5?

I'm confused as to how the whole thing works

thisoldman · 2011-01-22 00:08:11

Would you please post the commands you entered when you attempted to mount sda1?

Does this show that /dev/sda1 exists?

$ ls /dev/sda1

If sda1 can't be seen, the message returned by the above command will be

ls: cannot access /dev/sda1: No such file or directory

Next, please show us your current partition table. You'll have to run this command with root privileges:

# fdisk -l /dev/sda

Madbunny · 2011-01-22 00:46:00

output of fdisk -l /dev/sda

Last login: Sat Jan 22 10:16:56 2011 from desktop
[brian@htpc ~]$ sudo fdisk -l /dev/sda1

Disk /dev/sda1: 24 MB, 24643584 bytes
255 heads, 63 sectors/track, 2 cylinders, total 48132 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

     Device Boot      Start         End      Blocks   Id  System
[brian@htpc ~]$

Output of ls /dev/sda

/dev/sda

I tried mounting it this way:

mount -t ext2 /dev/sda1 /mnt/sda1

substituting ext2 with ext3,ext4 etc but it keeps saying wrong filesystem.

thisoldman · 2011-01-22 01:18:18

@Madbunny, I was hoping to see the whole partition table, that's why i asked for 'fdisk -l /dev/sda, not 'fdisk -l /dev/sda1'. That would give a clue as to the

If the directory '/mnt/sda1' exists, and sda1 contains a common filesystem, 'mount' should recognize the filesystem type without the need for the '-t' option.

That is, 'ls /mnt' should list 'sda1'. Then the command 'sudo mount /dev/sda1 /mnt/sda1' would just work without specifying the filesystem.

I'm puzzled by the return from 'fdisk -l /dev/sda1' on your machine. There should be a message that /dev/sda1 doesn't contain a valid partition table. But at least we know sda1 and sda5 exist.

Madbunny · 2011-01-22 04:18:59

thisoldman wrote:

@Madbunny, I was hoping to see the whole partition table, that's why i asked for 'fdisk -l /dev/sda, not 'fdisk -l /dev/sda1'. That would give a clue as to the
If the directory '/mnt/sda1' exists, and sda1 contains a common filesystem, 'mount' should recognize the filesystem type without the need for the '-t' option.
That is, 'ls /mnt' should list 'sda1'. Then the command 'sudo mount /dev/sda1 /mnt/sda1' would just work without specifying the filesystem.
I'm puzzled by the return from 'fdisk -l /dev/sda1' on your machine. There should be a message that /dev/sda1 doesn't contain a valid partition table. But at least we know sda1 and sda5 exist.

Sorry, misread it.

sudo fdisk -l /dev/sda

[brian@htpc ~]$ sudo fdisk -l /dev/sda

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63       48194       24066   83  Linux
/dev/sda2           48195     3951989     1951897+  82  Linux swap / Solaris
/dev/sda3         3951990    43022069    19535040   83  Linux
/dev/sda4        43022070  1953520064   955248997+   5  Extended
/dev/sda5        43022196    82092149    19534977   83  Linux
/dev/sda6        82092213  1953520064   935713926   8e  Linux LVM

Trying to mount /dev/sda1

[brian@htpc ~]$ sudo mkdir /mnt/sda1
[brian@htpc ~]$ sudo mount /dev/sda1 /mnt/sda1
mount: you must specify the filesystem type
[brian@htpc ~]$

I set this machine up 6 months ago but remember setting up the sda1 partition for /boot to reside there. That way I could edit the menu.lst file from within sda3 and sda5 as /boot would be mounted in each of their fstabs.

stryder · 2011-01-22 07:09:40

I would hazard a guess that sda1 is not formatted, /boot is on your root partition. Whatever you might have remembered, /boot is not in your fstab. And since grub is reading the menu.lst on sda3 it can't be configured to sda1.

Madbunny · 2011-01-22 07:40:57

stryder wrote:

I would hazard a guess that sda1 is not formatted, /boot is on your root partition. Whatever you might have remembered, /boot is not in your fstab. And since grub is reading the menu.lst on sda3 it can't be configured to sda1.

/boot is not in my fstab, I said that was what I intended to do when I first set this all up.

I think I have worked out what to do now.

One question though, at what stage of the setup process would I have instructed /boot to mount on root sda3?

Last edited by Madbunny (2011-01-22 07:53:12)

Varg · 2011-01-22 09:22:06

When you are setting the mount points make sure that you assign /boot to sda1.
During configuration add /boot to fstab.
And at the end, install grub to sda, not sda1 or sda3. Set the menu.lst like this:

title Arch Linux
root (hd0,0)
kernel /vmlinuz26 root=/dev/sda3 ro
initrd /kernel26.img

Madbunny · 2011-01-24 20:05:40

Varg wrote:

When you are setting the mount points make sure that you assign /boot to sda1.
During configuration add /boot to fstab.
And at the end, install grub to sda, not sda1 or sda3. Set the menu.lst like this:
title Arch Linux
root (hd0,0)
kernel /vmlinuz26 root=/dev/sda3 ro
initrd /kernel26.img

Just curious, don't I need to do anything to instruct grub to read menu.lst off sda1 as opposed to sda3? At the moment it reads the menu.lst file off sda3.

I thought I'd have to do a root(0,0) at the grub command prompt.

Arch Linux

#1 2011-01-21 09:59:31

[SOLVED] Grub Confusion

#2 2011-01-21 11:13:51

Re: [SOLVED] Grub Confusion

#3 2011-01-21 12:29:44

Re: [SOLVED] Grub Confusion

#4 2011-01-21 12:36:41

Re: [SOLVED] Grub Confusion

#5 2011-01-21 12:55:47

Re: [SOLVED] Grub Confusion

#6 2011-01-21 13:11:42

Re: [SOLVED] Grub Confusion

#7 2011-01-21 22:07:48

Re: [SOLVED] Grub Confusion

#8 2011-01-22 00:08:11

Re: [SOLVED] Grub Confusion

#9 2011-01-22 00:46:00

Re: [SOLVED] Grub Confusion

#10 2011-01-22 01:18:18

Re: [SOLVED] Grub Confusion

#11 2011-01-22 04:18:59

Re: [SOLVED] Grub Confusion

#12 2011-01-22 07:09:40

Re: [SOLVED] Grub Confusion

#13 2011-01-22 07:40:57

Re: [SOLVED] Grub Confusion

#14 2011-01-22 09:22:06

Re: [SOLVED] Grub Confusion

#15 2011-01-24 20:05:40

Re: [SOLVED] Grub Confusion

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