[ubuntu-uk] dual boot problem

Liam Proven lproven at gmail.com
Mon May 14 12:41:46 UTC 2012

On 13 May 2012 21:20, Barry Drake <ubuntu-advertising at gmx.com> wrote:
> On 13/05/12 21:03, Bill Baker wrote:
>> Norman, please wait for further advice before trying my suggestion; but if
>> this was my machine I would now boot directly to Ubuntu from the live CD &
>> from there I would try "grub-install /dev/sda" [or sdx where x is the boot
>> drive] from a terminal. However, *please* do wait for my idea to confirmed
>> as good or rubbish before doing anything [it may not work with your set-up].
>> It is not my machine - it is yours & as such, deserves a 2nd opinion ;)
> Maybe that on its own might work; the full sequence might be necessary.  It
> depends so much on where grub is - and it must be on the drive that Noman is
> booting from.  And this drive must be mounted first at a known mountpoint.
> Re-install grub from live-CD
> sudo -i
> mount /dev/sda2 /mnt #assuming that Ubuntu is on sda2 - check with gparted
> #mount /dev/sda3 /mnt/boot  #skip this one if not have a separate /boot
> partition
> grub-install --root-directory=/mnt/ /dev/sda
> Then update-grub to complete.
> The first step is usually need to access the drive.  If it is mounted
> already and you know where it is mounted, you can use this as an
> alternative.
> Any third opinion?

That is true and correct, AFAICS, but to be honest, it would probably
be easier just to reinstall.

Norman: at a minimum, you need 2 partitions. I suggest you shrink the
Windows partition by about half and use the rest of the space for an
Extended partition.

In there, you put the Linux logical drives.

As a minimum:

/  - also known as the root partion.
swap - which Linux uses for virtual memory. Make this twice as much as
the physical RAM in your computer and put it on the end of the drive.

Better still is to have root, home and swap, in which case you give
say 16GB to root, 2x RAM to swap and all the rest to /home. This makes
it much easier to back up, dual-boot multiple distros, wipe and
reinstall distros and so on.

When it asks where to install GRUB, tell it to use the main hard disk,
not a partition.

Before you launch the installer, boot to the desktop - pick "Try
Ubuntu" - and then run GParted.

So let's say you had 2 drives. They'd be:

Assume we're leaving sdb alone. It probably contains a Windows
partition, sdb1. Ignore this for now.

On sda1, shrink the Windows partition to half its size.

In the remaining space, create sda2 as an Extended partition.

In there, create sda5 for root, say 16GB, using ext4, then sda6 for
/home, all the remaining space less twice your physical RAM, also
ext4, and then at the end, sda7 for swap.

Now, save your changes and quit Gparted.

Then run the installer. When it asks what to do, pick "something
different" and do a custom install. Choose sda5 as the partition for /
followed by sda6 as the partition for /home and sda7 as the partition
for swap. If you formatted them in Gparted, you don't need to format
them again now, so untick the "format" box.

It should suggest installing Grub to /dev/sda - in other words, the
whole drive. This is what you want. Leave it alone. If it does not,
for some reason, pick /dev/sda as the destination for the GRUB
bootloader. This will enable you to choose between Linux and Windows
at power-on.

Liam Proven • Profile: http://lproven.livejournal.com/profile
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