grub fails to installon dev/mapper

[Eve Lee]

Hello,

I'm trying to install Ubuntu 12.04 64bit on Sony Vaio Z131A2JL alongside Windows 7.
I've created a partition of free space for Ubuntu on Windows first then created 4 partitions (/boot, /, /home, and swap)
using the Ubuntu installer on /dev/mapper (I saw that tutorials mention /dev/sda but this was not in the option for me).

The installer then failed with an error message

"Unable to install GRUB in /dev/mapper. Executing grub-install /dev/mapper failed. This is a fatal error."

I've tried installing GRUB on the /boot partition specifically but this failed as well.

Please let me know what I can do to have this fixed.

Best Regards,

E.L.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.10.16
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu5
Architecture: amd64
CasperVersion: 1.315
Date: Sat Jul 28 01:16:21 2012
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
ProcEnviron:
 LANGUAGE=en_CA.UTF-8
 TERM=unknown
 PATH=(custom, no user)
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Rsus (rsus)]

In lenovo z860, i used gparted standalone from dvd to create multiple partitions.
Ntfs ones were then used to install win 7 professional 64 bit.
then in remaining 1 partition i created extended partiation (not starting in logical/some boundary), within which i created boot, root, user and swap partitions.
Then used current lts ubuntu installer from dvd and after it got all the details from me, during install of grub, it failed with error that could not install and so the boot would not work, and took me through bug reporting.
I am stuck and really want to start using ubuntu.
pls help.

[Eve Lee (lapleinelune)]

I had to use the alternative Ubuntu installer to enable ata raid, then everything worked smoothly using just 2 partitions (ext4 and swap) created by MiniTool Partition Wizard from Windows (although I had to reformat my swap partition using the Ubuntu installer). It seems like this is not an option in the standard installer.