partitioning a RAID 0 drive

[Liam Proven]

On 6 September 2010 15:10, Tom H <tomh0665 at gmail.com> wrote:
> On Mon, Sep 6, 2010 at 6:59 AM, Liam Proven <lproven at gmail.com> wrote:
>> On 6 September 2010 02:33, Roy Lowrance <roy.lowrance at gmail.com> wrote:
>>> I'd like to install Ubuntu on my Windows 7 PC and dual boot.
>>>
>>> The PC has a RAID 0 card and I see one device and three subdevices in the
>>> Ubunut "Prepare partitions" dialogue:
>>> /dev/mapper/isw_dgijegbagg_RAIDVOL
>>>    /dev/mapper/isw_dgijegbaff_RAIDVOL1 type=ntfs, size =104MB
>>>    /dev/mapper/isw_dgijegbaff_RAIDVOL2 type=ntfs, size=1987802 MB
>>>    /dev/mapper/isw_ghijegbaff_RAIDVOL3 type=ntfs, size = 12485MB
>>>
>>> What I'd like to do is to split the 2 subdevice, the one with almost 2 GB of
>>> storage.
>>>
>>> I may also need a swap partition.
>>>
>>> How should I proceed?
>>
>> Don't.
>>
>> Dual-booting off a RAID is somewhere between "extremely difficult and
>> very dangerous" and "flat-out impossible".
>
> ???!!!
>
> Judging from the name of the raid partitions, this is fakeraid.

Exactly.

> If
> Ubuntu couldn't boot/dual-boot from it, there'd be a whole range of
> desktops on which Ubuntu couldn't be installed.

Beware. There is a *huge* difference between booting - which isn't a
problem - and dual-booting, which is a totally different kettle of
fish. You are conflating the 2.

> What I find worrying is someone wanting to use raid 0 for anything
> other than scratch data.

Agreed.

> I don't know the graphical installer that well but If you select
> raidvol2, don't you get an option to install Ubuntu alongside Windows?

The 2 OSs use totally different methods to create and manage RAID
arrays. If things go 1 sector out of perfect sync, I would expect one
OS to instantly trample all over the other's data.

> I would prefer to re-size the ntfs partition on raidvol2 and create
> partitions for Ubuntu while booted from a live cd. (Always make a full
> backup before partitioning and filesystem operations.)

> Also, it's 2 TB not 2 GB.

I didn't even get that far, but I did wonder about sharing 2GB of disk
between 2 21st-century OSs!

If the OP has 2 disks, better by far to use them as 2 disks, put
Windows on one and Linux on the other.

-- 
Liam Proven • Info & profile: http://www.google.com/profiles/lproven
Email: lproven at cix.co.uk • GMail/GoogleTalk/Orkut: lproven at gmail.com
Tel: +44 20-8685-0498 • Cell: +44 7939-087884 • Fax: + 44 870-9151419
AIM/Yahoo/Skype: liamproven • MSN: lproven at hotmail.com • ICQ: 73187508