Re: [Qemu-discuss] Qemu and hard drives >2TB

[Mike Lovell]

On 01/08/2012 02:30 PM, Christian Lerrahn wrote:
> I've used Qemu in the past to install NetBSD from a Linux system.
> However, the problem I'm facing now is that I need to install to a 3TB
> hard drive and Qemu will only recognise 2TB. Not only can I not used
> GPT but it never even sees the drive at its full size (which a non-gpt
> fdisk will).
>
> I've tried different versions of Qemu but possibly not the absolutely
> latest one. Is there any version that can handle a hard drive this size?

are you saying that the guest only sees a hard drive of 2TB even though 
the device on the host is 3TB? if that is the case, then it might be 
that you need to try a newer version of qemu. though, i did just try a 
simple test and was able to see a 3TB device in the guest using qemu-kvm 
0.12.5 that came with ubuntu 10.10 and with 1.0 compiled from source.

qemu should be able to see the full size of the disk. booting from it 
would be another question. i doubt seabios would have the ability to 
boot from something not using a mbr partition table. there are two 
potential options that i see but i have tried neither.

one would be to use a hybrid gpt/mbr partitioning configuration. gpt 
leaves the first block of a disk untouched and an mbr can be put in that 
space so its possible to have both mbr and gpt on a disk at once. 
gptsync is a tool that can read a gpt partition table and write the 
equivalent mbr to the same disk with a few limitations. maybe you could 
make a small partition at the beginning of the disk to boot off of and 
then use the remainder as a data volume. i don't know if netbsd supports 
hybrid gpt/mbr partition tables though so this may not even be an 
option. googling 'hybrid mbr' should provide more info.

the second option would be to try and use the uefi firmware that the 
tianocore project has for qemu. the subproject is called OVMF and 
http://sourceforge.net/apps/mediawiki/tianocore/index.php?title=How_to_run_OVMF 
has details about how to run that.

hopefully those give you a few things you could try to get this working. 
i've never used netbsd so i can't say how it will react to either of 
these nor have i spend enough time with either of these options to see 
that they work in other scenarios. but hopefully it will get you pointed 
somewhere where you can look to figure something out.

mike