Ubuntu 9.04 - ISO Integrity Error When VT-X Is Enabled

[quad65]

Hi,

I have both tried this with 9.04 RC and 9.04 which come out today. When I mount this ISO's with VT-X enabled, I select "check CD for defects" and it found 1 error. When I disable VT-X and check CD for defects, no errors.

Do you have any idea why this might be happening?

Thanks in advance.

(Using Virtualbox 2.2.0, I have AMD X2 4800+ processor)

[Perryg]

Check to see that VT-X is enabled in your bios?

[quad65]

Check to see that VT-X is enabled in your bios?

It's enabled.

BTW, I have some new information. When I try to install it while VT-X is enabled in VB, it progresses to %50-60 then gives an I/O error. While VT-X is disabled in VB, it is installed just fine.

[Perryg]

What is the error that it is telling you?
Also are you running this test because the MD5 checksum failed?
Have you actually tried to install and it failed?
Are you running this as an ISO file from disk or did you first burn it to CD? If burning to CD burn at a slower speed.

[quad65]

MD5 is fine.

ISO is on the disk.

I have edited my post above. Answer to your question about installation is there.

As I said before, it gives an I/O error. I'll reproduce it and write the exact message.

[quad65]

Alright,

When copying begins, it gives a "following file did not match its source copy on CD" error. It happened at ~%28 before, now it happened at %43. I select "retry" and installation continues. Same window sometimes comes up again and again but installation still progresses. Then comes I/O Error, which you can do nothing about and installation aborts. Here is that error: (Errno5)

[Perryg]

Sorry to ask so many questions but this was not provided to begin with.
Did you download the 64 bit version of Ubuntu?
Also I have seen that some people need to update their bios to make things work smoothly.

[quad65]

No, it is 32 bit.

I forgot to write those that you asked. So, it is only normal that you ask that questions. Thanks for your interest.

I should try updating my BIOS. But please note that OpenSolaris 11 is installed without a hassle when VT-X is enabled. So, I think it may not be related to BIOS at all.

[Perryg]

You should not turn on the VT-x switch when using a 32 bit OS guest. Even if Solaris is working it can produce nasty results later. So by design VBox is working as it should. Leave the switch off and install.

[quad65]

Interesting, I checked VirtualBox help and it says:

Prior to version 2.2, software virtualization was the default; starting with version 2.2, VirtualBox will enable hardware virtualization by default for new virtual machines that you create.

Enabling hardware virtualization is required only in two scenarios:

for certain rare guest operating systems like OS/2 that make use of very esoteric processor instructions that are not supported with our software virtualization and

if you want to run 64-bit guest operating systems (a feature added with VirtualBox 2.0), since most 64-bit CPUs ship with hardware virtualization anyway. The exceptions to this rule are e.g. older Intel Celeron and AMD Opteron CPUs.

Don't you think there is a contradiction? If it comes enabled by default then why is there a problem with 32-bit operating systems? And if it is only needed when I want to run 64-bit guest OS, why is it enabled when I install a 32-bit OS?

Also, there are two presets for Ubuntu: 32 bit and 64 bit. Since virtualization should only be used with 64-bit OS, why does VB still enable it when I select Ubuntu, not Ubuntu 64-bit?

I'm sorry if I asked the same thing twice, I'm a bit frustrated.

Edit: Should I use 64-bit with VT-X or 32-bit without VT-X when looking from performance point of view?

[Perryg]

You are not alone in your frustration. VB 2.2 is supposed to detect if you have a 64 bit OS and that it supports visualization. If it does it turns on the bit.
I have found that this is not always the case. Call it a glitch, or what ever you want, but the bottom line here if you are receiving errors look at the bit rate of the guest and matching accordingly in VBox will usually solve your problems.

[quad65]

Thank you for your explanation.

Can you answer this last one too, please?

Should I use 64-bit with VT-X or 32-bit without VT-X when looking from performance point of view?

[Perryg]

Thank you for your explanation.

Can you answer this last one too, please?

Should I use 64-bit with VT-X or 32-bit without VT-X when looking from performance point of view?

In VBox I have found that the rule of thumb is to use 64 bit with 64 bit, and 32 with 32. I do not know of a performance issue but compatibility can be an issue. While a 32 bit OS may load and work with VT-x on, crazy things can happen. I don't know if you are as lucky as I am but it never fails to bite me in the back side when I try to go out of the norm.

[quad65]

OK then, thank you very much for all your fast answers.