RAM upgrade 2Gig to 4Gig Freezes existing multiple Vboxes

Popovitch · Post by **Popovitch** » 27. Sep 2008, 07:25

Hello.

I've upgraded from 2Gig to 4Gig ram and when I run 2 Virtualbox machines that nomally run without problem, they both freeze (debian etch stable, ubuntu hardy 8.041).

Ubuntu Hardy 8.041 is the host, all updates current.

Question;
Will a change in host pysical RAM (increase) affect running previously
created Vbox machines?

Thank you.
PV

pete_l · Post by **pete_l** » 27. Sep 2008, 17:07

I had a similar experience with Ubuntu 8.0.4 on an AMD 64 box.
I upgraded from 2*1GB memory sticks to 4*1GB (the original 2,
and 2 extra). After that I got random crashes / lockups with VB
guests.
It turned out there were two things wrong. These problems only
manifested themselves when I started to exercise the additional RAM.
First of all, the network driver for my motherboard's 100bT ethernet
wasn't (still isn't) very good and caused crashes when the BIOS
was configured to see the whole 4GB of RAM.
Changing the BIOS settings so I effectively removed a few hundred
MB helped a bit, but the machine was still flakey. More investigations
led me to the conclusion that a lot of motherboards say they
support 4GB, but in reality are only good up to 3GB. The reason
being that Microsoft can only use 3GB, so they think they're safe
advertising 4GB, in the knowledge that only us freaks would bother
loading the full amount - windows users would stop at 3GB and so
would never see any problems (to be fair, they may well say that
only microsoft is "supported" on their MBs).

Popovitch · Post by **Popovitch** » 27. Sep 2008, 18:05

pete_I,

Did you solve the freezes entirely?

If you changed the bios back to accept the 3 Gig maximum Ram did it stop virtualbox from crashing?

Also, is it irrelevant if you create the Virtualbox 'before/after' upgrading more RAM ?

Thank you.

Post by **Sasquatch** » 27. Sep 2008, 19:58

You can try to run the 'big mem kernel' on your system. That kernel is build to be able to allocate more than the limit of 3,5 GB of RAM. Else you need to run a 64 bit Host if you have a 64 bit CPU.

pete_l · Post by **pete_l** » 27. Sep 2008, 21:42

Popovitch wrote:pete_I,
Did you solve the freezes entirely?

Yes.
( should say this is an AMD_64 system running 64-bit Ubuntu)
What I did was drop back to 3GB of memory (my original 2*1GB sticks
and swapped out the extra 2*1GB - replaced them with 2*512MB)
It's still better than the 2GB I started with (didn't leave much
headroom with a decent-sized VB guest running) but I was
disappointed that I was not able to run Ubuntu with 4GB visible.
However with 3GB my system is rock solid.

Popovitch · Post by **Popovitch** » 28. Sep 2008, 15:30

Thanks pete_i, Sasquatch.

Do either of you know if this is true ?

Question;
Will 'any' change in host pysical RAM (increase) affect running previously
created Vbox machines? For example, 2 Gigs to 3 Gigs.

pete_l · Post by **pete_l** » 28. Sep 2008, 17:38

Popovitch wrote:Will 'any' change in host pysical RAM (increase) affect running previously created Vbox machines? For example, 2 Gigs to 3 Gigs.

Well, all the VB guests I had created for my 2GB system worked the
same with the extra RAM. There was one effect, they ran faster as the
box didn't have to page-out any memory when I had memory-
intensive (e.g. firefox: 500MB++) processes running on the host.
However, I didn't try increasing the amount of memory allocated to
the guests, (or the size of the video buffer) as they had sufficient for
my needs and weren't constrained by insufficient memory.

So yes, it is possible for changes to the host to affect the guests.
Since they all share resources (CPU - either single or multi, disks,
USB/network bandwidth, RAM) you can't say that the performance
- or stability of a guest will always be unaffected by changes made
to the underlying hardware.

Post by **stephanecharette** » 28. Sep 2008, 19:18

Popovitch wrote:Will 'any' change in host pysical RAM (increase) affect running previously created Vbox machines? For example, 2 Gigs to 3 Gigs.

I had a bucketload of VMs created back when I had 2G of ram. At Christmas (9 months ago) I received another 2G for a total of 4G. Haven't had any problems running any of the guests I created before -- they still run exactly the same. Only difference is I can run more of them before I run out of memory...

But the descriptions above about memory problems related to motherboard and/or bios issues is worrysome. I'm glad I haven't had to deal with hardware issues.

(Not only did they run the same -- but I had created my VMs when my host was 32-bit Ubuntu. When I received the extra ram, I backed up the VMs, formated my drive and installed 64-bit Ubuntu & 64-bit VirtualBox. Restored my VMs, and was glad to see they continued to work fine. VB should be glad to advertise binary compatibility between their 32-bit and 64-bit products, as it saved me *lots* of time re-installing all my VMs.)

Stéphane