Hey where did /3GB go in Longhorn and Vista?

re: Hey where did /3GB go in Longhorn and Vista?

Abdul Rahiman — Sat, 18 Nov 2006 22:18:35 GMT

I knew that there is no boot.ini file in Longhorn, however reading your blog raised a basic question..how about booting in DSRM and so? Above you explained that for booting in dsrm mode we can modify the boot.ini. How do we do that in Longhorn?

And ahh your blogs are damn useful..thanks.

Working in DCOPSESC-MS IT.

re: Hey where did /3GB go in Longhorn and Vista?

Brad Rutkowski — Tue, 05 Dec 2006 01:40:02 GMT

To boot into DSRM in Longhorn use MSCONFIG. It's under the safe boot options.

re: Hey where did /3GB go in Longhorn and Vista?

Todd — Wed, 20 Dec 2006 20:22:01 GMT

Brad-

Thanks for this post! Can you recommend what configuraton I should use on a Vista laptop w/ 4GB of RAM running: Vista 32-bit, Office 2007, Virtual PC/Virtual Server, IE, etc...

My main concern is will system services have enough memory to run well (e.g., SuperFetch).

Thanks!

re: Hey where did /3GB go in Longhorn and Vista?

Brad Rutkowski — Thu, 21 Dec 2006 01:48:37 GMT

I'd say just stick with the default of 2GB for Usermode and 2GB for Kernel.

The only real reason to use 3GB is if you have an application that can take advantage of it, like a small SQL database or domain controller.

If you find that virtual server is consuming a lot of usermode space then you could increase the USerVA space as much as you need.

re: Hey where did /3GB go in Longhorn and Vista?

chico — Tue, 30 Jan 2007 20:16:06 GMT

When I run BCDEDIT... I get the following error. The boot configuration data store could not be opened. Access is denied.

Any suggestions?

re: Hey where did /3GB go in Longhorn and Vista?

CHICO — Tue, 30 Jan 2007 20:58:32 GMT

I figured out my problem. But how do I verify the switch has worked?

re: Hey where did /3GB go in Longhorn and Vista?

Brad Rutkowski — Wed, 31 Jan 2007 21:20:24 GMT

I imagine you were'nt running the bcdedit command via an elevated cmd prompt? :)

For verification just type BCDEDIT at the cmd prompt and you should see the increaseuserva value listed. If you want to know how to verify from the debugger than thats a differnet story.

re: Hey where did /3GB go in Longhorn and Vista?

chico — Thu, 01 Feb 2007 22:05:37 GMT

Thanks Brad for your help! It's all working beautifully. Now, let's say I need to remove or reset the switch (ie. get rid of increaseuserva when I go to BCDEDIT). How would I do this? I have a machine that I tested this on but now I need to get it back to the state it was in before I started tinkering with it.

Thanks.

re: Hey where did /3GB go in Longhorn and Vista?

Jack van Kinsbergen — Wed, 07 Feb 2007 01:33:44 GMT

Brad:

I have the following situation:

1. 4GB Asus P5W DH mother board.

2. AMI Bios recognizes the 4GB

3. WinXP recognizes the /3GB switch and ControlPanel=>System shows greater than 3GB

4. Installed Dual boot with Vista

5. Vista ControlPanel=>System shows 2 GB

5. Executed bcdedit /set IncreaseUserVa 3072 successfully

6. bcdedit now shows 3072 IncreaseUserVa

7. reboot and Vista ControlPanel=>System still shows 2 GB

8. MemWatch utility shows 2 GB as well.

9. Reboot shows XP now (without /3GB sw) at 2 GB.

10. Back to Vista=>bcdedit won't let me change the XP IncreaseUserVa.

Bottom line. 4GB installed and now neither XP or Vista recognizes greater than 2GB even though Bootstore says Vista IncreaseUserVa at 3072. Original XP used to recognize over 3GB,

What am I missing here?

re: Hey where did /3GB go in Longhorn and Vista?

AZSport — Thu, 05 Apr 2007 17:19:26 GMT

How do I delete the IncreaseUserVa entry once set?

re: Hey where did /3GB go in Longhorn and Vista?

Irvin Hayes — Thu, 05 Apr 2007 23:03:25 GMT

To delete the entry use the following.

bcdedit /deletevalue increaseuserva

re: Hey where did /3GB go in Longhorn and Vista?

AZSport — Sun, 08 Apr 2007 07:32:21 GMT

Worked great. Thanks Irvin.

re: Hey where did /3GB go in Longhorn and Vista?

ofek — Tue, 15 May 2007 22:23:44 GMT

i dont understand

what is BCDEDIT

is it a program????

re: Hey where did /3GB go in Longhorn and Vista?

Brad Rutkowski — Wed, 16 May 2007 23:32:42 GMT

Hey Ofek, here is your answer:

http://technet2.microsoft.com/WindowsVista/en/library/85cd5efe-c349-427c-b035-c2719d4af7781033.mspx?mfr=true

And yes it is an exe:

C:\Windows\System32\bcdedit.exe

re: Hey where did /3GB go in Longhorn and Vista?

Eduardo Salvio — Sat, 15 Sep 2007 20:49:44 GMT

Brad,

I used bcdedit, checked through cmd and it's there; however, it does not show on task manager 4gb. I am using an Intel DQ965GF with latest bios updated.

could you help what I should be doing wrong?

re: Hey where did /3GB go in Longhorn and Vista?

Brad Rutkowski — Mon, 17 Sep 2007 20:30:21 GMT

Eduardo, the /3GB switchdoes not increase the physical memory that the OS can see it just splits the virtual memory up so that user mode prcoesses see 3GB of the VM space. If you are having issues seeing all the RAM in your system, I'd check some of the forums on the internet for your desktop model.

-Brad

re: Hey where did /3GB go in Longhorn and Vista?

JonBlok — Tue, 05 Feb 2008 14:15:44 GMT

Thank you Brad for your patience and solid information

re: Hey where did /3GB go in Longhorn and Vista?

sharon — Sun, 27 Apr 2008 02:21:34 GMT

My 4G only read as 3 on a 32 bit Vista...common situ, I see...when I run BCDEDIT I get: The boot configuration data store could not be opened. Access is denied.

You mentioned in a prior post running that from "elevated" command prompt...admit I'm clueless in this arena...help?

Thanks...

re: Hey where did /3GB go in Longhorn and Vista?

Brad Rutkowski — Tue, 29 Apr 2008 00:59:50 GMT

Hey Sharon, just find the command prompt link in the start menu and alt-click and choose "run as administrator"

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re: Hey where did /3GB go in Longhorn and Vista?

raiden I — Sun, 07 Jun 2009 11:06:27 GMT

should this work with 8GO RAM ??

i mean could i take full advantage of 8go ram installed ???

re: Hey where did /3GB go in Longhorn and Vista?

Brad Rutkowski — Wed, 10 Jun 2009 20:04:28 GMT

Hi Raiden, to take advantage of that much RAM you should use an x64 OS. The 3GB switch is for x86 systems, and wouldn't help with a situation where you want to use 8GBs.

re: Hey where did /3GB go in Longhorn and Vista?

Lawrence Berger — Mon, 07 Sep 2009 20:01:21 GMT

I am unable to use bcdedit I get permishion denied I am the Admin? Tried C: c:windows

c:windows/boot

Vista 32

Larry