joe
Mon, 06 Dec 2004 16:38:55 -0800
/3GB is very popular on servers in enterprise spaces such as large Exchange servers and large SQL Servers and Domain Controllers. It is a combination of a bit flip in the PE info of the image and the app properly using the additional 1GB of space allocated to it. As I alluded to previously there have been apps that have flipped that switch but because they were using certain forms of addressing (various relative addressing formats) they had very odd app blowups. Also as mentioned by ~Eric and myself, you can see issues with kernel space being reduced to 1GB causing issues as well. ~Eric made great points that I forgot that specifically you could suffer around free PTE's and non-paged pool. Free PTE's is a specifically mentioned issue when doing this with Exchange servers and you are generally recommended to look at increasing the number of systempages via registry modification (though this decreases paged pool memory by whatever amount you increase the size of the PTE Pool which can also impact perf). joe -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paul van Geldrop Sent: Monday, December 06, 2004 5:21 PM To: [EMAIL PROTECTED] Subject: RE: [ActiveDir] Stress testing and performance analysis of domain controllers Unless memory is not serving me well (pardon the bad pun), the switch doesn't actually do that much. In normal operating mode, the virtual address space of, let's say, a 4 GB machine is split up in 2 blocks, both 2 GB large. When using the 3GB switch, the virtual address space that is used for user mode is expanded to 3GB, while the virtual address space for the kernel is sized to 1 GB. That, I believe, is all there is to it. I believe Linux does the same by default. However! I believe that the applications using this space must have some little funky bit set to properly use the space allocated.. that might explain the apprehension from the MS side to support this.. after all, that'd make them dependant on 3rd party software parties to incorporate this feature. I might be wrong, it's been a while since I actually looked into any interesting programming stuff, let alone stuff that'd use this kind of address space. :) Of course, running SQL/Exchange/Oracle/etc/etc with a large load might make it interesting to flip this switch. I even recall seeing this setting recommended for an MS product, though I can't recall for the life of me which app that was.. I can see the more recent article making more sense in this aspect, especially regarding the kernel space reduction in higher loads. Regards, Paul. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jorge de Almeida Pinto Sent: Monday, December 06, 2004 10:14 PM To: 'Renouf, Phil '; '[EMAIL PROTECTED] '; '[EMAIL PROTECTED] ' Subject: RE: [ActiveDir] Stress testing and performance analysis of domain controllers Now this is fun: According to MS-KBQ291988 (http://support.microsoft.com/kb/291988) QUOTE: Caution The /3GB switch in Windows Server 2003, Standard Edition is only for development and testing purposes. Microsoft does not support using the /3GB switch in Windows Server 2003, Standard Edition in a production environment. The /3GB switch can cause some applications to have problems that are related to address dependencies or to a reduction in kernel space. According to MS-KBQ308356 (http://support.microsoft.com/?id=308356) QUOTE: If you plan to use more than 1 GB of physical memory on the domain controller, use Windows 2000 Advanced Server, Windows 2000 Datacenter Server, Windows Server 2003, Standard Edition, Windows Server 2003, Enterprise Edition, or Windows Server 2003, Datacenter Edition. You can use the /3GB switch in the %SystemDrive%\Boot.ini file on these versions of Windows to provide an additional 1 GB of addressable memory. However, if you use this switch with Windows 2000 Server, this memory space is marked as unavailable. For additional information about memory configuration tuning, click the following article number to view the article in the Microsoft Knowledge Base: 291988 A description of the 4 GB RAM tuning feature and the Physical Address Extension switch According to "W2K3 Deployment Kit - Designing and Deploying Directory and Security Services" Chapter 4 "Planning Domain Controller Capacity" QUOTE: Note The /3GB switch can be added to domain controllers that are running Windows Server 2003, Standard Edition; Windows Server 2003, Enterprise Edition; and Windows Server 2003, Datacenter Edition. Do not add the /3GB switch to the Boot.ini file if you have less than 2 GB of physical memory. Very nice.... 2 different statements according to the /3GB switch Does any one know which one is true? Personally I think MS-KBQ291988 is correct because of the date of the article -> 15 nov 2004 Regards, Jorge -----Original Message----- From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: 12/6/2004 6:12 PM Subject: RE: [ActiveDir] Stress testing and performance analysis of domain controllers You don't need the /3GB switch for a DC. Just having more than 2GB of ram does not require using the /3GB switch, systems like Exchange require it, but a DC shouldn't need it. Phil -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ruston, Neil Sent: Monday, December 06, 2004 11:57 AM To: '[EMAIL PROTECTED]' Subject: [ActiveDir] Stress testing and performance analysis of domain controllers As part of a more general AD design refresh, I am re-visiting the DC hardware and OS configuration. I am proposing several changes to the DC spec, including the adoption of the following: * Use 4Gb RAM * Use /3gb switch * Place AD logs and database on separate disk spindles In order to 'sell' this idea, I would like to demonstrate the effective increase in 'horse power' that the above offers. I am therefore looking for a tool which can help me to show that a DC with config A can handle load x whilst DC spec B can handle load y. Ideally, this tool will act much like loadsim and simulate a load on the DC so as to identify the maximum load that each config is capable of handling. Is there such a tool available on the market? Thanks in advance, Neil Neil Ruston - MVP Directory Services ======================================================================== ====== This message is for the sole use of the intended recipient. If you received this message in error please delete it and notify us. If this message was misdirected, CSFB does not waive any confidentiality or privilege. CSFB retains and monitors electronic communications sent through its network. Instructions transmitted over this system are not binding on CSFB until they are confirmed by us. Message transmission is not guaranteed to be secure. ======================================================================== ====== List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ This e-mail and any attachment is for authorised use by the intended recipient(s) only. It may contain proprietary material, confidential information and/or be subject to legal privilege. It should not be copied, disclosed to, retained or used by, any other party. If you are not an intended recipient then please promptly delete this e-mail and any attachment and all copies and inform the sender. Thank you. List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/ List info : http://www.activedir.org/mail_list.htm List FAQ : http://www.activedir.org/list_faq.htm List archive: http://www.mail-archive.com/activedir%40mail.activedir.org/