SQL Server Performance

DL380-G4, 4 GB of RAM and SQL 2000 HELP!!

Discussion in 'Performance Tuning for Hardware Configurations' started by gambler1025, Mar 12, 2007.

  1. gambler1025 New Member

    OK, I have a DL-380 G4 with 4 GB of RAM installed, Windows 2003 Enterprise and SQL 2000 Enterprise. Only 3.5 GB is visible to Windows 2003 because the PCI Express is eating up 512 MB. There is a System ROM update from HP that remaps the lost 512 above 4 GB. But according to HP you have to use the /PAE switch in order for that remapped memory to be used. However they recommend not doing this with 4 GB installed due to performance reasons!! This is quite the catch 22.

    I'd really like to enable the /3 GB switch so I can have 3 GB available for the application.
    But I dont want to kill perfomance with the PAE switch. I also dont want to enable the 3 GB switch with only 3.5 GB visible and leave only 512 MB for the OS. Has anyone out there run into this issue? What do you recommend I do? Thanks
  2. joechang New Member

    no. pci-e is not eating your memory
    if you open the box, its still there, undigested

    the os only sees 3.5G because its using the old memory management methods

    pae kicks in the new one that can see >4GB and the full original 4G

    there is nothing wrong with using /3GB w/o PAE
    people do it all the time

    do worry about this
    you are confusing physical memory concepts with virtual address space concepts
    which is a rather complex subject

    just flip the /3GB switch and stop worrying
    of course, you do need to test your app for good behavior, which is a difference matter
  3. gambler1025 New Member

  4. joechang New Member

    jeez, even the persons who wrote the HP and MS articles were confusing physical memory and virtual address space concepts

    they are also confusing PAE with AWE, PAE uses 8 byte PTE, vs 4 byte for the original windows memory manager, which add some overhead, but the real overhead is from AWE, which you will not be using

    userenv? i am not familiar with this
    with the /3GB, there is the /USERVA option
    is that what you meant?

    anyways
    for dedicated SQL, 3.5G physical memory & /3GB is fine

    however, there are issues with using /3GB on W2K3 unrelated to this reduced physical memory we are discussing
    you must test the stability of your app with /3GB
    and it is a virtual address space problem, not phyical memory

    test carefully

  5. gambler1025 New Member

  6. joechang New Member

    its your system
    who is going to be blamed if something goes wrong

    always test
    always let your boss know in writing/email
    wait for the reply
  7. DBADave New Member

    Hi Joe,

    I was reading your comments in this link and have a followup question regarding the 512MB not being reporting by the OS. I have a database server running Windows Server 2003 SE with 4GB of memory. The BIOS setting is as follows:

    /fastdetect /NoExecute=OptOut /3GB /Userva=2950

    I'm not using PAE and from what I can understand this is the reason the server is only reporting 3.5GB of memory. I was originally told that using the /3GB switch restricts the OS to only 1GB of memory for the kernel vs. the standard 2GB. However, based upon this thread and other information is my OS only able to access 634MB? 4096MB - 512MB (as discussed in the Microsoft link) - 2950MB (from Userva setting above). Is this correct? If so, is it worth it to enable PAE? I don't believe PAE would negatively impact SQL Server from what I've read, however I don't know what it would do to Trend Anti Virus, CSA, RSA, etc...

    Thanks Joe,

    Dave
  8. joechang New Member

    1. Virtual Address Space
    2. Physical Memory

    are different concepts,
    /3GB controller VAS,
    3.5GB is the physical memory available to your system

    i do not see what you will gain from using /PAE, or lose for that matter,
    ie, there will probably not be much of a difference

    my understanding is /3GB and /USERVA are not supposed to be used together
    but i didn't exactly read the instructions on this
  9. DBADave New Member

    I think I've got it now.

    (1) Virtual Address Space (VAS) is 4GB for a 32-bit OS regardless of the size of your physical memory

    (2) 2GB of the 4GB VAS is reserved by default for the kernel and the other 2GB for user address space.

    (3) All processes in the kernel space share the same 2GB

    (4) Using /3GB reduces the size of the kernel portion of the VAS to 1GB and increases the application side to 3GB

    (5) /USERVA applies to Windows Server 2003 and Windows XP and allows you to specify a user address space between 2GB and 3GB.

    (6) Using /PAE allows the operating system to access additional memory beyond 4 GB. This means more physical memory can be mapped into the application#%92s virtual address space.

    (7) PCI devices use up additional memory, which is then unavailable to be used by the operating system. The missing 512 MB of memory appears to be the result of PCI Express, where 256 MB block of memory is allocated to the PCI Extended Configuration space, and PCI cards, where 256 MB is allocated to memory regions

    If the above is correct, then just out of curiosity...

    (1) How can adding /PAE recapture the 512 MB from item #7 above?
    (2) Why is this only an issue when exactly 512 MB of memory is installed?

    Thanks, Dave
  10. joechang New Member

    wow, you did some reading
    i absolutely despise reading instructions
    i like to tell other people to read instructions and then brief me (to prove that they read it)

    my understanding of this is the PCI stuff maps physical memory addresses in the 3.5-4.0GB range
    normally, the system/BIOS just accepts this, ignoring the physical memory there,

    flipping the /PAE tells the OS to remap physical memory in that range to another location (address wise)

    i say it is my understanding because the documentation for this is rather thick, so i deemed it proper to instruct some one else to read it
  11. DBADave New Member

    Joe I feel so used, duped into reading pages upon pages of mind-numbing techno-babble. I blame you for the headache it gave me on Friday. At least it made my train ride to work pass by quicker.

    I must be a bit insane because in a strange way the information was somewhat interesting.

    Thanks again,

    Dave
  12. joechang New Member

    in turn, you will instruct the next generation to read the available material on a subject, then come brief you to prove that they did their homework

    eventually, the smarter ones will figure out why they are really briefing you
    such is cruel nature of work

    yes, you are more than a bit insane,
    in the next stage, your wife/girlfriend will tell you that you have lost interest in her and she wants a divorce

    i suggest you consult your companies health insurance policy to see what is covered
    is a pyscharist or bartender expenses reimbursible?
    if prefer the second, more professional,
    tell your company that the second is also much less expensive
  13. DBADave New Member

    The process sounds a bit like a chain letter, only substituting a letter with "research". <br /><br />I may be in luck. One of our server administrators moonlights as a bartender. I'm sure he could give me a "company" discount, which would make this option even more appealing. <br /><br />I can see now. I become more and more engrossed in researching mind-numbing SQL facts and theories that my wife leaves me. I become dependent upon alcohol in an attempt to be at peace with myself and slowly develop a receding hairline from the act of constantly slapping my forehead after reading the research of those who have fallen before me. Then, just as I begin to believe I actually understand my role in life, someone in Microsoft#%92s marketing department sees an opportunity to make more $$$$ by pitching the idea of a single computer servicing all requests generated by something known as a “terminal”. The idea of making the terminal screen appear in green rather then allowing multi-colored options seams appealing. Afterall green is a calming color. Something known as JCL can then be used to prepare a person#%92s code for execution, which for simplicity-sake they#%92ll call MOBOL (Microsoft#%92s Original Business Oriented Language). Of course data storage will need to change and the idea of linked-lists will be presented and a proposal for a Queued Sequential Access Method and an Indexed Sequential Access Method will be met with joy in Redmond. Microsoft can also see the benefits of a new licensing model and before you know it I#%92m back in the bar explaining to someone named Joe how life was much simpler when I was a kid. [<img src='/community/emoticons/emotion-1.gif' alt=':)' />]<br /><br />Off to do more research.<br /><br />Dave<br /><br />
  14. satya Moderator

    LOL guys, [<img src='/community/emoticons/emotion-1.gif' alt=':)' />] much insight for a newbie from your experience.<br /><br /><b>Satya SKJ</b><br />Microsoft SQL Server MVP<br />Writer, Contributing Editor & Moderator<br /<a target="_blank" href=http://www.SQL-Server-Performance.Com>http://www.SQL-Server-Performance.Com</a><br /><center><font color="teal"><font size="1">This posting is provided AS IS with no rights for the sake of <i>knowledge sharing. <hr noshade size="1">Knowledge is of two kinds. We know a subject ourselves or we know where we can find information on it.</i></font id="size1"></font id="teal"></center>

Share This Page