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Don Burleson Blog 







VMware: Optimizing Windows

Oracle Tips by Burleson Consulting

As with Linux, it is safe to assume a virtual server host will have multiple processors and lots of memory, also most likely greater than 4 GB. Thus, you need to go with 64-bit Windows server editions unless you face some hardware driver issue that prevents this choice.

While I like Windows 2000 Server as much as the next guy and feel that it is a great candidate for being my virtual server host operating system, I nonetheless realize it is 7+ years old and getting a wee bit long in the tooth. Actually, the biggest problem is getting drivers for newer hardware on this platform. So Windows 2003 Server is really the only way to go and 64-bit Enterprise Edition Release 2 is the most highly recommended.

To improve I/O for file system based Oracle data files, Windows offers a little known and seldom used option that can yield between 50-150% performance improvements in standard database benchmarks like the TPC-C by simply changing the Windows registry setting as follows:

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Control\FileSystem\ NtfsDisableLastAccessUpdate=1

What this does is set the operating system to disable last access update for directories and files on this Windows server, which translates into radically reduced total I/O. Since the Oracle background processes are accessing the data files every 3 seconds and have their own headers with timestamps within them, why spend I/O resources to update time attributes for files or directories?

Some other common Windows registry tweaks for database servers include:

  • Disable 8 dot 3 Name Creation - This setting controls whether MS-DOS compatible 8.3 file names should be generated on NTFS partitions. Disabling this feature can increase the performance on high usage partitions that have large amount of files with long filenames. Setting this option also toggles whether to permit extended characters to be used in 8.3 filenames.

  • Enable a large size file system cache This entry controls whether the system maintains a standard size or a large size file system cache. Enabling a larger cache makes sense for networked database servers with sufficient memory.

  • Disable paging of the kernel code - This entry controls whether the user and kernel mode drivers and the kernel mode core system code itself can be paged. Disabling the paging of kernel code makes sense for database servers with sufficient memory.

  • IO Page Lock Limit - This entry controls the maximum amount of RAM that can be locked for I/O operations. The default minimizes RAM usage. An I/O intensive system could benefit from larger buffer sizes. Caution: setting this parameter too high can result in slower performance. Set it in increments and see how it affects your system

And whose corresponding recommended registry settings are as follows:

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Control\FileSystem\NtfsDisable8dot3NameCreation = 1

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Control\FileSystem\NtfsAllowExtendedCharacterIn8dot3Name = 0

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Control\SessionManager\MemoryManagement\ LargeSystemCache = 1

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Control\SessionManager\MemoryManagement\ DisablePagingExecutive=1

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\ Control\SessionManager\MemoryManagement\

  • IoPageLockLimit = N, where N is chosen as follows:

    • if RAM <= 32MB then

    • IoPageLockLimit = 512

    • if RAM > 32MB then

    • IoPageLockLimit = 4K

    • if RAM > 64MB then

    • IoPageLockLimit = 8K

    • if RAM > 128MB then

    • IoPageLockLimit = 16K

    • if RAM > 160MB then

    • IoPageLockLimit = 32K

    • if RAM > 256MB then

    • IoPageLockLimit = 64K

Note that I have included on the books DVD and download website a free Windows to easily set all these parameters on both local and remote database server as shown below in Figure 3.

Figure 3:  Windows Registry Settings

Obviously, installing anti-virus and anti-spyware software on the virtual server host is totally unnecessary because all it is going to do is run the operating system and hypervisor so that it can run clients. There will generally be very little direct use of this machine, except perhaps by the administrator during routine maintenance operations such as OS patches and backups.

Finally, I want to recommend that readers consider the DXtreme for Windows product line from InovaWave ( DXtreme augments the host operating system with a predictive optimization engine that can yield truly amazing results and the Lite version for laptops/notebooks is under $200. They claim many benefits, including:

  • Increased number of virtual machines per server

  • Increased performance of virtual machines and applications

  • 5X improvements for streaming reads

  • 7X improvements for streaming writes

  • 25X improvements for random reads/writes

Their web page explains their various product offerings quite nicely via the table copied on the following page (Table 2). Basically, they offer products for machines ranging from laptops/notebooks to very large servers. And in all cases, their product simply makes the streamlined host operating system better at hosting virtual clients, especially those with lots of I/O such as databases. Chapter 8 of this book will include some performance comparisons done using this amazing product.

Quick Reference

Below is a summary of the recommended host optimizations:


  • Disable Hyper-Threading

  • Enable Virtualization Support


  • Kernel

    • 64-bit

    • SMP Support

    • Compile and link a Monolithic kernel

    • Possibly recompile/re-link C-runtime library

  • Memory

    • Huge Pages

  • I/O      

    • /etc/fstab add ,noatime

  • Remove non-essential software components

  • Disable non-essential background processes/services


  • Version

  • 64-bit

  • Windows 2003 Enterprise R2

  • Registry (use my freeware program to update)

  • Disable last access update

  • Disable 8 dot 3 name creation

    • Enable large size file system cache

    • Disable paging of kernel code

    • IO Page Lock Limit >= 16K

    • Remove non-essential software components

    • Disable non-essential background processes/services

    • No anti-virus or anti-spyware programs installed

    • Buy DXtreme virtualized server IO enhancement software


In this chapter, we looked at how to best configure our centralized host and its subsystems in order to maximize database performance. The goal was to hit the center bulls-eye in order to score the most points, which meant to optimize the host first and foremost. All of these techniques should be considered as best practices and liberally implemented across all your host machines for the benefit of all their guest operating systems. The cost to implement each of these concepts is relatively small, but both their individual and cumulative performance impacts are well worth the trouble.

This is an excerpt from
Oracle on VMWare: Expert tips for database virtualization by Rampant TechPress.


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