Oracle Memory Configuration on Windows Server Configuring Large Memory for Oracle on 32-bit and 64-bit Windows

Objectives At the end of this module the student will understand the following concepts: OS Memory Configuration 32-bit and 64-bit systems 32-bit and 64-bit systems Boot.ini file Boot.ini file /3GB, /PAE, and /NOPAE Switches /3GB, /PAE, and /NOPAE Switches Oracle Memory Configuration Awe enabled Awe enabled Performance Implications of 32-bit Oracle Advantages of 64-bit Oracle

32-bit Addressing  32-bit processors have address registers that are 32-bits wide (can address up to 4GB physical RAM)  Allows per process virtual address space of 4GB range (0 to 4,294,967,295 bytes)  Each individual process gets its own virtual address space that can be up to 4GB  This virtual address space is divided – system and user space

User and System Virtual Address Space

4GT (4GB Tuning) with /3GB /3GB = 4GB Tuning Feature – reduces system space to 1GB, allowing 3GB for user space Add to boot.ini file and reboot to take effect For systems 4GB to 16GB only

32-bit Systems with PAE (36- bit) PAE- Physical Address Extension AKA Large Memory Support Allows 36-bit memory addressing Allows the IA32 processor to address up to 64GB of physical RAM Add /PAE switch in the boot.ini file and reboot server Adds translation layer to memory access

Windows 2003 /NOPAE Special Case (32-bit) New for Windows 2003 is the /NOPAE switch Forces Windows 2003 NOT to use PAE algorithms for memory access (there is overhead involved) Should be used on systems with 4GB or less and hot-add memory devices

Boot.ini Examples (32-bit) To use /3GB or /PAE, add the switches to the boot.ini file and reboot the server Note: Using both /3GB and /PAE together conserves the most memory under 4 GB Using both /3GB and /PAE together conserves the most memory under 4 GB Using both /3GB and /PAE will limit memory addressability to 16 GB Using both /3GB and /PAE will limit memory addressability to 16 GB

32-bit Memory Size/Switch Chart MEMORY SIZE Boot.ini SWITCH < 4GB None (or /NOPAE) = 4GB /3GB (or /3GB /NOPAE) > 4GB & 4GB & <= 16GB /3GB /PAE >16GB /PAE only

Support for /3GB and /PAE – 32-bit Windows 2000 Advanced Server Windows 2000 Datacenter Server Windows 2003 Enterprise Edition Windows 2003 Datacenter Edition

32-bit Max Memory Support on x86 based computers Windows 2003 Enterprise = 32GB max Windows 2003 Datacenter = 64GB max

AWE for 32-bit Oracle Address Windowing Extension AWE – a set of APIs that allow programs to address memory locations outside of their 4GB virtual addressing range Available through 32-bit addressing With AWE programs reserve memory as non-paged (will not page out)

Implementing AWE with 32-bit Oracle Set the /PAE boot.ini flag Set the “USE_INDIRECT_BUFFERS=TRUE” parameter in the Oracle initialization file. Use the DB_BLOCK_BUFFERS parameter in the initialization file instead of the DB_CACHE parameter. The AWE_WINDOW_SIZE registry parameter sets up a “swap area” in low memory to map data buffers in high memory Default size is 1 GB. Default size is 1 GB.

Performance Implications of 32-bit Memory Management Memory split into two parts is not as efficient as memory in one segment Overhead is introduced Overhead is introduced 32-bit systems with 8 GB of RAM may not perform much better than systems with 4 GB of RAM. 32-bit systems with 8 GB of RAM may not perform much better than systems with 4 GB of RAM. May need to add 12 GB of RAM to see a noticable return for the investment. May need to add 12 GB of RAM to see a noticable return for the investment.

Performance Implications of 32-bit Memory Management Memory above 4 GB can only be used for DATA_BUFFER cache. There is little room for the Shared Pool, Large Pool, PGA, etc. There is little room for the Shared Pool, Large Pool, PGA, etc. The AWE_WINDOW_SIZE parameter takes up 1 GB of RAM The AWE_WINDOW_SIZE parameter takes up 1 GB of RAM Leaves only 1 GB of RAM for all other memory types (2 GB with /3GB) Leaves only 1 GB of RAM for all other memory types (2 GB with /3GB) The other memory types are required for supporting memory connections. The other memory types are required for supporting memory connections. As a result, Oracle on 32-bit systems is severely restricted on the number of user connections supported 100s – low thousands with Shared Servers 100s – low thousands with Shared Servers

Conserving Memory for User Connections AWE/PAE does not improve user connectivity for 32-bit Oracle User connections must share a limited pool of memory, 1-2 GB The AWE_WINDOW_SIZE registry parameter can be decreased from 1 GB to as low as 512 MB to increase user memory Tradeoff between upper memory accessibility and user memory size Tradeoff between upper memory accessibility and user memory size

Conserving Memory for User Connections Oracle initialization parameters can be used to decrease per user memory usage bitmap_merge_area_size bitmap_merge_area_size create_bitmap_area_size create_bitmap_area_size hash_area_size hash_area_size open_cursors open_cursors sort_area_size (sort_area_retained_size) sort_area_size (sort_area_retained_size) The Orastack command can be used to decrease memory use per thread Default allocation is 1 MB Default allocation is 1 MB Risky to decrease below 700KB; any change must be tested Risky to decrease below 700KB; any change must be tested Example usage: Example usage: orastack oracle.exe orastack oracle.exe orastack tnslsnr.exe orastack tnslsnr.exe orastack svrmgrl.exe orastack svrmgrl.exe orastack sqlplus.exe orastack sqlplus.exe

Windows bit Systems 64-bit versions of Windows have implemented up to 16 terabytes of virtual address space Don’t use PAE or /3GB with 64-bit 64-bit programs use 16 terabyte tuning model (8TB user / 8TB kernel) Compare to 32-bit tuning mode (2GB user / 2GB kernel) No performance penalties for large memory Unlimited user connectivity

64-bit Memory Support on Itanium based computers Windows 2003 Enterprise 64-bit = 1TB max Windows 2003 Datacenter 64-bit = 1TB max

64-bit Memory Support on EM64T and Opteron based computers Windows 2003 Standard 64-bit = 64GB Windows 2003 Enterprise 64-bit = 1TB max Windows 2003 Datacenter 64-bit = 1 TB max

Monitor Oracle Memory Oracle for Windows Performance Counters Oracle %phyreads/gets shows Buffer Cache performance Oracle %phyreads/gets shows Buffer Cache performance Should be below 10% - few physical reads as a proportion of all reads; otherwise, more memory may be required Should be below 10% - few physical reads as a proportion of all reads; otherwise, more memory may be required

Review What flag is set in the boot.ini file to use memory above 16 GB? Which two flags may be set in the boot.ini file for memory between 4 GB and 16 GB? What are the performance implications of 32-bit memory management for Oracle? What tool may be used to monitor Buffer Cache efficiency?

Summary The following topics were discussed in this training module: OS Memory Configuration 32-bit and 64-bit systems 32-bit and 64-bit systems Boot.ini file Boot.ini file /3GB, /PAE, and /NOPAE Switches /3GB, /PAE, and /NOPAE Switches Oracle Memory Configuration with AWE Performance Implications of 32-bit Oracle Advantages of 64-bit Oracle