Car Solutions QPI-G7-MAIN-V2.0 Installationsanleitung PDF herunterladen (Seite 17)

tablespace extent sizes. The table extent sizes didn’t make nearly as much difference whether it was 1MB or larger,

also using increments of power of 2 steps (1, 4, 16, or 64). The performance results were fairly similar.

Be aware that if using large table extents on tables with a large number of partitions the minimum table size can be

very large, so it is best to use large extents for fact tables and very large dimension tables. For example if using

64MB extents for a table with 2500 range partitions would yield storage consumption at a minimum of 160GB

(=2500*64MB) and if using composite partitions it could be drastically more consumption of storage space.

Figure 8. Results of Oracle table scan throughput using different ASM allocation unit sizes

Linux configuration details

When installing and configuring Red Hat Linux on the DL980 server please refer to the Red Hat Enterprise Linux 5

Installation Guide and the 5.7 Release Notes.

Enable NUMA mode

The 8-socket DL980 G7 with HP PREMA architecture performs very much like a traditional SMP system. The non-

uniform memory access (NUMA) nature of the Xeon architecture is less pronounced than on many other enterprise

platforms. Some minimal investigation of the Oracle database NUMA features was done as part of the work

described in this white paper. We saw some improvement on small queries when enabling those features with

“_enable_NUMA_support=TRUE”. That setting did not have any discernable impact for larger, BI-type queries. Test

your application workload to determine if NUMA will provide additional performance.

Use HUGE pages for SGA

The so-called “Huge page” feature of Linux is strongly recommended for all DL980 installations of Oracle. Please

reference “HugePages on Oracle Linux 64-bit [ID 361468.1]” located on the Oracle support website –

http://support.oracle.com.

Huge pages will save memory. For each user connecting to Oracle, the operating system creates a new copy of the

SGA page table. With regular 4K pages, the OS page tables quickly grow bigger than the SGA itself. For example,

an 800GB SGA with 1024 users would need 1.6TB of page tables. In practice the physical memory is limited, so the

SGA would have to be scaled back to 266GB because the page tables would need 534 GB of memory.

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Car Solutions QPI-G7-MAIN-V2.0 Installationsanleitung Seite 17