Car Solutions QPI-G7-MAIN-V2.0 Installationsanleitung PDF herunterladen (Seite 27)

– MEMORY_MAX_TARGET = 0 (Oracle DB 11g)

 Use the following guidelines as a starting point for sizing memory:

– Size the Oracle System Global Area (SGA) at about 70% of total memory (about 600GB for database buffer

cache with the remaining 100GB for the other SGA pools – see Oracle parameters in Appendix 2).

– Size the Oracle Process Global Area (PGA) at about 20% of total memory.

– That leaves about 10% for the Linux system management.

 A BI/DW type workload will do a lot more aggregating, sorting of data, joins, etc. than typically required for an

OLTP environment so you will need a larger PGA

 Oracle 11g introduced a new, internal mutex mechanism. While the new mutex is more efficient than previous

locks, it is essentially a spinlock and can consume lots of CPU when things go bad. It is important to eliminate

mutex contention whenever it shows up in the AWR report. For more detail see Latch, mutex and beyond.

 Multi-block read count and block size for reads of 16MB for the larger tables using 32KB blocks yielded the best

results. Small tables’ multi-block read count was 4MB using 8KB block size.

 For bulk loading of data into the Oracle 11gR2 database it is recommended to turn off redo logging for better

performance. If logging is required make sure the redo logs are sized large enough so that log switches are

greater than 3-5 minutes. There is a tradeoff between data load speeds and database logging.

Estimating number of parallel execution servers

The number of parallel execution servers associated with a single operation is known as the degree of parallelism

(DOP). Obviously, you want to use a lot of resources to reduce the response times, but if too many operations take

this approach, the system may soon be starved for resources, as you can't use more resources than you have

available. Oracle database has built in limits to prevent overload. This is where turning on Hyper-Threading can help

provide additional logical cores to assist in processing. An 80 core DL980 will have 160 logical cores. Oracle will

show cpu_count parameter as the total logical cores on the server.

 PARALLEL_MAX_SERVERS – set to 4 * number of logical cores. (4*160 = 640)

 PARALLEL_MIN_SERVERS – set to 2 * number of logical cores. (2*160 = 320)

 PARALLEL_SERVERS_TARGET – set half way between max and min servers (480)

Location of Oracle 11gR2 binaries

The Oracle database software should be installed separately from the storage used for the database instance itself.

The recommended configurations are designed with the intent that the Oracle binaries be placed on the same drives

as the OS. There is no performance benefit to separating the OS and Oracle binaries on different drives, though

some customers will chose to do so to simplify system backup and maintenance operations.

Oracle database file location

For the HP P2000 storage configuration it is recommended that the Oracle database components, such as data,

indexes, undo, temp and redo, should be managed with Oracle Automatic Storage Management (ASM) to stripe

across the storage arrays. ASM should be used in “external redundancy” mode, since the P2000 arrays themselves

will provide the RAID level protection for the databases.

Memory allocation for OS

In an Oracle 11gR2 setup it is recommended to use any extra memory available on the system for the system global

area (SGA). This can improve I/O performance. Leave 10% of the memory available for the operating system.

Storage best practices

 For backup/recovery areas just plug other servers/storage into the existing SAN fabric.

 When configuring the P2000 cache the 2 MB read ahead was best. Do NOT use “super sequential”. The problem

is that Oracle database issues multiple sequential streams for queries and the P2000 is looking for a single

sequential stream when that parameter is turned on, so the environment did not perform as well if super sequential

settings were used.

 Use the multipath.conf file to align the volume names on the storage array with their presentation on the DL980 (for

example, DATA05_A2). This will allow ready identification of underperforming storage units or failed controllers.

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