Oracle Cache fusion, private inter connects and practical performance management considerations in Oracle RAC

Originally posted on Guenadi N Jilevski's Oracle BLOG:

Oracle Cache fusion, private inter connects and practical performance management considerations in Oracle RAC

In the article you will have a look at the cache fusion from the perspective of the Practical Performance Management for Oracle RAC. Cache fusion is based and heavily depends on Private Interconnect. The article will emphasize on the Interconnects impact, often overlooked and underestimated, on the RAC performance. Tuning RAC is similar to tuning of a regular single instance database and in addition takes into account the overhead of the interconnects existing in Oracle RAC (10gR1/10gR2/11gR1/11gR2). Some well known cases will be addressed in RAC to improve performance.

In this article you will review the Oracle fundamentals and infrastructure architecture and you will look at the Cache Fusion impact on the RAC performance. The outlined in the article guidelines has two objectives:

  • Maximize the utilization of the software and hardware for Private Interconnect. Make sure that you fully utilize the maximum of your…

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Execution Plans

In-memory DB

Originally posted on Oracle Scratchpad:

A recent thread on the OTN database forum supplied some code that seemed to show that In-memory DB made no difference to performance when compared with the traditional row-store mechanism and asked why not.  (It looked as if the answer was that almost all the time for the tests was spent returning the 3M row result set to the SQL*Plus client 15 rows at a time.)

The responses on the thread led to the question:  Why would the in-memory (column-store) database be faster than simply having the (row-store) data fully cached in the buffer cache ?

Maria Colgan has addressed this question in part 3 of her series on In-Memory Database (see catalogue below), but I thought I’d repeat the basic ideas with a few imaginative numbers thrown in to give a better flavour of what’s going on. So imagine you have a table sized at 100GB, with 100 columns of data…

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Brief introduction to ASM mirroring

Originally posted on The Oracle Instructor:

Automatic Storage Management (ASM) is becoming the standard for good reasons. Still, the way it mirrors remains a mystery for many customers I encounter, so I decided to cover it briefly here.

ASM Basics: What does normal redundancy mean at all?

ASM normal redundancy

It means that every stripe is mirrored once. There is a primary on one disk and a mirror on another disk. All stripes are spread across all disks. High redundancy would mean that every primary stripe has two mirrors, each on another disk. Obviously, the mirroring reduces the usable capacity: It’s one half of the raw capacity for normal redundancy and one third for high redundancy. The normal redundancy as on the picture safeguards against the loss of any one disk.

ASM Basics: Spare capacity

ASM spare capacity usage

When disks are lost, ASM tries to re-establish redundancy again. Instead of using spare disks, it uses spare capacity. If enough free space…

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Creating Local Yum in Oracle Linux 6.3

Manual installation of Oracle required Packages is always frustrating one while installing Oracle Database in a Linux Box. Oracle Linux came up with a package named oracle-validated-preinstall to manage all installation prerequisites easily. To take advantage of it, you can configure local yum using those following steps.

First of all, create a empty directory and copy all packages from CD or ISO Image.
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ORA-12528 tns listener all appropriate instances are blocking new connections


SQL> startup nomount
ORACLE instance started.

Total System Global Area  263639040 bytes
Fixed Size                  1332552 bytes
Variable Size             222300856 bytes
Database Buffers           33554432 bytes
Redo Buffers                6451200 bytes

C:\>lsnrctl status

LSNRCTL for 32-bit Windows: Version - Production 

Service "ORCL" has 2 instance(s).
  Instance "ORCL", status UNKNOWN, has 1 handler(s) for this service...
      "DEDICATED" established:0 refused:59
  Instance "ORCL", status BLOCKED, has 1 handler(s) for this service...
      "DEDICATED" established:0 refused:0 state:ready
Service "ORCL_XPT" has 1 instance(s).
  Instance "ORCL", status BLOCKED, has 1 handler(s) for this service...
      "DEDICATED" established:0 refused:0 state:ready

Want Solution Do the following : Continue reading

Windows Batch Script for Datapump Backup

Following is the content Batch Script for taking datapump backup in Windows OS.

set mydate=%date:~-7,2%%date:~-10,2%%date:~-4,4%%time:~-11,2%%time:~-8,2%%time:~-5,2%%time:~-2,2% 
expdp system/system schemas=orbhrm directory=BACKUP_DIR dumpfile=orbhrm%mydate%.dmp logfile=orbhrm%mydate%.log exclude=TABLE:\"IN \(\'RCAPPDTL\'\)\" 

A Rahim Khan


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