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Sunday, December 13, 2015

ORACLE FAL_CLIENT and FAL_SERVER explained


FAL_CLIENT and FAL_SERVER are initialization parameters used to configure log gap detection and resolution at the standby database side of a physical database configuration. This functionality is provided by log apply services and is used by the physical standby database to manage the detection and resolution of archived redo logs.

FAL_CLIENT and FAL_SERVER only need to be defined in the initialization parameter file for the standby database(s). It is possible; however, to define these two parameters in the initialization parameter for the primary database server to ease the amount of work that would need to be performed if the primary database were required to transition its role.


Sample setup:

In Primary site:

FAL_SERVER=STANDBY
FAL_CLIENT=PRIMARY

In Standby site:

FAL_SERVER=PRIMARY
FAL_CLIENT=STANDBY

UNIX Permissions - table

Unix/Linux Permissions:

Here is the list of values and what they stand for in unix folder/directory permissions.Basically it is a simple you can count the value by using octa decimal binary numbers 421 :


See below image 



Value 0 directory listing is 000 = 0+0+0 
Value 1 directory listing is 001 = 0+0+1
Value 2 directory listing is 020 = 0+0+0  

This is where they gain their permission from :

so simple chmod 1 will give execute only permision on file/folder
so simple chmod 2 will give write only permision on file/folder
so simple chmod 3 will write & execute permision on file/folder

chmod 775 test.txt >> this mean 7 for 

UNIX Permissions

ValuePermissionDirectory Listing
0No read, no write, no execute---
1No read, no write, execute--x
2No read, write, no execute-w-
3No read, write, execute-wx
4Read, no write, no executer--
5Read, no write, executer-x
6Read, write, no executerw-
7Read, write, executerwx

Friday, December 11, 2015

DATABASE NAME MAX SIZE in ORACLE



This is for 11gR2:
The length of DB_NAME is limited to 8 characters;
DB_UNIQUE_NAME is limited to 30 characters. DB_UNIQUE_NAME  can contain alphanumeric, underscore (_), dollar ($), and pound (#) characters, but must begin with an alphabetic character.
INSTANCE_NAME defaults to ORACLE_SID. Oracle document does not specify the limit for INSTANCE_NAME length. However if you describe V$INSTANCE view you can see that column INSTANCE_NAME  has VARCHAR2(16), indicating the  limit of 16 characters.
Because INSTANCE_NAME defaults to ORACLE_SID you need to be careful when deciding SID before creating a database. Oracle does not clearly define the limit for SID (system identifier). Following are what I found from two 11gR2 documents about ORACLE_SID.