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Give Details on Cache Fusion
Oracle RAC is composed of two or more instances. When a block of data is read from datafile by an instance within the cluster and another instance is in need of the same block,it is easy to get the block image from the insatnce which has the block in its SGA rather than reading from [...]
What is GRD?
GRD stands for Global Resource Directory. The GES and GCS maintains records of the statuses of each datafile and each cahed block using global resource directory.This process is referred to as cache fusion and helps in data integrity.
Mention the Oracle RAC software components
Oracle RAC is composed of two or more database instances. They are composed of Memory structures and background processes same as the single instance database.Oracle RAC instances use two processes GES(Global Enqueue Service), GCS(Global Cache Service) that enable cache fusion.Oracle RAC instances are composed of following background processes:
ACMS—Atomic Controlfile to Memory Service (ACMS)
GTX0-j—Global Transaction Process
LMON—Global [...]
What is RAC?
RAC stands for Real Application cluster. It is a clustering solution from Oracle Corporation that ensures high availability of databases by providing instance failover, media failover features.
How to find CPU usage for a session
select nvl(ss.USERNAME,’ORACLE PROC’) username,
se.SID,
VALUE cpu_usage
from v$session ss,
v$sesstat se,
v$statname sn
where se.STATISTIC# = sn.STATISTIC#
and NAME like ‘%CPU used by this session%’
and se.SID = ss.SID
order by VALUE desc
where
•Username – Name of the user
•SID – Session id
•CPU Usage – CPU centiseconds used by this session (divide by 100 to get real CPU seconds)
Difference between Dictionary managed tablespace (DMT) and Locally managed tablespace (LMT)
Locally Managed Tablespaces:
A tablespace that manages its own extents maintains a bitmap in each datafile to keep track of the free or used status of blocks in that datafile. Each bit in the bitmap corresponds to a group of blocks. When an extent is allocated or freed for reuse, Oracle changes the bitmap values to [...]
How to start enterprise manager from command line?
Enterprise manager can be started as follows:-
$cd $ORACLE_HOME/bin
$ emctl start dbconsole
TZ set to US/Mountain
Oracle Enterprise Manager 10g Database Control Release 10.1.0.2.0
Copyright (c) 1996, 2004 Oracle Corporation. All rights reserved.
http://localhost.localdomain:5500/em/console/aboutApplication
Starting Oracle Enterprise Manager 10g Database Control ……………………… started.
Various options for emctl are:- emctl start| stop| status dbconsole
Hardware device information in Linux
Basically manufacturer of the Card and Serial Number and Name or identifier of the Device.
You can get the card details [and all other hardware details] with ‘lspci -vvv’ command. But this may not show the serial number. You may have to check the card physically, to get the serial number.
How can I manually add a new instance to a cluster?
Assuming that the cluster is up and running and also assuming that you can connect successfully to one of the nodes.
Add redo groups to node2
alter database add logfile thread 2 ‘/u02/oradata/myrac2/redo04.log’ size 10m;
alter database add logfile thread 2 ‘/u02/oradata/myrac2/redo05.log’ size 10m;
alter database add logfile thread 2 ‘/u02/oradata/myrac2/redo06.log’ size 10m;
alter database enable thread 2;
Create [...]
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Command to list out all cronjobs which is not commented
UNIXSRV01# crontab -l | grep ^[^#]