MyNotes

High availability and scalability: * As a dba most scraiest word or scariest area is down time we need to expertise in this particular ares. *in that down time is the test to dba capcity only we can resolve by expertise and practice comes into picture at that time we can't google how do fail over and switch over? reason of downtime:: *as planned down time for os level paramter or the server team doing migaration old into new hardware Planned Down time *Its for doing hardware or software level ex: applying patches ,Server Hardware Upgrade,Server maintenance. Unplanned downtime: * 1)computer failure - our server completely blast,before the computer failure data failures causes the downtime. Types of downtime:: *storage failure- let us take harddisk is data stored its totally gone *site failure - due to some natural disaster our production server is gone *Human error - someone deleting the data from database *corruption - one block or sector are corrupted in h...

overview of Oracle RAC SMP vs cluster single processor machine(symmetric multiprocessing): *It involves a multiprocessor computer hardware architecture where two or more identical processors are connected to a single shared main memory and are controlled by a single OS instance. *SMP is single processing machine / single processor machine basically all of our desktops, laptop because it have dedicated ram, dedicated hard disk, and processor *It acts as one single system Cluster: *it consists of multiple systems which are connected each other to solve the business problem * ex: if we search the query in google it means the single system responds to my query, actually it behind a lot of servers are connected and gives respond for users request outside of the world it seems one big system. Cluster Management software: *If we are going to use word file we need ms office software, at the same, we are going to access pdf files we need the pdf reader like the same we n...

How to resize the redo logfile /online redo logfile in Oracle 11g? Let us we discuss How to resize the redo logfile /online redo logfile in Oracle 11g? The redo logfile contains the history of changes data in database, Oracle allows you to have more than one copy of each redo log file, This important feature is called "multiplexing redo log files." The steps to be followed to resize the redo logfile Kindly click here https://ampersandacademy.com/tutorials/oracle-admin-1/resize-the-redo-logfile-online-redo-logfile

Let us we discuss how to check sga total size & free space in Oracle11g ? 1)Total Size: * The view (V$sga) display summary information about the system global area (SGA). for more details kindly click here https://ampersandacademy.com/tutorials/oracle-admin-1/check-sga-total-size-and-free-space-in-oracle11g

let us we discuss how to find the undo tablespace expired /unexpired in oracle11g SQL> SELECT tablespace_name, status, COUNT(*) AS HOW_MANY   2  FROM dba_undo_extents   3  GROUP BY tablespace_name, status; TABLESPACE_NAME                STATUS      HOW_MANY ------------------------------             -------------       -------------------- UNDOTBS1                            UNEXPIRED         13 UNDOTBS1                            EXPIRED     ...

Let we discuss how to check the tablespace creation time in Oracle 11g? *By using this query we will get the tablespace name, status and creation time   SQL> col FILE_NAME for a45 SQL> col tablespace_name for a10 SQL> col status for a15 SQL> col creation_time for a15 SQL> set lines 999 pages 100 SQL> select a.File_name,a.Tablespace_name,a.status,b.creation_time from dba_data_files a inner join V$datafile b on a.file_name=b.Name group by a.File_name, a.Tablespace_name,a.status,b.creation_time ; FILE_NAME TABLESPACE STATUS CREATION_TIME --------------------------------------------- ---------- --------------- --------------- C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSTEM.DBF SYSTEM AVAILABLE 27-AUG-17 C:\ORACLEXE\APP\ORACLE\ORADATA\XE\USERS.DBF USERS AVAILABLE 27-AUG-17 C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SYSAUX.DBF UNDOTBS1 AVAILABLE 27-AUG-17 C:\ORACLEXE\APP\ORACLE\ORADATA\XE\SAM01.DBF...

let we discuss how to find Log switches in Database with Details of oracle11g Note: V$LOG_HISTORY displays log history information from the control file. Method-1: I am going to take log switches count till before the month end (i.e current date is '27-Sep-17' using last_day function  it consider the date is '30-Sep-2017') SQL> col c1 for a10 heading "Month" SQL> col c2 for a25 heading "ArchiveDate" SQL> col c3 for 999 heading "Switches" SQL> SQL> col c1 for a10 heading "Month" SQL> col c2 for a25 heading "ArchiveDate" SQL> col c3 for 999 heading "Switches" SQL> select to_char(trunc(first_time),'Month') c1, to_char(trunc(first_time),'DAY:DD-MM-YY') c2, count(*) c3 from V$log_history where first_time > last_day(trunc (sysdate) - 30)+1 group by trunc(first_time) order by trunc(first_time); Month ArchiveDate Switches ---------- ---------------...