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Sunday, 5 January 2014

DATABASE


DATABASE

A. What are ora – 01555 errors?
    This is also called read in consistency error. This is called “snapshot too old “create some more roll back segments to avoid this error.

B. DB13: define backup schedule
    Click on date and select backup – type [offline/online] and save

C. Error codes:
    TNS 12560 – listener problems
    ORA 253, 255 – oracle struck
    ORA 01034 – no comparable error

D. What is sap scheduler?
     DB calendar (DB14)

E. While starting sap, I get an error, how to solve the problems?
     Login as <Sid>adm
     #r3trance –d
    Should returns you 0000 return codes if it is 0012, then look for trans/log file for detail error.

F. BRTOOLS
    Br tools read the parameter init<Sid>.sap

G. BRCONNECT:
     It is used to connect the database and perform the various administrative tasks
     # Brconnect –f check: to check the database and writes the logs into sap check directory
     # brconnect –f stats: it is used to run the database statistics. It identifies the tables whose statistics are out
     based and update them.
     # Brconnect –f cleanup: it is used to clean the old log files from sap trace & sap check directory
     # Brconnect –f next: next extents can be increase automatically

H. Db optimizer: all the tables & indexes will be stored known as a DB optimizer

I. Br – backup: it is used to take the take the backup of the database. These are 2 types
   Offline backup: the database is down during backup & no transaction is allowed
   Online backup: the database is up & running without effecting the user transaction
   Redo logs the generate during the back up
   Partial backup: it is taken for a specific table is during the patch
   Complete backup: take the full backup of system without catalog information
   Wholes ---> take the backup with catalog information
   Incremental: for incremental backup, first take the full backup system [Ex: 1   2   3   4, add the   5    6 then
   incremental]

J. Parameters:
    Backup_mode = all
    Backup_type = off line
    Backup_dev_type = tape (or) disk
    Backup_root_dir = e:\oracle\<Sid>\sap backup

K. Br archive: it is used to backup the offline redo log file to tape (or) disk from ora arch directory to tape
     (or) disk
     ---> when online redo logs are full then ora arch writes contents to ora arch (offline redo logs) the content
     of ora arch is reference of off line redo logs

L. Restore database – from database back up

M. Restore database – from redo log backup

N. How to sap is independent of database?
    There is a mediator is called DB client with the help of DB client. It becomes as database independent

O. What is database client?
     Database client is used to convert the open SQL statement into native SQL statement and vice versa

P. How to db client connect to oracle?
    LISTNER will provide the connectivity between the sap system and database during startup of sap system
    During the starting of sap system LISTNER will create shadow process in the ratio of 1:1 to connect to
    database

Q. LISTNER: create the shadow process which are going to connect the database table “SAPUSER” by
     using ops$ mechanism
    Ops$ mechanism contain the one table in database, that table is “SAPUSER” this table contains schema
    owner name & password. Shadow work process get the scheme owner name & pass word, disconnect
    (choose connection database) the database.
    Shadow process again connects to database by using schema owner name & password.

R. What is the ops$ mechanism:
     The user who is authorized at o.s level is automatically authenticared at Database level. That means no
     user ID & password is required to login to Database
     It is provide the 2 parameters are contained in RZ10 T_Code
     OS_authent_prefix = ops$
    Remote_OS_authent = true
    822379 support package know problems

S. SGEN is running one background program is PARAGENER8

T. 
Which performing the client copy PSAPUNDO table space will be increase
     NOTE: If there is no space in space in PSAPUNDO table space SNAPSHOT too old dump is thrown
     into ST22 then we need to lock after the “PSAPUNDO” table space

U. CATT: computer Aided Test tool