December 12, 2013

Sap Database Notes -3

Sap Database Notes 3:-


(1) Each and every tape used for Backup, i.e. BRBACKUP and BRARCHIVE needs to be initialized.
(2) During tape Initializing SAP specific label is written on label as First file (Tape.hdro) containing the tape name.
(3) BRTOOLS-> Backup-> Dbcopy-> Additional Functions-> Init of BRBACKUP tape Volume or Init of BRARCHIVE tape volumes.
The command to start the initialization is BRBACKUP or BRARCHIVE or –I/Initialize.

(Q) What are the contents of tape label after a tape is Initialized ?
(A) (i) Tape Name
    (ii) Name of the Database
    (iii) Time stamp of last backup recorded on the tape
    (iv) Number of Backups performed with the tape

Before writing data to tape if the label is Red to check the following
(i) Tape Name
(ii) Tape Locked or Expired(Expire_period)
(iii) No. of times the tape already been read(Tape_use_count)
If Expiration_period = 0 days, the Volume is not locked at all and can be over written
• If a lock occurs on a tape, it automatically expires at midnight.

(Q) What are the methods used by BRBACKUP and BRARCHIVE to check tape locks?
(A) There are 2 types of locks
    (i) Physical lock check: Physical lock check is done by checking tape label parameter Expir_period. If the number of days passed since the tape was last used is less than value of parameter Expir_period, then the tape is physically locked.
    (ii) Logical lock check: This value is derived from the time stamp written to tables SDBAH, SDBAD

(Q) What are the various tape selection processes?
(A) (i) Auto tape selection BRBACKUP and BRARCH
    (ii) Manual selection by the Operator
    (iii)By external tool

(Q) What is the option to select the tapes automatically by BRBACKUP and BRARCH?
(A) Set the parameter Volume_Backup and Volume_archive to TAPE

(Q) What is the command to check which tape will be automatically selected?
(A) BR Backup |  BRARCHIVE –Q | Query { check }

(Q) How do we switch off automatic tape Management?
(A) By setting up the parameter(Volume Backup and Volume Archive) to the value “SCRATCH”

(Q) How do I turnoff the tape management performed by SAP tools?
(A) Configure the parameter Backup_dev_type= UTIL_FILE
       UTIL_FILE_ONLINE and also configure BACKINT interface in init<SID>.sap
NOTE: BackINT Interface program is only supported for external Backup.

(Q) How do we verify Backups?
(A) Verification of backups is of 2 types
     (i) Tape Verification: The files are restored file by file and compared with original files to verify if the backup is redable.
     (ii) DB Block consistency: This checks the Database block by block using Oracle tool “DBVERIFY” to identify and restore from bad blocks.
PATH: BRTOOLSBackup & DBcopyVerification of DB Backup, Verification of Archive log Backup
The option USE_DBV(DBVERIFY=NO), only tape is verified (If yes Tape verification + DB Block Consistancy Check)

(1) During Backup to tape= ARCHIVE
(2) First Status= SAVED
During BACKUP TO Disk = DISK
NOTE: All the above status are recorded in ARCH<SID>.log

(1) Check Database alert log and trace files belonging to Bgprocess (SAP Trace/Background)
(i) Check for status of Database = Available or NOT Available
(ii) Check for Error = Media or User error
(iii) Check for corrupted files and file types = Data, Cofile, Online Redo log Files
(iv) Check if Software or Hardware Mirroring = Available or Not
(2) Safest method is to perform a complete Offline Backup before the files are copied back in restore place using BR Backup or any Backup Tools.
(3) The above step is Very Important for Point In Time Recovery or for Database rest because these stratagies always involve Data loss.
(4) Save Offline Redo Log Files in ORARCH Directory using BRArchive only.
(5) To check the reliability of Backup strategy , run regularly restoration report in SAP using DB12
(6) The above report is used to find out which backup to use for recovery as well as it displays information about last successful Backup.
(7) If the list of RedoLog files after the last Database Backup is too long, then perform a complete Database Backup.

Will update soon... Check next post...

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