Disk IO rate on Oracle Database Sever

iostat -d -m

iostat -d /dev/sdc -m -x 2

   where

         /dev/sdc is the name of the disk  ( refer my earlier post on how to map ASM device to physical disks)

         await is disk response time

         svctm is time to process i/o request by disk

Hope this help! Rupam

How to find mapping of ASM disks to Physical Devices?

1.Login as oracle and list ASM diskgroups

$ oracleasm listdisks

DATA1

2. Query Disk

$ oracleasm querydisk -d  DATA1

Disk "DATA1" is a valid ASM disk on device [8, 33]

3. oracleasm querydisk  DATA1  you will get in addition the major - minor numbers, that can be used to match the physical device,

# ls -l /dev |grep 8|grep 33

brw-r----- 1 root disk     8,  33 Aug  2 16:10 sdc1

Hope this help! Rupam

FlashBack Restore Point in oracle

1.  Requirements for Guaranteed Restore Points

The COMPATIBLE initialization parameter must be set to 10.2 or greater.

The database must be running in ARCHIVELOG mode.

A flash recovery area must be configured Guaranteed restore points use a mechanism similar to flashback logging. Oracle must store the required logs in the flash recovery area.

Oracle 10.2

If flashback database is not enabled, then the database must be mounted, not open, when creating the first guaranteed restore point

SQL> ALTER DATABASE FLASHBACK ON;

Oracle 11.x

There is no need to mount the database. Flashback can be tunred on at open state.

SQL> ALTER DATABASE FLASHBACK ON;

2. Creating Restore points [CREATE RESTORE POINT]

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# Create Normal restore points SQL> CREATE RESTORE POINT before_upgrade; #Create guaranteed restore points SQL> CREATE RESTORE POINT before_upgrade GUARANTEE FLASHBACK DATABASE;

3. Listing restore points [V$RESTORE_POINT]

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# To see a list of the currently defined restore points SQL>SELECT NAME, SCN, TIME, DATABASE_INCARNATION#,     GUARANTEE_FLASHBACK_DATABASE,STORAGE_SIZE FROM V$RESTORE_POINT; #To view only the guaranteed restore points: SQL>SELECT NAME, SCN, TIME, DATABASE_INCARNATION#,     GUARANTEE_FLASHBACK_DATABASE, STORAGE_SIZE FROM V$RESTORE_POINT     WHERE GUARANTEE_FLASHBACK_DATABASE='YES';

For normal restore points, STORAGE_SIZE is zero. For guaranteed restore points, STORAGE_SIZE indicates the amount of disk space in the flash recovery area used to retain logs required to guarantee FLASHBACK DATABASE to that restore point.

4. Dropping restore points [DROP RESTORE POINT]

1 2	#Same statement is used to drop both normal and guaranteed restore points. SQL> DROP RESTORE POINT before_app_upgrade;

5. Turn of Flashback

SQL> ALTER DATABASE FLASHBACK OFF;

Hope this helps! Regards Rupam