11 Replies Latest reply: Aug 30, 2013 4:38 AM by Oracle_24 RSS

    How to restore ASM backup ?

    Oracle_24

      Hi Experts,

       

      I am working as Oracle DBA but i am new to ASM.

       

      I have backup of Oracle 11g ASM disks which was taken using 'dd' command. (Taken by someone)

       

      Now is it possible to restore this backup on new setup and then covert in to normal oracle database ?

       

      If yes will you please guide me or some link so i can refer.

       

      Thanks

        • 1. Re: How to restore ASM backup ?
          Pavan Kumar

          Backup taken using dd command is not reliable as far as I know.

          Better I would say to have go through Oracle Documentation and understand ASM and then perform the things.

          Don't be in rush.

           

          - Pavan Kumar N

          • 2. Re: How to restore ASM backup ?
            Levi Pereira

            Oracle_24 wrote:

             

            Hi Experts,

             

            I am working as Oracle DBA but i am new to ASM.

             

            I have backup of Oracle 11g ASM disks which was taken using 'dd' command. (Taken by someone)

             

            Now is it possible to restore this backup on new setup and then covert in to normal oracle database ?

             

            If yes will you please guide me or some link so i can refer.

             

            Thanks

            Hi,

            What is the purpose of backup raw of ASM Disk?

            None. Except if the purpose is a Lun copy or specific purpose.


            ASM filesystem is provided by a ASM DISKGROUP which contains a set of ASM Disk.


            Comparing: Linux Volume Group is like a ASM Diskgroup  and  Physical Disk is like a ASM DISK

            What is the purpose of backup a Physical Disks of Linux VG with dd command? How to restore it?  Is the same concept with ASM.


            Backup of ASM Disk has no consistent guaranteed unless the ASM Disk is not in use.


            To backup Oracle Database over ASM, you should use RMAN as in any other filesystem.

            Backing Up the Database


            To try restore this dd backup you must have same configuration as target host.

            Probably your dd backup are inconsistent, unless the ASM Disks is not in use at moment of copy.


            Post here the script used to make this backup.



            • 3. Re: How to restore ASM backup ?
              Oracle_24

              Hi

               

              Thank you very much for your time,

               

              Actually There was no specific purpose.

              But current purpose is if we can restore this on new machine then we are going to test our new application with actual data.

               

              Yes currently i have backup only but let me try to get that DD command.

               

              Will you please tell me what else i should have to restore the DB ?

               

              Really thanks as it is really helpful.

              • 4. Re: How to restore ASM backup ?
                Dude!

                ASM provides it's own methods of data striping, redundancy and data management. You can probably use the dd or dump command to restore individual disks in an offline ASM system, but you cannot use it to restore a live ASM system without breaking its data integrity. In order to protect from ASM disk failure you will need to use external RAID or use ASM data mirroring.

                 

                 

                I'm afraid there is no other alternative than to learn how to manage and understand ASM and RMAN, or to use database backup mode and file system copy for the purpose of database backup.

                • 5. Re: How to restore ASM backup ?
                  Levi Pereira

                  >>Will you please tell me what else i should have to restore the DB ?

                  Options...

                  1º option:

                  you really need the guy which made this backup.


                  2º option:

                  You need someone which understand how this backup was made to try restore it.


                  3º option:

                  Try by yourself using white paper of Storage Cloning and ASM such aBCV / Split Mirror / SRDF / HDS / Flash Copy


                  • 6. Re: How to restore ASM backup ?
                    Oracle_24

                    Oracle was completely shutdown before dd was used.

                    • 7. Re: How to restore ASM backup ?
                      Oracle_24

                      Okay

                      First i have to go with 2nd option.

                      • 8. Re: How to restore ASM backup ?
                        Dude!

                        Sorry, that's not the point. The problem is that your device dump will not match the content of any ASM disk that was in use after the dumpfile was created. ASM may have removed, relocated or otherwise modified data on a device, which is not recorded in the device dumpfile or device backup. It is similar to an Oracle database, for instance, you can restore a datafile, but you cannot use it until you apply redologs to achieve system integrity.

                        • 9. Re: How to restore ASM backup ?
                          Oracle_24

                          Okay

                           

                          Thanks for your time & help Dude,

                          I have start reading/understanding ASM

                           

                          But still last point wanted to discuss

                           

                          1) Oracle database was completely shutdown

                          2) Disk Backup was taken using 'dd' command

                           

                          Now if i will do (May be completely wrong)

                           

                          1) Create new ASM instance with only single parameter instance_type

                          2) Copy ASM file from backup disk/directory over this new machine

                          3) Start database and create diskgroup  with copied asm files

                          4) Specifiy diskgroup in init file

                          4) Shutdown - Startup

                           

                          Is there any chance?

                          • 10. Re: How to restore ASM backup ?
                            Dude!

                            To be honest, I have not really tried that and actually see no real benefit in doing it. But I assume that if you shutdown the ASM instance and hence also all databases connected to it, then you could perform a backup of all the disk devices in an ASM instance and rebuild the complete enchilada from scratch. I think however this method is very inefficient for routine backup and the practical use to restore information is very limited.

                            • 11. Re: How to restore ASM backup ?
                              Oracle_24

                              Thanks for your time Dude

                               

                              I will inform you when i will try this as will do for just testing purpose.