Re: database revovery issue(my system is down)

On 28 Oct 2003 20:28:36 -0800, hopehope_123_at_yahoo.com (utkanbir) wrote:

>Hi Gurus,
>
>
>I am using oracle 9i rac on linux itanium , with emc disk + raid 5. We
>are building a datawarehouse system .Today ,
>we got error in one of the disks , unfortunately that disk contains
>system.dbf.
>Than the disk is replaced , when we try to start the database , we got
>corrupted blocks . DB verify also reported corrupted blocks in
>system.dbf and user.dbf. So we decided to recover database BUT:
>
>our data backups does not contain all the tablespaces , it contains
>system,undo,user ... but not our data tablespaces. (This is beacuse of
>the itanium machine .Our data backup software has no version for
>itanium , the only way to backup data is first store it in disk than
>tape. We dont have enough disk space to store all the data archive.)
>Is it possible to recover this database by using this backup? If i
>recover system,user,undo tablespace , will i use the other tablespaces
>again? I know that other tablespaces have no corrupted blocks.
>
>'recover database using backup controlfile'
>
>We tried the command , it asks some redo log file numbers to recover ,
>than we
>resetted the redo logs. But we still get data block corruption
>messages and database cant be opened.
>
>If i restore system.dbf , undo and user , can i use other tablespaces?
>May be we made a great mıstake of resetting logs.Instead of
>resetting logs , we must recover system.dbf from backup ??
>
>**********
>By the way , i can open database as read only , and get my data. But
>some queries against dictionary gets corruption messsages , suc as
>tab$, dba_tables,etc..
>***********************
>
>
>So , within this current situation , if i do full restore and returns
>the tablespaces that are inside archive but not the others , what will
>be the status of other tablespaces? I mean if dbserver stores the
>information about tablespaces inside system or control files , can
>recovering them solve my problem since those tablespaces data are
>valid? Or will the status of other tablespace be offline? Than may be
>a patch can be applied?(if exists) Is there any number inside
>tablspaces (may be in headers) which describes the redo log number
>which is necessary for that tablespace? What is the relation between
>redo log file numbers and tablespaces?
>
>Any help will be appreciated,
>Kind Regards,
>hope (although it remains less ...)

As you might have guessed, inevitably you will only be capable to recover the database, after you have dropped the tablespaces you have no backup for. And, sorry to say so: your 'resetlogs' command didn't make things better.

Oracle keeps a System Change Number in the controlfiles and all datafile headers and all redolog file header. If the SCN of a datafile is older than the SCN of the controlfile, Oracle will force you to recover. If you don't have any backup at all of your tablespaces, your only hope is you are running in archivelog mode, and have a backup of your archive logs. Otherwise you are definitely toast.

--
Sybrand Bakker, Senior Oracle DBA