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I have the following situation:

  1. Backups of DB1(located on srv1 server) database are taken everyday at 1:00 AM.

  2. I took backed up files(datafile,archivelog,controlfile,spfile) of 24/10/2011 and restored them on the server srv2.

  3. During recovering Oracle required log file:

    RMAN-06054: media recovery requesting unknown archived log for thread 1 with sequence 228 and starting SCN of 26651733

  4. I searched that logfile on the server srv1 and copied it to the server srv2. Registered it with the database and run recover database command again. Still the same error, but with other sequence number and SCN.

    RMAN-06054: media recovery requesting unknown archived log for thread 1 with sequence 229 and starting SCN of 26654944

These archivelogs are generated after 24/10/2011 so backup of this date should not know about newer archivelogs. I can set recovery until that sequence but I just wonder to know where is that SCN stored? Why does my Oracle requires newer archivelogs?

Server srv1 and srv2 are not contacting with each other.

Thank you a lot.

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1 Answer 1

up vote 3 down vote accepted

Each redo log file (and archived redo log file) contains starting SCN and ending SCN. In case it is a last redo, the ending SCN is 0xffffffffffff.

nap01:~/oradata/jt10g$ strings redo01.log|head -3
z{|}
JT10G
Thread 0001, Seq# 0000000004, SCN 0x0000000b05b5-0x0000000bd34f

nap01:~/oradata/jt10g$ strings redo02.log|head -3
z{|}
JT10G
Thread 0001, Seq# 0000000005, SCN 0x0000000bd34f-0x0000000bf612

nap01:~/oradata/jt10g$ strings redo03.log|head -3
z{|}
JT10G
Thread 0001, Seq# 0000000006, SCN 0x0000000bf612-0xffffffffffff

Until database sees 0xffffffffffff it keeps asking for further logs. But it is not a problem, you can specify UNTIL SCN or UNTIL CANCEL for your recovery (this means you don't want a complete recovery, in other words you want to lose some recent data).

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2  
Nice answer and illustration. –  Niall Litchfield Nov 25 '11 at 8:44
    
The best answer I have ever seen about this subject. Thanks a lot. –  kupa Oct 30 '13 at 10:18
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