Re: Restore and Recover Fuzzy datafiles

  • From: Andrey Kriushin <Andrey.Kriushin@xxxxxxxx>
  • To: mwf@xxxxxxxx
  • Date: Thu, 25 May 2006 18:04:47 +0400


Never heard of "ending block". What version it was then? Mark, could you, please, clarify?


I've been in the situation with recovery of fuzzy file(s). The customer made the backups by "split mirror" or something similar, and yes - DB was suspended before splitting the mirror. Then files from the broken half of the mirror were copied (not by RMAN) somewhere to form the "backup". However BEGIN BACKUP was not performed before the split.
Funny thing is that complete recovery was always working for them, so the problem with fuzziness never arose. Unfortunately when the time for incomplete recovery came, the customer had a big trouble. I've not noticed any problems with the "ending blocks". Did I miss something important? Server version was 9.2.0.4 if I remember correctly.
AFAIK, after opening the database all its online datafiles in read write tablespaces are in some sense fuzzy. It shows up as "stop scn: 0xffff.ffffffff" in file_hdrs dump (comes from the controlfile record for the file), and also can be seen as KCVFHOFZ flag set in kcvfh.kcvfhsta field in the file header block.
There are also additional structs in the file header block with some other meaning for "fuzzy", named as "Absolute fuzzy scn" and "Recovery fuzzy scn". Probably somebody on the list could clarify their meaning?


TIA

- Andrey

Mark W. Farnham wrote:

Before you could tell the database to "end" backup, you also had to patch the beginning and ending blocks of the file (lie to Oracle) so that Oracle did not consider the file to be "fuzzy," but I doubt you're working with a vintage of the Oracle software that old. If you are, you'll need some kind of binary block editor.




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