http://www.itpub.net/showthread.php?s=&threadid=314067

Even if not for the purpose of transferring datafiles across OSes, it would be interesting to see what the first block of a datafile (or a controlfile and a redo logfile) at OS level contains. A datafile and controlfile has that first block of db_block_size and a logfile has a block of 512 (on most OSes) not accounted for by Oracle; that is, v$datafile.bytes, cffsz*cfbsz from x$kcccf, v$log.bytes, respectively, all fall short of one block. It probably contains information at OSD layer (for different layers, see http://www.oreilly.com/catalog/orinternals/chapter/ch01.html). Whenever you get an skg... error, your knowledge of this OS-level first block may prove to be useful.

It looks like the Oracle-filesize (not OS filesize) on Windows is recorded at a different location than that on Linux. I'm using 10.1.0.2.0 running on XP with db_block_size 8192. My dd.exe is from http://unxutils.sourceforge.net.

C:\Oracle\oradata\orcl10g>od -h EXAMPLE01.DBF -N 8192
0000000 a200 0000 0000 ffc0 0000 0000 0000 0000
0000020 52bb 0000 2000 0000 297d 0000 7c7d 7a7b
0000040 0000 0000 0000 0000 0000 0000 0000 0000
*
0020000

C:\Oracle\oradata\orcl10g>od -h sysaux01.DBF -N 8192
0000000 a200 0000 0000 ffc0 0000 0000 0000 0000
0000020 055e 0000 2000 0000 7e98 0000 7c7d 7a7b
0000040 0000 0000 0000 0000 0000 0000 0000 0000
*
0020000

Dir shows:

01/18/2005  11:15 AM        87,015,424 EXAMPLE01.DBF
01/19/2005  04:09 PM       265,494,528 SYSAUX01.DBF

For my EXAMPLE01.DBF, 87,015,424 is 10622 blocks. 10611 is 297D, which are the 25th and 26th bytes counting from the beginning sequentially (actually I should say 25th-28th bytes because the 0000 following 297d must also represent the filesize, the high digit part). Your example shows that on Linux the Oracle filesize is at 9th-12th bytes.

For my SYSAUX01.DBF, 265,494,528 is 32409 blocks. 32408 is 7E98, shown at 25th-26th bytes.

I also notice that all my datafiles have exactly the same first 16 bytes, the same 29th-32nd bytes (7c7d 7a7b), and all NUL's after that.

Yong Huang