The size of datafile recorded in the Oracle database datafile header

Environment of this article: Oracle databae 12.1.0.2, rhel5.9 x86-64bit

[[email protected] orcl]$ pwd/u01/app/oracle/oradata/orcl[[email protected] orcl]$ ls-lrttotal 2386544drwxr-x---2 oracle oinstall 4096 Dec pdbseeddrwxr-x---2 oracle oinstall 4096 Dec pn1d Rwxr-x---2 oracle oinstall 4096 DEC pn2-rw-r-----1 Oracle oinstall 5251072 Jul 13:26 users01.dbf-rw-r -----1 Oracle Oinstall 52429312 13:26 redo03.log-rw-r-----1 Oracle oinstall 52429312 Jul 13:26 redo01.log-rw -R-----1 Oracle oinstall 74457088 20:01 temp01.dbf-rw-r-----1 Oracle oinstall 602939392 Jul 20:25 undotbs01.d BF-RW-R-----1 Oracle oinstall 870326272 20:25 system01.dbf-rw-r-----1 Oracle oinstall 765468672 Jul 20:25 Sysa UX01.DBF-RW-R-----1 Oracle oinstall 52429312 Jul 20:26 redo02.log-rw-r-----1 Oracle oinstall 17973248 Jul 31 20:26 Control01.ctl[[email protected] orcl]$ dd if=/u01/app/oracle/oradata/orcl/system01.dbf bs=512 count=1 | Od-x1+0 Records in1+0 records out512 bytes (+ B) cOpied, 0.027559 seconds, 18.6 kb/s0000000 a200 0000 0000 ffc0 0000 0000 0000 00000000020 6567 0000 a 0000 9f00 0001 7C7 d 7a7b0000040 81a0 0000 0000 0000 0000 0000 0000 00000000060 0000 0000 0000 0000 0000 0000 0000 0000*0001000[[email p Rotected] orcl]$ dd if=/u01/app/oracle/oradata/orcl/system01.dbf bs=512 count=1 |           Od-i1+0 Records in1+0 records out512 bytes (+ B) copied, 2.9e-05 seconds, 17.7 mb/s0000000 41472-4194304           0 00000020 25959 8192 106240 20549131490000040 33184 0 0 00000060 0 0 0 0*0001000[[email protected] orcl]$ [[email protecte D] orcl]$ [[email protected] orcl]$ ls-lrt8192*106240=870318080 and LS- The LRT results show that the size of SYSTEM01.DBF is: 870326272870326272-870318080=8192, and one of the many is the OS header in DataFile, see article: How to Detect and Fix a Corruption in the datafile OS header/block zero-ora-27047 DBV-107 ora-1157/ora-27048 (document ID 360032.1)

8192 manual calculation process;
2000 0000 After flipping: 00002000, converted to decimal, is 8192

106240 Manual calculation process:
9F00 0001 flipped: 00019f00, converted to decimal, is 106240
Reference article:
How to GET datafile SIZE THROUGH DD (document ID 274445.1)
Note: This article can only provide the idea of calculation, in fact, the number of DB block inside the conversion process is wrong.

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

The size of datafile recorded in the Oracle database datafile header