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"dba_data_files" sizes disagree with Op. Sys?

From: James Damiano <>
Date: Wed, 08 Aug 2001 06:52:35 -0700
Message-ID: <>

Dear fellow DBAs,

I have an Oracle Standard 8.1.6 database on Windows/NT 4. While doing a cold backup (database shut down and services closed) in which I FTP'd the datafiles over to a Unix machine, I noticed something peculiar:

There appears to be a mismatch when it comes to the number of bytes Oracle reports to me with the "dba_data_files" view as the size of the datafiles in my database --- and the size they are known to be by the operating system. Specifically:

SQL> select substr(file_name,1,40) file_name,

  2         bytes,
  3         user_bytes

  4 from dba_data_files
  5 order by file_name;
file_name                                                        bytes
--------------------------------------                        ---------     

...\oracle\oradata\db00\indx1db00.ora 186378240 186376192
...\oracle\oradata\db00\rbs1db00.ora 179980288 179978240
...\oracle\oradata\db00\sys1db00.ora 53663744 53661696
...\oracle\oradata\db00\tmp1db00.ora 134217728 134215680
...\oracle\oradata\db00\usr1db00.ora 219064320 219062272

However, when I look at the actual number of bytes that are reported by either Windows Explorer, by FTP in doing the transfer, or by the Unix box which is the destination, I find the following:

file_name                                                         bytes
----------------------------------------                         ---------

...\oracle\oradata\db00\indx1db00.ora 186380288
...\oracle\oradata\db00\rbs1db00.ora 179982336
...\oracle\oradata\db00\sys1db00.ora 53665792
...\oracle\oradata\db00\tmp1db00.ora 134219776
...\oracle\oradata\db00\usr1db00.ora 219066368

By the way, the block size for the database is 2048 and all the "Bytes" in these listings are divisible by the block size. Notice that the "bytes" from dba_data_files is one block bigger than "user_bytes" from dba_data_files. But, (and the heart of the matter is this) --- "bytes" as reported by Windows Explorer and Unix is one block greater than that! Does anybody know why there is this mismatch - or am I missing something obvious?

Another bit of information, all the datafiles are "AUTOEXTENSIBLE".

Thanks very much,

Jim Damiano

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Author: James Damiano

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Received on Wed Aug 08 2001 - 08:52:35 CDT

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