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RE: datafile permissions

From: Khemmanivanh, Somckit <>
Date: Tue, 5 Jul 2005 22:30:54 -0700
Message-ID: <65C0D8935651CB4D96E97CEFAC5A12B944479F@wafedixm10.corp.weyer.pri>


Not to harp on this too much but I'm really failing to see how this is such a risky task? He's going from mode 600 to 640.  

You can run this test yourself to see that there shouldn't be any issues with doing this.  

  1. create a test file rm skf touch skf chmod 600 skf ll skf
    -rw------- 0 Jul 5 22:16 skf
  2. As a control run the supplied C program I whipped up to test. All it does is open the file and write a bunch text to it

It will create a file exactly 99999999 bytes in size  

ll skf
-rw------- 99999999 Jul 5 22:17 skf

Below is the code (compile and run it)  

#include <stdio.h>
int main ()
  FILE * myf;
  int counter = 0;  

  myf = fopen ("skf","wt");
  if (myf != NULL)

     while ( counter < 99999999)
      fputs ("t", myf);


3) Delete the skf file and recreate it with mode 600 for the run with the chmod in it.
--Run the program in 1 session and in another session run the following

ll skf; chmod 640 skf; ll skf
-rw------- 6062080 Jul 5 22:18 skf
^^^--Note the mode is 600 from the first ll skf commnd

-rw-r----- 6193152 Jul 5 22:18 skf
^^^--Note the mode has changed to 640 with the chmod comand (this while the other program is still writing to the file)  

4) Now recheck the file after it's all complete. ll skf
-rw-r----- 99999999 Jul 5 22:19 skf

Does anyone see any flaws with this test???


[] On Behalf Of Sinardy Sent: Tuesday, July 05, 2005 9:31 PM
To:; Subject: Re: datafile permissions

If someone is writing to the file then you revoke the access using OS command which is it can be done with Unix I believe your manager forsee this will corrupt the datafile.  

Anyway, if I am asked to perform such harderning change, I will request for down time. For may be 1 hour, stop applications, shutdown, chmod, startup, switch log file, test, star application. not only datafile offline.    

PS: I know that 640 should be ok but chmod during online is quite a risky task.  


        Hi All,          

	Sun OS 2.9 
	oracle 9i
	In what state the datafiles should be when i want to change the
OS file permissions
	from 600 to 640 
	chmod 640 *.dbf
	I put the tablespace offline.  is that enough?, or should i make
the datafiles offline withi          

        alter database datafile 'filename' offline;          

        I had a fight with my manager. He asked me to put the datafiles offline using alter database.

        But Just i put the tablespace offline and did that. Just want to make sure what is

        the right way (precautiion to be taken) for this task ?                    

	Thanks in advance,

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-- Received on Wed Jul 06 2005 - 00:32:57 CDT

Original text of this message