Overwrite Mechanism

Andreas Dilger adilger at sun.com
Wed Feb 24 21:37:26 UTC 2010

On 2010-02-24, at 01:49, Schrittesser, Florian wrote:
> i wanted to ask you all about the exact overwrite mechanism used in  
> ext3; is the information in the datablocks overwritten or written to  
> a new location and the information in the referring inode is  
> changed? Is it depending on the application used (and the functions  
> it calls) or independent from that?
> Please don't hesitate to go into further details and thanks for your  
> help!

It depends on what your application is doing.  If it is opening the  
file with open(O_TRUNC) then writing it, the new data is written to  
wherever it is allocated.  If O_TRUNC is not used, then the data is  
written into the same blocks as were previously allocated to the file.

Cheers, Andreas
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

More information about the Ext3-users mailing list