Hello Obviously.
Obviously this is a standard linux (unix) behaviour. If you open a file 
its inode is associated with one process fd and it does not need to use 
the filename written in the directoty.
When you erase the file (rm, I suppose), you simply cat the name off the 
directory list, but the open fd continues to work. On file close the OS 
realizes the the use comunt of the file went to 0 and phisically delete it 
from disk, reusing the space.
Some applications use this feature for temporary files, opening them ad 
deleting immediatly. If the application stops for whatever reason no 
garbage remain around.

Regards,


--------------------------------------------------------------------------
Ferdinando Pasqualetti
G.T.Dati srl
Tel. 0557310862 - 3356172731 - Fax 055720143





Da:     obviously <bacula-fo...@backupcentral.com>
Per:    bacula-users@lists.sourceforge.net
Data:   13/05/2011 14.48
Oggetto:        [Bacula-users]  How does Bacula back-up files?



Hello,

I have a question I can't solve...

The is the situation:

I create a file with: dd if=/dev/urandom of=test.bin bs=10M count=300
This gives me a file of 3GB.
I check it's MD5 with md5sum test.bin

I clear my cache with echo 3 > /proc/sys/vm/drop_caches.

I check my chache with free -m.

I start a backup with Bacula of only 1 file, namely test.bin

Again, I flush the cache and when the back-up job is starting I remove the 
test.bin file on the server.

And Bacula doens't react at all, it keeps backing up the file like it is 
still there.

The backup finishes with no warnings, even it is removed during the 
backup.

I restore the test.bin file from tape and checks the md5 of it, and 
strangely the md5sum is the same... 

So my question, how does Bacula do this? Cause I remove the file during 
the backup and flush the cache frequently...

I hope you guys understand my q, my english is realy bad :) excuse me...

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Achieve unprecedented app performance and reliability
What every C/C++ and Fortran developer should know.
Learn how Intel has extended the reach of its next-generation tools
to help boost performance applications - inlcuding clusters.
http://p.sf.net/sfu/intel-dev2devmay
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