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Old 07-26-2005, 11:59 PM   #1
p810ps
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block preallocation


Does anybody know how to turn block preallocation off?


To show what I mean:

[localhost ~]$ touch xxx
[localhost ~]$ stat xxx
File: `xxx'
Size: 0 Blocks: 8 IO Block: 4096 regular empty file
Device: fd00h/64768d Inode: 1097758 Links: 1
Access: (0664/-rw-rw-r--) Uid: ( 500/ blah) Gid: ( 500/ blah)
Access: 2005-07-22 20:46:58.000000000 -0400
Modify: 2005-07-22 20:46:58.000000000 -0400
Change: 2005-07-22 20:46:58.000000000 -0400

Blocks in the above says 8.
 
Old 07-27-2005, 12:49 AM   #2
trickykid
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What purpose of turning this feature off serves you? The preallocated blocks do not actually exist, they are just reserved within the allocated block bitmap.

A page that explains a little more: http://www.science.unitn.it/~fiorell...k/node101.html
 
Old 07-27-2005, 04:42 PM   #3
p810ps
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I need it because I am building an embedded system. And in my situation these blocks do exist.
The funny thing is that I have 2 FC3 systems: one is doing preallocation the other doesn't.
 
Old 07-28-2005, 03:14 AM   #4
foo_bar_foo
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my system doesn't do that either (reiserfs) kernel 2.6.8.1
it's not really fsprogs doing it of course it's the kernels implementation of the filesystem
the kernel uses struct ext2_super_block
that contains two variables
s_prealloc_blocks
s_prealloc_dir_blocks
that are set to __u8

i guess you are stuck with using another filesystem other than ext2/3 or kernel hacking
 
Old 07-28-2005, 05:25 AM   #5
p810ps
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Quote:
i guess you are stuck with using another filesystem other than ext2/3 or kernel hacking [/B]
There something else becasue I have two FC3 installed and one does it and the other doesn't.
I can also ghost the "good" image on my other machines but it's not an option (yet).

Also I used the kernel from the "good" machine on the "bad" one with no success.
ext3 modules are the same on both.

Last edited by p810ps; 07-28-2005 at 05:29 AM.
 
Old 08-13-2005, 08:43 AM   #6
p810ps
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Turned out if one installs FC3 Server one gets this preallocated blocks feature turned on.
Workstation installation has it turned off.
 
Old 08-14-2005, 12:56 AM   #7
foo_bar_foo
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wow redhat patching their kernels again with odd things.
 
  


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