Re: Space lost?

[Eriberto <eriberto@eriberto.pro.br>]

Hello David. Thanks for your reply!

David Masover escreveu:

> In other words, those 604 KB are things like the magic number, so
>
>utilities like "file" can guess what FS it is, or what type of file if
>it's an image, and mostly things like the journal and the amount of
>space it takes to represent one empty folder.
>  
>
Ok. I am intrigued with a fact: the ext3 uses 14 MB (14.935 KB) when 
formatting the same partition. Is this a magic number too? It is very 
large! As the Reiser4, ext3 uses 5% of space to administration by super 
user. However this 5% are inserted in the patition use (the 14 MB as 604 
KB are out of patition). For that I know, the journal is in the 
partition too. When I format a partition, immediately after the df 
command shows a amount used. This is the journal. Or not?

>And btw, if you put exactly 100KB on your disk, split into 1KB files,
>you're probably going to notice your disk usage going up by more than
>exactly 100KB.  How much it goes up by is going to be roughly equivalent
>to how much space it takes to store the name of each 1KB file.
>
>Here's another interesting experiment:  Take a directory tree of lots of
>small files.  Gentoo's /usr/portage is a good example.  Copy it to ext3,
>XFS, reiserfs, and Reiser4, then run "du -s" on each copy.  I can almost
>guarentee that Reiser4's is going to be significantly smaller, enough to
>show up on even "du -sh".  Smaller by tens of megabytes, at least.
>  
>
I heard to say that Reiser adapt the size of the block to the size of 
each file. Is true this?

>So you really shouldn't complain about your lost 604 KB.
>
>  
>
I need to understand how this works to be able to explain to my pupils.

Thanks in advance!