Oh, sh.t ;)
Well, no big clue to see that, if the real size is zero!
I hope, i'll think a little deeper next time i am asking, thanks again for your
time spent to answer.
Kind regards, Florian
> -----Ursprüngliche Nachricht-----
> Von: John Haxby [mailto:john.haxby@xxxxxxxxxx]
> Gesendet: Dienstag, 16. Dezember 2008 16:14
> An: Rustedt, Florian
> Cc: xen-users@xxxxxxxxxxxxxxxxxxx
> Betreff: Re: AW: [Xen-users] Understanding sparse-files
>
> Rustedt, Florian wrote:
> > Thank you!
> >
> > That was exactly what i needed ;)
> >
> >
>
> My pleasure.
>
> > Does the choosen blocksize has impact on the formatting, so
> do i need to take smaller blocksizes if i want to use the
> space with the filesystem i am choosing more efficiently?
> > Or is it just for calculation, so formatting a "dd bs=512K
> seek=2048" results exactly in the same filesystemlayout after
> formatting as a "dd bs=1M seek=1024" would do?
> > So in both cases, i can use a "mkfs.ext2 -b 512 huge" and
> the resulting file mounts in both cases equally with a 256
> Byte blocksize?
> >
>
> Files don't have block sizes :-) dd just multiples the
> block size and
> seek to find the starting offset. In fact, as the count is
> zero (write nothing at all to the file), dd bs=1M seek=20480
> count=0 turns into this:
>
> open("/dev/zero", O_RDONLY) = 3
> dup2(3, 0) = 0
> close(3) = 0
> lseek(0, 0, SEEK_CUR) = 0
> open("huge", O_RDWR|O_CREAT, 0666) = 3
> dup2(3, 1) = 1
> close(3) = 0
> ftruncate(1, 21474836480) = 0
>
> The important call is the last one.
>
> jch
>
>
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