In article <slrncn75f3.2ec.stephane.chazelas@spam.is.invalid>,
Stephane CHAZELAS <this.address@is.invalid> wrote:

>  On Solaris-2.3   ...  Solaris-2.5.1  there  is  a  special
>  ioctl() called _FIOAI  that  allows  root  to  get  the
>  allocation info more efficiently.  Other operating sys- tems
>  lack support to get the real allocation  list  and force  star
>  to  scan the files to look for blocks that only contain null
>  characters.  This may star to  assume more  holes to be present
>  than the number that the file really contains.

Is there a problem with this assumption?  The usual objective is to
optimize disk space.  If the new file uses even less space than the
original file, because the original had some real disk blocks that were
all-zero, isn't that even *better* than reproducing the holes accurately?

The main benefit of the ioctl() is that it allows the holes to be
reproduced more efficiently, since star doesn't have to do any scanning.

--
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

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