Disk Space Preallocation

therube · Post by **therube** » 24 Apr 2007, 19:38

Note: Salamander (version 2.5) will not fragment your destination drive because files are prealloacted at the beginning of each operation (Copy/Move/Unpack/...).
http://forum.altap.cz/viewtopic.php?p=8658#8658

How does that work when an overwrite condition exists?
Especially with limited free disk space available?
Is the file space of the file to be overwritten released before the copy/move takes place?

Post by **Jan Rysavy** » 24 Apr 2007, 20:01

Whole target size is allocated at the beginning of operation instead of allocating new (small) fragments. For more information please look at available NTFS documentation (I don't know details).

> Is the file space of the file to be overwritten released before the copy/move takes place?

Try it

(hint: Yes, it is.)

therube · Post by **therube** » 24 Apr 2007, 22:33

Another question.

Since you are preallocating, does that mean that the space used is contiguous?

(I gather by your reply above, that you're simply performing a system call, & NTFS handles the actual allocation, & it uses its' best means to allocate in contiguous blocks?)

Post by **Jan Rysavy** » 24 Apr 2007, 22:42

The NTFS does preallocation (we only tell the size). If there is not contiguous space available, the destination file will be fragmented.