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Disk Space Preallocation

Posted: 24 Apr 2007, 19:38
by therube
Disk Space Preallocation
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?

Posted: 24 Apr 2007, 20:01
by Jan Rysavy
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.)

Posted: 24 Apr 2007, 22:33
by therube
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?)

Posted: 24 Apr 2007, 22:42
by Jan Rysavy
The NTFS does preallocation (we only tell the size). If there is not contiguous space available, the destination file will be fragmented.