Jason White wrote:
Rohan McLeod <rhn@jeack.com.au> wrote:
So to your knowledge: 1/ no FS does this 'contiguous allocation' ?; I'm not aware of any. 2/ the reason being that ' the cost of re-arranging the files contiguously ', is greater than 'the cost defragmentation' ?; I'm confident it would be done if there were a performance benefit.
Jason thanks for replying; No doubt you are right; but it is far from intuitive. If I imagine a disk space containing say n groups of contiguous files, comprising say m bytes in total; separated by n-1 free-spaces comprising f bytes in total; then making those groups contiguous, would seem to simply involve, moving m bytes of n contiguous files, toward the front of the disk, so the free-space is moved to the other end of the disk. Whereas in a file system which allows fragmentation; if those n-1 free-spaces were occupied by a fragmented file say; then to get to a contiguous, set of contiguous files would seem to involve 1/ moving the f bytes of the fragmented file to the end of the disk to defragment it 2/ moving the m bytes of the contiguous files to the front of the disk 3/ moving the f bytes of the defragmented file again, up to the end of the rest of the contiguous files ? ie m bytes in the first case and m + 2.f bytes in the second ! regards Rohan McLeod