Disk configuration

[KC]

Dear List,   Someone told me when a disk receive a write request, it write to the nearest free space on disk where the disk read/write head is currently positioning, is this information correct?? If this is true, is this a bad thing for database application?? That mean we can't really control where the file go, for performance purpose we may want to put certain files on the outer tracks of a disk, if the write location is depending on where the read/write head is, how can we avoid that, can we create subdisks from the outer track of a disk and create a logical volume from it??   KC