The number of disk accesses performed by B-Tree-Insert is O (h) for a B-tree of height h,since only O(1)Disk-Read and Disk-Write operations are performed between calls to B-Tree-Insert-Nonfull.
The total CPU time used is O(th) = O(t logt n). Since B-Tree-Insert-Nonfull is tail-recursive,it can pages that need to be in main memory at anytime is O(1).