chap lists and arrays revisited buddies buddies buddies ( (bfigure example of the buddy system (ablocks of size (bblocks of size discussed in this section the advantage of zones is that some portions of memory can be managed more efficiently the disadvantage is that one zone might fill up while other zones have excess memory if the zone sizes are chosen poorly another approach to memory management is to impose standard size on all memory requests we have seen an example of this concept already in disk file managementwhere all files are allocated in multiples of the cluster size this approach leads to internal fragmentationbut managing files composed of clusters is easier than managing arbitrarily sized files the cluster scheme also allows us to relax the restriction that the memory request be serviced by contiguous block of memory most disk file managers and operating system main memory managers work on cluster or page system block management is usually done with buffer pool to allocate available blocks in main memory efficiently failure policies and garbage collection at some point during processinga memory manager could encounter request for memory that it cannot satisfy in some situationsthere might be nothing that can be donethere simply might not be enough free memory to service the requestand the application may require that the request be serviced immediately in this casethe memory manager has no option but to return an errorwhich could in turn lead to failure of the application program howeverin many cases there are alternatives to simply returning an error the possible options are referred to collectively as failure policies in some casesthere might be sufficient free memory to satisfy the requestbut it is scattered among small blocks this can happen when using sequential