@Misc{colarelli:allocate, author = {Dennis Colarelli and Gene Schumacher}, title = {New Strategy for File Allocation on Multi-device Systems}, year = {1993}, howpublished = {Supercomputing '93 poster session}, keywords = {file system, parallel I/O, disk layout, pario-bib}, comment = {These two guys from NCAR redid the block allocation strategy routine on the Cray. Current strategy uses round-robin among the disks, using a different disk for each allocation request. Each request looks for blocks on that disk, until it is satisfied or space runs out, and then goes to the next disk. It uses a free-block bitmap to find the blocks. Problem: too many extents, not enough contiguity. These guys tried first-bit and best-fit from all extents on all disks. First-fit had faster allocation time, of course, and both had much lower file fragmentation. They also used the vector hardware to search the bitmap for non-zero words.} }