181 ;;Quote: description of new file system for UNIX 4.2bsd

184 ;;Quote: UNIX file system described by a replicated, immutable superblock

184 ;;Quote: UNIX uses at least 4K file blocks; allows 4 gigabyte files with two levels of indirection

184 ;;Quote: UNIX partitions disks into cylinder groups with copy of superblock, local inodes, free block bit map, and usage statistics

184 ;;Quote: a UNIX cylinder group preallocates an inode for every 2K bytes of disk; far more than needed

184 ;;Quote: bookkeeping information for a UNIX cylinder group is staggered to prevent a lost platter from destroying everything

185 ;;Quote: UNIX file as zero or more data blocks plus fragmented blocks; e.g., 1K fragments of 4K data blocks

185 ;;Quote: free disk bit map for UNIX at fragment level, but blocks are aligned

185+;;Quote: smallest UNIX fragment is a disk sector; need about 5% free disk space

186 ;;Quote: files should be extended one block at a time, with fragment at end; UNIX tells applications the optimal read/write size

188 ;;Quote: UNIX file system allocation accounts for block interleave; divides cylinder group into 8 rotational groups

189 ;;Quote: UNIX directories on different cylinder groups; inodes in a directory in the same group; at most 16 disk transfers for inodes of cylinder group

189 ;;Quote: large UNIX files spread across cylinder groups by new group at 48K bytes and every megabyte

190 ;;Quote: overflow UNIX allocation by rotational closest in cylinder, in same group, rehash to another group, exhaustive search

192 ;;Quote: about 40% of I/O time in UNIX is copying between system and user buffers

192+;;Quote: UNIX does not remap user buffers for I/O since requires page alignment and data would disappear after a write