diff options
Diffstat (limited to 'share/man/man5/fs.5')
| -rw-r--r-- | share/man/man5/fs.5 | 43 |
1 files changed, 24 insertions, 19 deletions
diff --git a/share/man/man5/fs.5 b/share/man/man5/fs.5 index 53aa5a59e9b..fde8eac456b 100644 --- a/share/man/man5/fs.5 +++ b/share/man/man5/fs.5 @@ -1,3 +1,4 @@ +.\" $OpenBSD: fs.5,v 1.4 1998/11/26 04:25:58 aaron Exp $ .\" $NetBSD: fs.5,v 1.3 1994/11/30 19:31:17 jtc Exp $ .\" .\" Copyright (c) 1983, 1991, 1993 @@ -172,14 +173,15 @@ super-block data does not change, so the copies need not be referenced further unless disaster strikes. .Pp Addresses stored in inodes are capable of addressing fragments -of `blocks'. File system blocks of at most size +of +.Dq blocks . +File system blocks of at most size .Dv MAXBSIZE can be optionally broken into 2, 4, or 8 pieces, each of which is addressable; these pieces may be .Dv DEV_BSIZE , -or some multiple of -a +or some multiple of a .Dv DEV_BSIZE unit. .Pp @@ -190,7 +192,7 @@ necessary. The file system format retains only a single pointer to such a fragment, which is a piece of a single large block that has been divided. The size of such a fragment is determinable from information in the inode, using the -.Fn blksize fs ip lbn +.Fn blksize macro. .Pp The file system records space availability at the fragment level; @@ -228,14 +230,18 @@ The element specifies whether the file system should try to minimize the time spent allocating blocks, or if it should attempt to minimize the space fragmentation on the disk. -If the value of fs_minfree (see above) is less than 5%, +If the value of +.Fa fs_minfree +(see above) is less than 5%, then the file system defaults to optimizing for space to avoid running out of full sized blocks. -If the value of minfree is greater than or equal to 5%, +If the value of +.Fa fs_minfree +is greater than or equal to 5%, fragmentation is unlikely to be problematical, and the file system defaults to optimizing for time. .Pp -.Em Cylinder group related limits : +.Ss Cylinder group related limits Each cylinder keeps track of the availability of blocks at different rotational positions, so that sequential blocks can be laid out with minimum rotational latency. With the default of 8 distinguished @@ -268,7 +274,7 @@ it is possible to create files of size .Dv MINBSIZE must be big enough to hold a cylinder group block, thus changes to -.Pq Fa struct cg +.Fa struct cg must keep its size within .Dv MINBSIZE . Note that super-blocks are never more than size @@ -293,20 +299,18 @@ These blocks are read in from .Fa fs_cssize ) in addition to the super-block. .Pp -.Sy N.B.: -.Xr sizeof Pq Fa struct csum +Note that +.Fn sizeof "struct csum" must be a power of two in order for the .Fn fs_cs macro to work. .Pp -The -.Em "Super-block for a file system" : +.Ss Super-block for a file system The size of the rotational layout tables is limited by the fact that the super-block is of size .Dv SBSIZE . -The size of these tables is -.Em inversely +The size of these tables is inversely proportional to the block size of the file system. The size of the tables is increased when sector sizes are not powers of two, @@ -315,17 +319,16 @@ included before the rotational pattern repeats .Pq Fa fs_cpc . The size of the rotational layout tables is derived from the number of bytes remaining in -.Pq Fa struct fs . +.Fa struct fs . .Pp The number of blocks of data per cylinder group is limited because cylinder groups are at most one block. The inode and free block tables must fit into a single block after deducting space for the cylinder group structure -.Pq Fa struct cg . +.Fa struct cg . .Pp -The -.Em Inode : +.Ss Inodes The inode is the focus of all file activity in the .Tn UNIX file system. @@ -333,7 +336,9 @@ There is a unique inode allocated for each active file, each current directory, each mounted-on file, text file, and the root. -An inode is `named' by its device/i-number pair. +An inode is +.Dq named +by its device/i-number pair. For further information, see the include file .Aq Pa ufs/ufs/inode.h . .Sh HISTORY |