4.4BSD/usr/share/man/cat8/mfs.0
NEWFS(8) BSD System Manager's Manual NEWFS(8)
NNAAMMEE
nneewwffss, mmffss - construct a new file system
SSYYNNOOPPSSIISS
nneewwffss [--NN] [_n_e_w_f_s_-_o_p_t_i_o_n_s] _s_p_e_c_i_a_l
mmoouunntt__mmffss [--FF _m_o_u_n_t___f_l_a_g_s] [_n_e_w_f_s_-_o_p_t_i_o_n_s] _s_p_e_c_i_a_l _n_o_d_e
DDEESSCCRRIIPPTTIIOONN
NNeewwffss replaces the more obtuse mkfs(8) program. Before running nneewwffss or
mmoouunntt__mmffss, the disk must be labeled using disklabel(8). NNeewwffss builds a
file system on the specified special device basing its defaults on the
information in the disk label. Typically the defaults are reasonable,
however nneewwffss has numerous options to allow the defaults to be selective-
ly overridden.
MMoouunntt__mmffss is used to build a file system in virtual memory and then mount
it on a specified node. MMoouunntt__mmffss exits and the contents of the file
system are lost when the file system is unmounted. If mmoouunntt__mmffss is sent
a signal while running, for example during system shutdown, it will at-
tempt to unmount its corresponding file system. The parameters to
mmoouunntt__mmffss are the same as those to nneewwffss. The special file is only used
to read the disk label which provides a set of configuration parameters
for the memory based file system. The special file is typically that of
the primary swap area, since that is where the file system will be backed
up when free memory gets low and the memory supporting the file system
has to be paged.
The following options define the general layout policies.
--NN Causes the file system parameters to be printed out without
really creating the file system.
--OO Creates an 4.3BSD format filesystem. This options is primar-
ily used to build root filesystems that can be understood by
older boot ROMs.
--bb _b_l_o_c_k_-_s_i_z_e
The block size of the file system in bytes.
--ff _f_r_a_g_-_s_i_z_e
The fragment size of the file system in bytes.
--mm _f_r_e_e _s_p_a_c_e _%
The percentage of space reserved from normal users; the mini-
mum free space threshold. The default value used is 10%.
See tunefs(8) for more details on how to set this option.
--oo _o_p_t_i_m_i_z_a_t_i_o_n _p_r_e_f_e_r_e_n_c_e
(``space'' or ``time'') The file system can either be in-
structed to try to minimize the time spent allocating blocks,
or to try to minimize the space fragmentation on the disk.
If the value of minfree (see above) is less than 10%, the de-
fault is to optimize for space; if the value of minfree
greater than or equal to 10%, the default is to optimize for
time. See tunefs(8) for more details on how to set this op-
tion.
--aa _m_a_x_c_o_n_t_i_g
This specifies the maximum number of contiguous blocks that
will be laid out before forcing a rotational delay (see --dd
below). The default value is one. See tunefs(8) for more
details on how to set this option.
--dd _r_o_t_d_e_l_a_y
This specifies the expected time (in milliseconds) to service
a transfer completion interrupt and initiate a new transfer
on the same disk. The default is 4 milliseconds. See
tunefs(8) for more details on how to set this option.
--ee _m_a_x_b_p_g This indicates the maximum number of blocks any single file
can allocate out of a cylinder group before it is forced to
begin allocating blocks from another cylinder group. The de-
fault is about one quarter of the total blocks in a cylinder
group. See tunefs(8) for more details on how to set this op-
tion.
--ii _n_u_m_b_e_r _o_f _b_y_t_e_s _p_e_r _i_n_o_d_e
This specifies the density of inodes in the file system. The
default is to create an inode for each 2048 bytes of data
space. If fewer inodes are desired, a larger number should
be used; to create more inodes a smaller number should be
given.
--cc _#_c_y_l_i_n_d_e_r_s_/_g_r_o_u_p
The number of cylinders per cylinder group in a file system.
The default value used is 16.
--ss _s_i_z_e The size of the file system in sectors.
The following options override the standard sizes for the
disk geometry. Their default values are taken from the disk
label. Changing these defaults is useful only when using
nneewwffss to build a file system whose raw image will eventually
be used on a different type of disk than the one on which it
is initially created (for example on a write-once disk).
Note that changing any of these values from their defaults
will make it impossible for fsck to find the alternate su-
perblocks if the standard super block is lost.
--rr _r_e_v_o_l_u_t_i_o_n_s_/_m_i_n_u_t_e
The speed of the disk in revolutions per minute.
--SS _s_e_c_t_o_r_-_s_i_z_e
The size of a sector in bytes (almost never anything but
512).
--uu _s_e_c_t_o_r_s_/_t_r_a_c_k
The number of sectors per track available for data allocation
by the file system. This does not include sectors reserved
at the end of each track for bad block replacement (see --pp
below).
--tt _#_t_r_a_c_k_s_/_c_y_l_i_n_d_e_r
The number of tracks/cylinder available for data allocation
by the file system.
--pp _s_p_a_r_e _s_e_c_t_o_r_s _p_e_r _t_r_a_c_k
Spare sectors (bad sector replacements) are physical sectors
that occupy space at the end of each track. They are not
counted as part of the sectors/track (--uu) since they are not
available to the file system for data allocation.
--xx _s_p_a_r_e _s_e_c_t_o_r_s _p_e_r _c_y_l_i_n_d_e_r
Spare sectors (bad sector replacements) are physical sectors
that occupy space at the end of the last track in the cylin-
der. They are deducted from the sectors/track (--uu) of the
last track of each cylinder since they are not available to
the file system for data allocation.
--ll _h_a_r_d_w_a_r_e _s_e_c_t_o_r _i_n_t_e_r_l_e_a_v_e
Used to describe perturbations in the media format to compen-
sate for a slow controller. Interleave is physical sector
interleave on each track, specified as the denominator of the
ratio:
sectors read/sectors passed over
Thus an interleave of 1/1 implies contiguous layout, while
1/2 implies logical sector 0 is separated by one sector from
logical sector 1.
--kk _s_e_c_t_o_r _0 _s_k_e_w, _p_e_r _t_r_a_c_k
Used to describe perturbations in the media format to compen-
sate for a slow controller. Track skew is the offset of sec-
tor 0 on track N relative to sector 0 on track N-1 on the
same cylinder.
The following option applies only to mmoouunntt__mmffss.
--FF _m_o_u_n_t _f_l_a_g_s
Used to pass in a decimal numeric value to be passed as mount
flags when running as a memory based file system. This op-
tion is primarily intended for use when mmoouunntt__mmffss is started
by the mount(8) command.
SSEEEE AALLSSOO
disktab(5), fs(5), dumpfs(8), disklabel(8), diskpart(8), fsck(8),
format(8), tunefs(8)
M. McKusick, W. Joy, S. Leffler, and R. Fabry, "A Fast File System for
UNIX,", _A_C_M _T_r_a_n_s_a_c_t_i_o_n_s _o_n _C_o_m_p_u_t_e_r _S_y_s_t_e_m_s _2, 3, pp 181-197, August
1984, (reprinted in the BSD System Manager's Manual).
HHIISSTTOORRYY
The nneewwffss command appeared in 4.2BSD.
4.2 Berkeley Distribution June 5, 1993 3