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mkfs                         Command                         mkfs




Make a new file system

/eettcc/mmkkffss _f_i_l_e_s_y_s_t_e_m _p_r_o_t_o

mkfs makes  a new file system.  filesystem  names the file (norm-
ally a block special file) where the new file system will reside.
The contents  of the newly  created file system  are described in
proto.  proto can be either a number or a file name.

If proto  is a  number, mkfs creates  an empty file  system (con-
taining only  a root  directory) of the  size in blocks  given by
proto.  The  number of i-nodes  is calculated as  a percentage of
this number.  The command


        /etc/mkfs /dev/fha0 2400


creates a  file system on  a high-density, 5.25-inch  diskette in
drive 0.   If the disk is a  high-density, 3.5-inch diskette, use
the command:


        /etc/mkfs /dev/fva0 2880


If proto is a file name,  however, the contents of that file will
be used  as a prototype  for modeling the new  file system.  This
prototype file must be laid out in the following manner:


     _b_o_o_t_s_t_r_a_p__f_i_l_e__n_a_m_e  _f_i_l_e__s_y_s_t_e_m__n_a_m_e  _d_e_v_i_c_e__n_a_m_e
     _n_o.__o_f__b_l_o_c_k_s  _n_o.__o_f__i-_n_o_d_e_s  _m  _n
     %_b _X_X _X_X _X_X
     ...
     _d_i_r_e_c_t_o_r_y__n_a_m_e
             _d_i_r_e_c_t_o_r_y__n_a_m_e _m_o_d_e _u_s_e_r__i_d _g_r_o_u_p__i_d _c_o_n_t_e_n_t_s
             ...
             $
     $


Each line is described below.

The first  line has three fields.   Field 1, bootstrap_file_name,
contains the name of a file that holds the boot strap, which must
fit into  block 0 of the disk.   Field 2, file_system_name, gives
the name of the file  system; and field 3, device_name, gives the
name of  file system's  physical device (for  example, /ddeevv/hhdd11).
Only the  first six characters in  fields 2 and  the  first 11 in
field 3 are significant; all characters after them are ignored.

The second  line contains  four fields.  Field  1, no._of_blocks,
gives the  size of the  file system in blocks;  field 2, no_of_i-


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mkfs                         Command                         mkfs



nodes, gives  the number of i-nodes in  the file system.  Because
each  file   or  directory  requires  one   i-node,  this  number
represents the  limit on the number of files  that may be created
in the file system.  A ratio of seven blocks per i-node generally
works well.  Fields 3 and 4 control interleaving on your disk.  m
tells the  system how many blocks to skip  when it increments the
virtual block  number.  n is the size  of a ``virtual cylinder''.
All the blocks on a virtual cylinder will be allocated before ad-
vancing to  the next virtual  cylinder.  The value of  _n need not
correspond to  the size of  an actual cylinder,  although perfor-
mance is  improved when it does.   m and n are  specific for your
hardware.

Next, the third line and following begin with %bb.  These list the
bad blocks on your storage device.  One or more block numbers may
appear on each line,  separated by white space.  These blocks are
allocated to the bad block file (i-node 1).

The remaining  lines in the  _p_r_o_t_o file define  the names, modes,
and contents  of the  directories and  files in the  file system.
These  lines are  divided into  fields  separated by  white space
(blanks or tabs) as follows:

*  The  first field  names the file  or directory to  be created.
   This field  is missing on the first  line, which describes the
   root directory of the file system.

*  The second field describes the  mode of the file, which is six
   characters  long.  The  first character  gives the  file type,
   that is, whether  the file is ordinary (`-'), directory (`d'),
   block special (`b'),   or character special (`c').  The second
   character is `u' for set user id on execution,  and `-' other-
   wise.  The  third character is `g' for set  group id on execu-
   tion,  and `-' otherwise.  Characters 4 through 6 specify per-
   missions in  octal; for example, 664444  specifies read and write
   permission for the owner, read permission for other users from
   the  same group,  and  read permission  for  users from  other
   groups.
   If the above file  type were a directory, subsequent files are
   recursively  defined under that  directory, until  the current
   level of  directory is terminated  by a line  containing a `$'
   character.

*  The next two fields  specify the owner's numerical user id and
   group id.

*  The  last field describes file contents.   For a directory, it
   is not  needed.  For  an ordinary  file, it is  the name  of a
   COHERENT file that will be copied into the newly created file.
   For  block or  character-special files,  there are  two fields
   that specify the numbers of the major and minor devices.

Finally, each  directory's description and the  entire _p_r_o_t_o file
must terminate with dollar signs `$'.



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mkfs                         Command                         mkfs



The  proto  file  need  not  contain  all of  the  above  fields.
However, it must contain the name of the boot block (line 1), the
number of blocks and the number  of i-nodes (line 2), the list of
bad blocks,  the name of  at least one directory,  and the dollar
sign that ends the file.

The following example  specifies a proto file for a high-density,
5.25-inch floppy  disk; note that this floppy  disk is faulty and
contains a number of bad blocks:


/conf/boot.fha
2400 100
%b 55
%b 185 86
d--755 3 1
     coherent ---644 3 1 /coherent
     tmp     d--777 3 1
     $
     bin     d--755 3 1
             mail   -u-755 0 1 /bin/mail
     $
     dev     d--755 3 1
             tty30  c--644 0 1 3 0
             tty35  c--644 0 1 3 5
             mt0    b--600 0 1 12 0
     $
$


You can use the command badscan to draw up the list of bad blocks
on your disk and create a skeleton _p_r_o_t_o file.

***** See Also  ***** badscan, chmod, commands, fsck, mount, res-
tor, unmkfs

***** Diagnostics *****

Diagnostic  message  are generated  for  badly constructed  proto
files or for I/O errors on the file system.

















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