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mkfs_ufs


NAME
     mkfs_ufs - construct a UFS file system

SYNOPSIS
     mkfs -F ufs  [generic_options]  [-o FSType_specific_options]
     raw_device_file [size]

DESCRIPTION
     The UFS-specific module of mkfs builds  a  UFS  file  system
     with  a  root  directory  and  a  lost+found  directory (see
     fsck(1M)).

     The UFS-specific  mkfs  is  rarely  run  directly.  Use  the
     newfs(1M) command instead.

     raw_device_file indicates the disk  partition  on  which  to
     create  the  new file system. If the -o N, -V, or -m options
     are specified, the raw_device_file is not actually modified.
     size  specifies  the number of disk sectors in the file sys-
     tem, where a disk sector is usually 512 bytes. This argument
     must  follow  the  raw_device_file  argument and is required
     (even with -o N), unless the -V or -m  generic  options  are
     specified.

     generic_options are supported by the generic  mkfs  command.
     See mkfs(1M) for a description of these options.

OPTIONS
     The following generic options are supported:

     -m              Print the command  line  that  was  used  to
                     create the existing file system.



     -V              Print the current mkfs command line.



OPTIONS
     The following UFS-specific options are supported:

     -o

         Use one or more of the  following  values  separated  by
         commas  (with  no  intervening  spaces)  to specify UFS-
         specific options:

         apc=n

             The number of  alternate  sectors  per  cylinder  to
             reserve  for  bad block replacement for SCSI devices
             only. The default is 0.

             This option is not applicable  for  disks  with  EFI
             labels and is ignored.




         bsize=n

             The logical block size of the file system in  bytes,
             either  4096 or 8192. The default is 8192. The sun4u
             architecture does not support the 4096 block size.



         calcbinsb

             Sends to stdout a binary (machine-readable)  version
             of  the  superblock  that  would be used to create a
             file system with the specified configuration parame-
             ters.



         calcsb

             Sends to stdout  a  human-readable  version  of  the
             superblock  that would be used to create a file sys-
             tem with the specified configuration parameters.



         cgsize=n

             The number of cylinders per cylinder group,  ranging
             from  16 to 256. The default is calculated by divid-
             ing the number of sectors in the file system by  the
             number of sectors in a gigabyte. Then, the result is
             multiplied  by  32.  The  default  value  is  always
             between 16 and 256.

             The per-cylinder-group meta data must fit in a space
             no larger than what is available in one logical file
             system block. If too large a cgsize is requested, it
             is changed by the minimum amount necessary.



         fragsize=n

             The smallest amount of disk space in bytes that  can
             be  allocated to a file. fragsize must be a power of
             2 divisor of bsize, where:

             bsize / fragsize is 1, 2, 4, or 8.

             This means that if the logical block size  is  4096,
             legal  values  for fragsize are 512, 1024, 2048, and
             4096. When the logical block  size  is  8192,  legal
             values  are  1024, 2048, 4096, and 8192. The default
             value is 1024.

             For file systems greater than 1 terabyte or for file
             systems  created  with the mtb=y option, fragsize is
             forced to match block size (bsize).



         free=n

             The minimum percentage of free space to maintain  in
             the  file  system  between  0% and 99%, inclusively.
             This space is off-limits to  users.  Once  the  file
             system   is  filled  to  this  threshold,  only  the
             superuser can continue writing to the file system.

             The default is ((64 Mbytes/partition size)  *  100),
             rounded  down  to  the  nearest  integer and limited
             between 1% and 10%, inclusively.

             This parameter can be subsequently changed using the
             tunefs(1M) command.



         gap=n

             Rotational delay. This option  is  obsolete  in  the
             Solaris  10  release.  The value is always set to 0,
             regardless of the input value.



         maxcontig=n

             The maximum number of logical blocks,  belonging  to
             one  file,  that  are  allocated  contiguously.  The
             default is calculated as follows:


             maxcontig = disk drive maximum transfer size / disk block size

             If the disk drive's maximum transfer size cannot  be
             determined,  the default value for maxcontig is cal-
             culated from kernel parameters as follows:

             If maxphys is less  than  ufs_maxmaxphys,  which  is
             typically 1 Mbyte, then maxcontig is set to maxphys.
             Otherwise, maxcontig is set to ufs_maxmaxphys.

             You can set maxcontig to any positive integer value.

             The actual value will be the lesser of what has been
             specified and what the hardware supports.

             You can subsequently change this parameter by  using
             tunefs(1M).



         mtb=y

             Set the parameters of the file system to allow even-
             tual  growth to over a terabyte in total file system
             size. This option sets fragsize to be  the  same  as
             bsize,  and  sets  nbpi  to  1  Mbyte, unless the -i
             option is used to make it even larger. If you expli-
             citly  set the fragsize or nbpi parameters to values
             that are incompatible with this  option,  the  user-
             supplied value of fragsize or nbpi is ignored.



         N

             Print out the file system parameters that  would  be
             used  to  create  the  file  system without actually
             creating the file system.



         nbpi=n

             The number of bytes per inode, which  specifies  the
             density  of inodes in the file system. The number is
             divided into the total size of the  file  system  to
             determine the number of inodes to create.

             This value should reflect the expected average  size
             of  files  in  the  file system. If fewer inodes are
             desired, a larger number should be used.  To  create
             more  inodes,  a smaller number should be given. The
             default is 2048.

             The number of inodes can increase if the file system
             is expanded with the growfs command.



         nrpos=n

             The number  of  different  rotational  positions  in
             which to divide a cylinder group. The default is 8.

             This option is not applicable  for  disks  with  EFI
             labels and is ignored.



         nsect=n

             The number of sectors per track  on  the  disk.  The
             default is 32.



         ntrack=n

             The number of tracks per cylinder on the  disk.  The
             default is 16.

             This option is not applicable  for  disks  with  EFI
             labels and is ignored.



         opt=s|t

             The file system can either be instructed to  try  to
             minimize the time spent allocating blocks, or to try
             to minimize the space fragmentation on the disk. The
             default is time.

             This parameter can be subsequently changed with  the
             tunefs(1M) command.



         rps=n

             The rotational speed of the disk, in revolutions per
             second. The default is 60.

             Note that you specify  rps  for  mkfs  and  rpm  for
             newfs.

             This option is not applicable  for  disks  with  EFI
             labels and is ignored.



         Alternatively, parameters can be entered as  a  list  of
         space-separated  values (without keywords) whose meaning
         is positional. In this case, the -o  option  is  omitted
         and  the  list follows the size operand. This is the way
         newfs passes the parameters to mkfs.


OPERANDS
     The following operands are supported:

     raw_device_file         The  disk  partition  on  which   to
                             write.



ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | SUNWcsu                     |
    |_____________________________|_____________________________|


SEE ALSO
     fsck(1M),  mkfs(1M),  newfs(1M),   tunefs(1M),   dir_ufs(4),
     attributes(5), ufs(7FS)

DIAGNOSTICS
     The following error message typically occurs with very  high
     density disks. On such disks, the file system structure can-
     not encode the proper disk layout information. However, such
     disks  have  enough  onboard intelligence to make up for any
     layout deficiencies, so there is no actual impact on perfor-
     mance.   The  warning that performance might be impaired can
     be safely ignored.

     Warning: insufficient space in super block for
     rotational layout tables with nsect sblock.fs_nsect
     and ntrak sblock.fs_ntrak. (File system performance may be impaired.)

     The following error message occurs when  the  disk  geometry
     results  in  a  situation  where the last truncated cylinder
     group cannot contain the correct number of data blocks. Some
     disk space is wasted.

     Warning: inode blocks/cyl group (grp) >= data blocks (num) in last cylinder

     If there is only one cylinder group and if the above  condi-
     tion holds true, mkfs fails with the following error:

     File system creation failed. There is only one cylinder group and that is
     not even big enough to hold the inodes.

     The following error message occurs when the best  calculated
     file system layout is unable to include the last few sectors
     in the last cylinder group. This is due to  the  interaction
     between  how  much  space is used for various pieces of meta
     data and the total blocks available  in  a  cylinder  group.
     Modifying  nbpi  and cpg might reduce this number, but it is
     rarely worth the effort.

     Warning: num sector(s) in last cylinder group unallocated

NOTES
     You can use lofiadm to create a file  that  appears  to  the
     mkfs  command  (for example, mkfs_pcfs or mkfs_ufs) as a raw
     device. You can then use the mkfs command to create  a  file
     system  on  that  device.  See  lofiadm(1M)  for examples of
     creating a UFS and a  PC  (FAT)  file  system  on  a  device
     created by lofiadm.

     Both the block and character devices,  such  as  devices  in
     /dev/dsk  and  /dev/rdsk, must be available prior to running
     the mkfs command.










Man pages from Solaris 10 Update 8. See docs.sun.com and www.oracle.com for further documentation and Solaris information.
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