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mkfs_ufs(1M)		System Administration Commands		  mkfs_ufs(1M)

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 system, 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 parameters.

	   calcsb

	       Sends to stdout a human-readable version of the superblock that
	       would be used to create a file system with the  specified  con‐
	       figuration parameters.

	   cgsize=n

	       The  number of cylinders per cylinder group, ranging from 16 to
	       256. The default is calculated by dividing the number  of  sec‐
	       tors 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	 allo‐
	       cated  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-lim‐
	       its 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%, inclu‐
	       sively.

	       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  calculated  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 eventual	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
	       explicitly 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 cre‐
	       ate 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-sepa‐
	   rated 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 attributes:

       ┌─────────────────────────────┬─────────────────────────────┐
       │      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  cannot  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  performance.	 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  condition	 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	 lofi‐
       adm(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.

SunOS 5.10			  8 Mar 2006			  mkfs_ufs(1M)
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