mkfs_sfs(1M)

Synopsis

Description

mkfs constructs a file system by writing on the special file special unless the `-o N' flag has been specified. The numeric size specifies the number of logical 512 byte sectors in the file system. mkfs builds a file system with a root directory and a lost+found directory (see fsck(1M)). The number of inodes is calculated as a function of the file system size.

sfs-specific options

-F sfs

Specifies the sfs-FSType.

-o

Specify the sfs specific options. These options can be specified in any order, but must be separated by commas. The following options are available:

M

Specifies that the root of the file system is to be a multilevel directory.

N

Do not write the file system to the special file. This suboption gives all the information needed to create a file system but does not create it.

nsect=n

n is the number of sectors per track on the disk. The default is 18.

ntrack=n

n is the number of tracks per cylinder on the disk. The default is 9.

bsize=n

The primary block size for files on the file system. n must be a power of two, currently selected from 2048 or 8192 (the default). The default block size will be the same as the machine page size, unless the page size is less than 2048, in which case the default block size is 2048.

fragsize=n

The fragment size for files on the file system. n represents the smallest amount of disk space that will be allocated to a file. It must be a power of two currently selected from the range 512 to 8192. The default fragment size will equal the block size if the block size is less than or equal to 2048; otherwise, it is 1024.

cgsize=n

The number of disk cylinders per cylinder group. n must be in the range 1 to 32. cgsize has different defaults, depending on the size of the cylinder group. If the cylinder group is less than 3/4 MB, cgsize defaults to 16. If the cylinder group is between 3/4 and 1.5 MB, cgsize defaults to 12. If the cylinder group is greater than 1.5 MB, cgsize defaults to 8.

rps=n

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

nbpi=n

n is the number of bytes for which one inode block is allocated. This parameter is currently set at one inode block for every 1024 bytes.

opt=s|t

Space or time optimization preference; s specifies optimization for space, t specifies optimization for time. The default is t.

apc=n

n is the number of alternates per cylinder (SCSI devices only). The default is 0.

gap=n

n is the expected time (in milliseconds) to service a transfer completion interrupt and initiate a new transfer on the same disk. It is used to decide how much rotational spacing to place between successive blocks in a file. The default is 4.

C

Some applications that pre-date SVR4 do not work on file systems with more than 64K inodes. Therefore, when the number of inodes for the file system being built exceeds the 64K limit, mkfs prompts the user to confirm that he or she indeed wants the large number of inodes. The -o C option silences this mkfs prompt and limits the number of inodes to a maximum of 64K, ensuring perfect binary compatibility with the pre-Release 4 UNIX System.

L

When the number of inodes for the file system being built exceeds the 64K limit, mkfs prompts the user to confirm that he or she indeed wants the large number of inodes. The -o L option silences this prompt and allows the user to create a file system with more than 64K inodes.

special

mkfs constructs a file system by writing on the special file.

size

Specify the number of logical 512 byte sectors in the file system. The largest file size is a maximum of 4,194,304 512-byte sectors (2 gigbytes).

References

Notices

You should keep a note of spare superblock copies in the ufs file system, so that in the event of superblock corruption, you will know which blocks contain spare entries.