Solaris

mkfs -m <myRootFS>

mkfs -F ufs -o nsect=128,ntrack=48,bsize=8192,fragsize=1024,cgsize=16,free=1,rps=120,nbpi=8155,opt=t,apc=0,gap=0,nrpos=8,maxcontig=128,mtb=n <myRootFS>

/*
 * The inode is used to describe each active (or recently active) file in the
 * UFS filesystem. It is composed of two types of information. The first part
 * is the information that is needed only while the file is active (such as
 * the identity of the file and linkage to speed its lookup). The second part
 * is the permanent meta-data associated with the file which is read in
 * from the permanent dinode from long term storage when the file becomes
 * active, and is put back when the file is no longer being used.
 *
 * An inode may only be changed while holding either the exclusive
 * vnode lock or the shared vnode lock and the vnode interlock. We use
 * the latter only for "read" and "get" operations that require
 * changing i_flag, or a timestamp. This locking protocol allows executing
 * those operations without having to upgrade the vnode lock from shared to
 * exclusive.
 */
struct inode {
    TAILQ_ENTRY(inode) i_nextsnap; /* snapshot file list. */
    struct    vnode  *i_vnode;/* Vnode associated with this inode. */
    struct    ufsmount *i_ump;/* Ufsmount point associated with this inode. */
    u_int32_t i_flag;    /* flags, see below */
    struct cdev *i_dev;    /* Device associated with the inode. */
    ino_t      i_number;    /* The identity of the inode. */
    int      i_effnlink;    /* i_nlink when I/O completes */

    struct     fs *i_fs;    /* Associated filesystem superblock. */
    struct     dquot *i_dquot[MAXQUOTAS]; /* Dquot structures. */
    /*
     * Side effects; used during directory lookup.
     */
    int32_t      i_count;    /* Size of free slot in directory. */
    doff_t      i_endoff;    /* End of useful stuff in directory. */
    doff_t      i_diroff;    /* Offset in dir, where we found last entry. */
    doff_t      i_offset;    /* Offset of free space in directory. */

    union {
        struct dirhash *dirhash; /* Hashing for large directories. */
        daddr_t *snapblklist;    /* Collect expunged snapshot blocks. */
    } i_un;

    /*
     * Data for extended attribute modification.
      */
    u_char      *i_ea_area;    /* Pointer to malloced copy of EA area */
    unsigned  i_ea_len;    /* Length of i_ea_area */
    int      i_ea_error;    /* First errno in transaction */
    int      i_ea_refs;    /* Number of users of EA area */

    /*
     * Copies from the on-disk dinode itself.
     */
    u_int16_t i_mode;    /* IFMT, permissions; see below. */
    int16_t      i_nlink;    /* File link count. */
    u_int64_t i_size;    /* File byte count. */
    u_int32_t i_flags;    /* Status flags (chflags). */
    int64_t      i_gen;    /* Generation number. */
    u_int32_t i_uid;    /* File owner. */
    u_int32_t i_gid;    /* File group. */
    /*
     * The real copy of the on-disk inode.
     */
    union {
        struct ufs1_dinode *din1;    /* UFS1 on-disk dinode. */
        struct ufs2_dinode *din2;    /* UFS2 on-disk dinode. */
    } dinode_u;
};

/*
 * A UFS1 dinode contains all the meta-data associated with a UFS1 file.
 * This structure defines the on-disk format of a UFS1 dinode. Since
 * this structure describes an on-disk structure, all its fields
 * are defined by types with precise widths.
 */
struct ufs1_dinode {
    u_int16_t    di_mode;    /*   0: IFMT, permissions; see below. */
    int16_t        di_nlink;    /*   2: File link count. */
    union {
        u_int16_t oldids[2];    /*   4: Ffs: old user and group ids. */
    } di_u;
    u_int64_t    di_size;    /*   8: File byte count. */
    int32_t        di_atime;    /*  16: Last access time. */
    int32_t        di_atimensec;    /*  20: Last access time. */
    int32_t        di_mtime;    /*  24: Last modified time. */
    int32_t        di_mtimensec;    /*  28: Last modified time. */
    int32_t        di_ctime;    /*  32: Last inode change time. */
    int32_t        di_ctimensec;    /*  36: Last inode change time. */
    ufs1_daddr_t    di_db[NDADDR];    /*  40: Direct disk blocks. */
    ufs1_daddr_t    di_ib[NIADDR];    /*  88: Indirect disk blocks. */
    u_int32_t    di_flags;    /* 100: Status flags (chflags). */
    int32_t        di_blocks;    /* 104: Blocks actually held. */
    int32_t        di_gen;        /* 108: Generation number. */
    u_int32_t    di_uid;        /* 112: File owner. */
    u_int32_t    di_gid;        /* 116: File group. */
    u_int64_t    di_modrev;    /* 120: i_modrev for NFSv4 */
};

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.

struct dinode {
    279     union {
    280         struct    icommon di_icom;
    281         char    di_size[128];
    282     } di_un;
    283 };