Copyright (c) 2001 Dima Dorfman.
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$FreeBSD: releng/11.0/sbin/mdmfs/mdmfs.8 296648 2016-03-11 06:07:09Z ak $
.Dd March 9, 2016 .Dt MDMFS 8 .Os .Sh NAME .Nm mdmfs , .Nm mount_mfs .Nd configure and mount an in-memory file system using the .Xr md 4 driver .Sh SYNOPSIS .Nm .Op Fl DLlMNnPStTUX .Op Fl a Ar maxcontig .Op Fl b Ar block-size .Op Fl c Ar blocks-per-cylinder-group .Op Fl d Ar max-extent-size .Op Fl E Ar path-mdconfig .Op Fl e Ar maxbpg .Op Fl F Ar file .Op Fl f Ar frag-size .Op Fl i Ar bytes .Op Fl m Ar percent-free .Op Fl O Ar optimization .Op Fl o Ar mount-options .Op Fl p Ar permissions .Op Fl s Ar size .Op Fl T Ar fstype .Op Fl v Ar version .Op Fl w Ar user : Ns Ar group .Ar md-device .Ar mount-point .Sh DESCRIPTION The .Nm utility is designed to be a work-alike and look-alike of the deprecated .Xr mount_mfs 8 . The end result is essentially the same, but is accomplished in a completely different way. The .Nm utility configures an .Xr md 4 disk using .Xr mdconfig 8 , puts a UFS file system on it (unless .Fl P was specified) using .Xr newfs 8 , and mounts it using .Xr mount 8 . It can handle .Xr geom_uzip 4 compressed disk images, as long as the kernel supports this GEOM class. All the command line options are passed to the appropriate program at the appropriate stage in order to achieve the desired effect.
p By default, .Nm creates a swap-based
q Dv MD_SWAP disk with soft-updates enabled and mounts it on .Ar mount-point . It uses the .Xr md 4 device specified by .Ar md-device . If .Ar md-device is .Ql md (no unit number), it will use .Xr md 4 Ns 's auto-unit feature to automatically select an unused device. Unless otherwise specified with one of the options below, it uses the default arguments to all the helper programs.
p The following options are available. Where possible, the option letter matches the one used by .Xr mount_mfs 8 for the same thing. l -tag -width indent t Fl a Ar maxcontig Specify the maximum number of contiguous blocks that will be laid out before forcing a rotational delay (see the .Fl d option). t Fl b Ar block-size The block size of the file system, in bytes. t Fl c Ar blocks-per-cylinder-group The number of blocks per cylinder group in the file system. t Fl D If not using auto-unit, do not run .Xr mdconfig 8 to try to detach the unit before attaching it. t Fl d Ar max-extent-size The file system may choose to store large files using extents. This parameter specifies the largest extent size that may be used. It is presently limited to its default value which is 16 times the file system blocksize. t Fl E Ar path-mdconfig Use .Ar path-mdconfig as a location of the .Xr mdconfig 8 utility. t Fl e Ar maxbpg Indicate the maximum number of blocks any single file can allocate out of a cylinder group before it is forced to begin allocating blocks from another cylinder group. t Fl F Ar file Create a vnode-backed
q Dv MD_VNODE memory disk backed by .Ar file . t Fl f Ar frag-size The fragment size of the file system in bytes. t Fl i Ar bytes Number of bytes per inode. t Fl l Enable multilabel MAC on the new file system. t Fl L Show the output of the helper programs. By default, it is sent to
a /dev/null . t Fl M Create a .Xr malloc 9 backed disk
q Dv MD_MALLOC instead of a swap-backed disk. t Fl m Ar percent-free The percentage of space reserved for the superuser. t Fl N Do not actually run the helper programs. This is most useful in conjunction with .Fl X . t Fl n Do not create a
a .snap directory on the new file system. t Fl O Ar optimization Select the optimization preference; valid choices are .Cm space and .Cm time , which will optimize for minimum space fragmentation and minimum time spent allocating blocks, respectively. t Fl o Ar mount-options Specify the mount options with which to mount the file system. See .Xr mount 8 for more information. t Fl P Preserve the existing file system; do not run .Xr newfs 8 . This only makes sense if .Fl F is specified to create a vnode-backed disk. t Fl p Ar permissions Set the file (directory) permissions of the mount point .Ar mount-point to .Ar permissions . The .Ar permissions argument can be in any of the mode formats recognized by .Xr chmod 1 . If symbolic permissions are specified, the operation characters .Dq + and .Dq - are interpreted relative to the initial permissions of .Dq a=rwx . t Fl S Do not enable soft-updates on the file system. t Fl s Ar size Specify the size of the disk to create. This only makes sense if .Fl F is .Em not specified. That is, this will work for the default swap-backed
q Dv MD_SWAP disks, and the optional
q Fl M .Xr malloc 9 backed disks
q Dv MD_MALLOC . t Fl t Turn on the TRIM enable flag for .Xr newfs 8 . When used with a file system that issue BIO_DELETE bio requests, .Xr md 4 returns deleted blocks to the system memory pool. t Fl T Ar fstype Specify a file system type for a vnode-backed memory disk. Any file system supported by .Xr mount 8 command can be specified. This option only makes sense when .Fl F and .Fl P are used. t Fl U Enable soft-updates on the file system. This is the default, and is accepted only for compatibility. It is only really useful to negate the .Fl S flag, should such a need occur. t Fl v Ar version Specify the UFS version number for use on the file system; it may be either .Dv 1 or .Dv 2 . The default is derived from the default of the .Xr newfs 8 command. t Fl w Ar user : Ns Ar group Set the owner and group to .Ar user and .Ar group , respectively. The arguments have the same semantics as with .Xr chown 8 , but specifying just a .Ar user or just a .Ar group is not supported. t Fl X Print what command will be run before running it, and other assorted debugging information. .El
p The .Fl F and .Fl s options are passed to .Xr mdconfig 8 as .Fl f and .Fl s , respectively. The .Fl a , b , c , d , e , f , i , m and .Fl n options are passed to .Xr newfs 8 with the same letter. The .Fl O option is passed to .Xr newfs 8 as .Fl o . The .Fl o option is passed to .Xr mount 8 with the same letter. The .Fl T option is passed to .Xr mount 8 as .Fl t . See the programs that the options are passed to for more information on their semantics. .Sh EXAMPLES Create and mount a 32 megabyte swap-backed file system on
a /tmp :
p .Dl "mdmfs -s 32m md /tmp"
p The same file system created as an entry in
p .Dl "md /tmp mfs rw,-s32m 2 0"
p Create and mount a 16 megabyte malloc-backed file system on
a /tmp using the
a /dev/md1 device; furthermore, do not use soft-updates on it and mount it .Cm async :
p .Dl "mdmfs -M -S -o async -s 16m md1 /tmp"
p Create and mount a .Xr geom_uzip 4 based compressed disk image:
p .Dl "mdmfs -P -F foo.uzip -oro md.uzip /tmp/"
p Mount the same image, specifying the
p .Dl "mdmfs -P -F foo.uzip -oro md1.uzip /tmp/"
p Configure a vnode-backed file system and mount its first partition, using automatic device numbering:
p .Dl "mdmfs -P -F foo.img mds1a /tmp/"
p Mount a vnode-backed cd9660 file system using automatic device numbering:
p .Dl "mdmfs -T cd9660 -P -F foo.iso md /tmp" .Sh COMPATIBILITY The .Nm utility, while designed to be compatible with .Xr mount_mfs 8 , can be useful by itself. Since .Xr mount_mfs 8 had some silly defaults, a .Dq compatibility mode is provided for the case where bug-to-bug compatibility is desired.
p Compatibility is enabled by starting .Nm with the name .Li mount_mfs or .Li mfs (as returned by .Xr getprogname 3 ) . In this mode, the following behavior, as done by .Xr mount_mfs 8 , is duplicated: l -bullet -offset indent t The file mode of .Ar mount-point is set by default to .Li 01777 as if .Fl p Ar 1777 was given on the command line. .El .Sh SEE ALSO .Xr md 4 , .Xr fstab 5 , .Xr mdconfig 8 , .Xr mount 8 , .Xr newfs 8 .Sh AUTHORS .An Dima Dorfman