MT(1) FreeBSD General Commands Manual MT(1)
NAME
mt - magnetic tape manipulating program
SYNOPSIS
mt [-f tapename] command [count]
mt [-f tapename] command argument
DESCRIPTION
The mt utility is used to command a magnetic tape drive for operations
other than reading or writing data.
The -f option's tapename overrides the TAPE environment variable
described below.
The available commands are listed below. Only as many characters as are
required to uniquely identify a command need be specified.
The following commands optionally take a count, which defaults to 1.
weof Write count end-of-file (EOF) marks at the current position.
This returns when the file mark has been written to the media.
weofi Write count end-of-file (EOF) marks at the current position.
This returns as soon as the command has been validated by the
tape drive.
smk Write count setmarks at the current position (DDS drives
only).
fsf Forward space count files.
fsr Forward space count records.
fss Forward space count setmarks (DDS drives only).
bsf Backward space count files.
bsr Backward space count records.
bss Backward space count setmarks (DDS drives only).
erase Erase the tape using a long (often very long) method. With a
count of 0, it will erase the tape using a quick method.
Operation is not guaranteed if the tape is not at its
beginning. The tape will be at its beginning upon completion.
The following commands ignore count.
rdhpos Read the hardware block position. The block number
reported is specific for that hardware only. With drive
data compression especially, this position may have more
to do with the amount of data sent to the drive than the
amount of data written to tape. Some drives do not
support this.
rdspos Read the SCSI logical block position. This typically is
greater than the hardware position by the number of end-
of-file marks. Some drives do not support this.
rewind Rewind the tape.
offline, rewoffl
Rewind the tape and place the drive off line. Some
drives are never off line.
load Load the tape into the drive.
retension Re-tension the tape. This winds the tape from the
current position to the end and then to the beginning.
This sometimes improves subsequent reading and writing,
particularly for streaming drives. Some drives do not
support this.
ostatus Output status information about the drive. For SCSI
magnetic tape devices, the current operating modes of
density, blocksize, and whether compression is enabled
is reported. The current state of the driver (what it
thinks that it is doing with the device) is reported.
If the driver knows the relative position from BOT (in
terms of filemarks and records), it outputs that. Note
that this information is not definitive (only BOT, End
of Recorded Media, and hardware or SCSI logical block
position (if the drive supports such) are considered
definitive tape positions).
Also note that this is the old status command, and will
be eliminated in favor of the new status command (see
below) in a future release.
errstat Output (and clear) error status information about this
device. For every normal operation (e.g., a read or a
write) and every control operation (e.g,, a rewind), the
driver stores up the last command executed and it is
associated status and any residual counts (if any).
This command retrieves and outputs this information. If
possible, this also clears any latched error
information.
geteotmodel Output the current EOT filemark model. The model states
how many filemarks will be written at close if a tape
was being written.
eod, eom Wind the tape to the end of the recorded data, typically
after an EOF mark where another file may be written.
rblim Report the block limits of the tape drive, including the
minimum and maximum block size, and the block
granularity if any.
The following commands may require an argument.
sethpos Set the hardware block position. The argument is a
hardware block number to which to position the tape.
Some drives do not support this.
setspos Set the SCSI logical block position. The argument is a
SCSI logical block number to which to position the tape.
Some drives do not support this.
blocksize Set the block size for the drive. The argument is the
number of bytes per block, except 0 commands the drive
to use variable-length blocks.
seteotmodel Set the EOT filemark model to argument and output the
old and new models. Typically this will be 2 filemarks,
but some devices (typically QIC cartridge drives) can
only write 1 filemark. You may only choose a value of 1
or 2.
status Output status information about the drive. For SCSI
magnetic tape devices, the current operating modes of
density, blocksize, and whether compression is enabled
is reported. The current state of the driver (what it
thinks that it is doing with the device) is reported.
If the driver knows the relative position from BOT (in
terms of filemarks and records), it outputs that. If
the tape drive supports the long form report of the SCSI
READ POSITION command, the Reported File Number and
Reported Record Number will be numbers other than -1,
and there may be Flags reported as well.
The BOP flag means that the logical position of the
drive is at the beginning of the partition.
The EOP flag means that the logical position of the
drive is between Early Warning and End of Partition.
The BPEW flag means that the logical position of the
drive is in a Programmable Early Warning Zone or on the
EOP side of Early Warning.
Note that the Reported Record Number is the tape block
or object number relative to the beginning of the
partition. The Calculated Record Number is the tape
block or object number relative to the previous file
mark.
Note that the Calculated File and Record Numbers are not
definitive. The Reported File and Record Numbers are
definitive, if they are numbers other than -1.
-v Print additional status information, such as the
maximum supported I/O size.
-x Print all available status data to stdout in XML
format.
getdensity Report density support information for the tape drive
and any media that is loaded. Most drives will report
at least basic density information similar to that
reported by status command. Newer tape drives that
conform to the T-10 SSC and newer tape specifications
may report more detailed information about the types of
tapes they support and the tape currently in the drive.
-x Print all available density data to stdout in
XML format. Because density information is
currently included in the general status XML
report used for mt status command, this will be
the same XML output via "mt status -x"
param Display or set parameters. One of -l, -s, or -x must be
specified to indicate which operation to perform. See
sa(4) for more detailed information on the parameters.
-l List parameters, values and descriptions. By
default all parameters will be displayed. To
display a specific parameter, specify the
parameter with -p.
-p name Specify the parameter name to list (with -l)
or set (with -s).
-q Enable quiet mode for parameter listing. This
will suppress printing of parameter
descriptions.
-s value Specify the parameter value to set. The
general type of this argument (integer,
unsigned integer, string) is determined by the
type of the variable indicated by the sa(4)
driver. More detailed argument checking is
done by the sa(4) driver.
-x Print out all parameter information in XML
format.
protect Display or set drive protection parameters. This is
used to control checking and reporting a per-block
checksum for tape drives that support it. Some drives
may only support some parameters.
-b 0|1 Set the Recover Buffered Data Protected bit.
If set, this indicates that checksums are
transferred with the logical blocks
transferred by the RECOVERED BUFFERED DATA
SCSI command.
-d Disable all protection information settings.
-e Enable all protection information settings.
The default protection method used is Reed-
Solomon CRC (protection method 1), as
specified in ECMA-319. The default protection
information length used with Reed-Solomon CRC
is 4 bytes. To enable all settings except one
more setting, specify the -e argument and then
explicitly disable settings that you do not
wish to enable. For example, specifying -e -w
0 will enable all settings except for LBP_W.
-l List available protection parmeters and their
current settings.
-L len Set the length of the protection information
in bytes. For Reed-Solomon CRC, the
protection information length should be 4
bytes.
-m num Specify the numeric value for the protection
method. The numeric value for Reed-Solomon
CRC is 1.
-r 0|1 Set the LBP_R parameter. When set, this
indicates that each block read from the tape
drive will have a checksum at the end.
-v Enable verbose mode for parameter listing.
This will include descriptions of each
parameter.
-w 0|1 Set the LBP_W parameter. When set, this
indicates that each block written to the tape
drive will have a checksum at the end. The
drive will verify the checksum before writing
the block to tape.
locate Set the tape drive's logical position. One of -b, -e,
-f, or -s must be specified to indicate the type of
position. If the partition number is specified, the
drive will first relocate to the given partition (if it
exists) and then to the position indicated within that
partition. If the partition number is not specified,
the drive will relocate to the given position within the
current partition.
-b block_addr Relocate to the given tape block or
logical object identifier. Note that
the block number is the Reported Record
Number that is relative to the beginning
of the partition (or beginning of tape).
-e Relocate to the end of data.
-f fileno Relocate to the given file number.
-p partition Specify the partition to change to.
-s setmark Relocate to the given set mark.
comp Set the drive's compression mode. The non-numeric
values of argument are:
off Turn compression off.
on Turn compression on.
none Same as off.
enable Same as on.
IDRC IBM Improved Data Recording Capability
compression (0x10).
DCLZ DCLZ compression algorithm (0x20).
In addition to the above recognized compression
keywords, the user can supply a numeric compression
algorithm for the drive to use. In most cases, simply
turning the compression `on' will have the desired
effect of enabling the default compression algorithm
supported by the drive. If this is not the case (see
the status display to see which compression algorithm is
currently in use), the user can manually specify one of
the supported compression keywords (above), or supply a
numeric compression value from the drive's
specifications.
Note that for some older tape drives (for example the
Exabyte 8200 and 8500 series drives) it is necessary to
switch to a different density to tell the drive to
record data in its compressed format. If the user
attempts to turn compression on while the uncompressed
density is selected, the drive will return an error.
This is generally not an issue for modern tape drives.
density Set the density for the drive. For the density codes,
see below. The density value could be given either
numerically, or as a string, corresponding to the
"Reference" field. If the string is abbreviated, it
will be resolved in the order shown in the table, and
the first matching entry will be used. If the given
string and the resulting canonical density name do not
match exactly, an informational message is output about
what the given string has been taken for.
The initial version of the density table below was taken from the
`Historical sequential access density codes' table (A-1) in Revision 11
of the SCSI-3 Stream Device Commands (SSC) working draft, dated November
11, 1997. Subsequent additions have come from a number of sources.
The density codes are:
0x0 default for device
0xE reserved for ECMA
Value Width Tracks Density Code Type Reference Note
mm in bpmm bpi
0x01 12.7 (0.5) 9 32 (800) NRZI R X3.22-1983 2
0x02 12.7 (0.5) 9 63 (1,600) PE R X3.39-1986 2
0x03 12.7 (0.5) 9 246 (6,250) GCR R X3.54-1986 2
0x05 6.3 (0.25) 4/9 315 (8,000) GCR C X3.136-1986 1,3
0x06 12.7 (0.5) 9 126 (3,200) PE R X3.157-1987 2
0x07 6.3 (0.25) 4 252 (6,400) IMFM C X3.116-1986 1
0x08 3.81 (0.15) 4 315 (8,000) GCR CS X3.158-1987 1
0x09 12.7 (0.5) 18 1,491 (37,871) GCR C X3.180 2
0x0A 12.7 (0.5) 22 262 (6,667) MFM C X3B5/86-199 1
0x0B 6.3 (0.25) 4 63 (1,600) PE C X3.56-1986 1
0x0C 12.7 (0.5) 24 500 (12,690) GCR C HI-TC1 1,6
0x0D 12.7 (0.5) 24 999 (25,380) GCR C HI-TC2 1,6
0x0F 6.3 (0.25) 15 394 (10,000) GCR C QIC-120 1,6
0x10 6.3 (0.25) 18 394 (10,000) GCR C QIC-150 1,6
0x11 6.3 (0.25) 26 630 (16,000) GCR C QIC-320 1,6
0x12 6.3 (0.25) 30 2,034 (51,667) RLL C QIC-1350 1,6
0x13 3.81 (0.15) 1 2,400 (61,000) DDS CS X3B5/88-185A 5
0x14 8.0 (0.315) 1 1,703 (43,245) RLL CS X3.202-1991 5,11
0x15 8.0 (0.315) 1 1,789 (45,434) RLL CS ECMA TC17 5,12
0x16 12.7 (0.5) 48 394 (10,000) MFM C X3.193-1990 1
0x17 12.7 (0.5) 48 1,673 (42,500) MFM C X3B5/91-174 1
0x18 12.7 (0.5) 112 1,673 (42,500) MFM C X3B5/92-50 1
0x19 12.7 (0.5) 128 2,460 (62,500) RLL C DLTapeIII 6,7
0x1A 12.7 (0.5) 128 3,214 (81,633) RLL C DLTapeIV(20) 6,7
0x1B 12.7 (0.5) 208 3,383 (85,937) RLL C DLTapeIV(35) 6,7
0x1C 6.3 (0.25) 34 1,654 (42,000) MFM C QIC-385M 1,6
0x1D 6.3 (0.25) 32 1,512 (38,400) GCR C QIC-410M 1,6
0x1E 6.3 (0.25) 30 1,385 (36,000) GCR C QIC-1000C 1,6
0x1F 6.3 (0.25) 30 2,666 (67,733) RLL C QIC-2100C 1,6
0x20 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-6GB(M) 1,6
0x21 6.3 (0.25) 144 2,666 (67,733) RLL C QIC-20GB(C) 1,6
0x22 6.3 (0.25) 42 1,600 (40,640) GCR C QIC-2GB(C) ?
0x23 6.3 (0.25) 38 2,666 (67,733) RLL C QIC-875M ?
0x24 3.81 (0.15) 1 2,400 (61,000) CS DDS-2 5
0x25 3.81 (0.15) 1 3,816 (97,000) CS DDS-3 5
0x26 3.81 (0.15) 1 3,816 (97,000) CS DDS-4 5
0x27 8.0 (0.315) 1 3,056 (77,611) RLL CS Mammoth 5
0x28 12.7 (0.5) 36 1,491 (37,871) GCR C X3.224 1
0x29 12.7 (0.5)
0x2A
0x2B 12.7 (0.5) 3 ? ? ? C X3.267 5
0x40 12.7 (0.5) 384 4,800 (123,952) C LTO-1
0x41 12.7 (0.5) 208 3,868 (98,250) RLL C DLTapeIV(40) 6,7
0x42 12.7 (0.5) 512 7,398 (187,909) C LTO-2
0x44 12.7 (0.5) 704 9,638 (244,805) C LTO-3
0x46 12.7 (0.5) 896 12,725 (323,215) C LTO-4
0x47 3.81 (0.25) ? 6,417 (163,000) CS DAT-72
0x48 12.7 (0.5) 448 5,236 (133,000) PRML C SDLTapeI(110) 6,8,13
0x49 12.7 (0.5) 448 7,598 (193,000) PRML C SDLTapeI(160) 6,8
0x4A 12.7 (0.5) 768 ? PRML C T10000A 10
0x4B 12.7 (0.5) 1152 ? PRML C T10000B 10
0x4C 12.7 (0.5) 3584 ? PRML C T10000C 10
0x4D 12.7 (0.5) 4608 ? PRML C T10000D 10
0x51 12.7 (0.5) 512 11,800 (299,720) C 3592A1 (unencrypted)
0x52 12.7 (0.5) 896 11,800 (299,720) C 3592A2 (unencrypted)
0x53 12.7 (0.5) 1152 13,452 (341,681) C 3592A3 (unencrypted)
0x54 12.7 (0.5) 2560 19,686 (500,024) C 3592A4 (unencrypted)
0x55 12.7 (0.5) 5120 20,670 (525,018) C 3592A5 (unencrypted)
0x56 12.7 (0.5) 7680 20,670 (525,018) C 3592B5 (unencrypted)
0x57 12.7 (0.5) 8704 21,850 (554,990) C 3592A6 (unencrypted)
0x58 12.7 (0.5) 1280 15,142 (384,607) C LTO-5
0x5A 12.7 (0.5) 2176 15,142 (384,607) C LTO-6
0x5C 12.7 (0.5) 3584 19,107 (485,318) C LTO-7
0x5D 12.7 (0.5) 5376 19,107 (485,318) C LTO-M8 14
0x5E 12.7 (0.5) 6656 20,669 (524,993) C LTO-8
0x60 12.7 (0.5) 8960 23,031 (584,987) C LTO-9
0x71 12.7 (0.5) 512 11,800 (299,720) C 3592A1 (encrypted)
0x72 12.7 (0.5) 896 11,800 (299,720) C 3592A2 (encrypted)
0x73 12.7 (0.5) 1152 13,452 (341,681) C 3592A3 (encrypted)
0x74 12.7 (0.5) 2560 19,686 (500,024) C 3592A4 (encrypted)
0x75 12.7 (0.5) 5120 20,670 (525,018) C 3592A5 (encrypted)
0x76 12.7 (0.5) 7680 20,670 (525,018) C 3592B5 (encrypted)
0x77 12.7 (0.5) 8704 21,850 (554,990) C 3592A6 (encrypted)
0x8c 8.0 (0.315) 1 1,789 (45,434) RLL CS EXB-8500c 5,9
0x90 8.0 (0.315) 1 1,703 (43,245) RLL CS EXB-8200c 5,9
Code Description Type Description
---- -------------------------------------- ---- -----------
NRZI Non return to zero, change on ones R Reel-to-reel
GCR Group code recording C Cartridge
PE Phase encoded CS Cassette
IMFM Inverted modified frequency modulation
MFM Modified frequency modulation
DDS DAT data storage
RLL Run length limited
PRML Partial Response Maximum Likelihood
NOTES
1. Serial recorded.
2. Parallel recorded.
3. Old format known as QIC-11.
5. Helical scan.
6. This is not an American National Standard. The reference is based
on an industry standard definition of the media format.
7. DLT recording: serially recorded track pairs (DLTapeIII and
DLTapeIV(20)), or track quads (DLTapeIV(35) and DLTapeIV(40)).
8. Super DLT (SDLT) recording: 56 serially recorded logical tracks
with 8 physical tracks each.
9. Vendor-specific Exabyte density code for compressed format.
10. bpi/bpmm values for the Oracle/StorageTek T10000 tape drives are
not listed in the manual. Someone with access to a drive can
supply the necessary values by running 'mt getdensity'.
11. This is Exabyte 8200 uncompressed format. The compressed format
density code is 0x90.
12. This is Exabyte 8500 uncompressed format. The compressed format
density code is 0x8c.
13. This density code (0x48) was also used for DAT-160.
14. Officially known as LTO-8 Type M, abbreviated M8. This is a pristine
LTO-7 cartridge initialized with a higher density format by an LTO-8
drive. It cannot be read by an LTO-7 drive. Uncompressed capacity
is 9TB, compared to 6TB for LTO-7 and 12TB for LTO-8.
NOTE ON QIC STREAMERS
The following is a table of Data Cartridge types as used in the 1/4 inch
tape drives such as the Archive Viper 150, Wangtek 5525ES, and Tandberg
TDC4220 tape drives:
Value Reference Format Cartridge Type Capacity Tracks Length
----- --------- ------ -------------- -------- ------ ------
0x05 QIC-11 DC300 15MB 4 300ft
0x05 QIC-11 DC300XL/P 20MB 4 450ft
0x05 QIC-11 DC600 27MB 4 600ft
0x05 X3.136-1986 QIC-24 DC615A 15MB 9 150ft
0x05 X3.136-1986 QIC-24 DC300XL/P 45MB 9 450ft
0x05 X3.136-1986 QIC-24 DC600A 60MB 9 600ft
0x0F QIC-120 QIC-120 DC600A/DC6150 120MB 15 620ft
0x10 QIC-150 QIC-150 DC600XTD/DC6150 150MB 18 620ft
0x10 QIC-150 QIC-150 DC6250 250MB 18 1,020ft
0x11 QIC-320 QIC-525 DC6320 320MB 26 620ft
0x11 QIC-320 QIC-525 DC6525 525MB 26 1,020ft
0x1E QIC-1000C QIC-1000 DC9100/DL9135 1.0GB 30 760ft
0x1E QIC-1000C QIC-1000 DC9150 1.2GB 30 950ft
0x22 QIC-2GB(C) QIC-2GB DC9200 2.0GB 42 950ft
0x22 QIC-2GB(C) QIC-2GB DC9250 2.5GB 42 1,200ft
Notes:
QIC-24, QIC-120, QIC-150 use fixed blocksize of 512 bytes, QIC-525,
QIC-1000 and QIC-2GB can use blocksize of 1,024 bytes. DDS (DAT) drives
generally use variable blocks.
QIC-02 and QIC-36 are interface standards for tape drives. The QIC-02
and QIC-36 streamers such as the Wangtek 5250EQ are otherwise identical
to their SCSI versions (i.e.: Wangtek 5250ES).
It seems that the 150MB and larger streamers cannot write QIC-24 9 track
formats, only read them.
DC600A cartridges marked "10,000ftpi" can only be used as QIC-11, QIC-24,
and QIC-120 format. DC600A cartridges marked 12,500ftpi can be used as
both QIC-120 and QIC-150 format.
Some manufacturers do not use "DC" on their cartridges. Verbatim uses
DL, Maxell uses MC, Sony uses QD, Quill uses DQ.
3M/Imation & Fuji use DC. Thus a DL6250, MC-6250, QD6250, DQ6250 are all
identical media to a DC6250.
QIC tape media is not "connected" to the take up reels and will de-spool
if the tape drive has dust covering the light sensor that looks for the
end of tape holes in the media.
ENVIRONMENT
TAPE This is the pathname of the tape drive. The default (if the
variable is unset, but not if it is null) is /dev/nsa0. It may
be overridden with the -f option.
FILES
/dev/*sa[0-9]* SCSI magnetic tape interface
DIAGNOSTICS
The exit status will be 0 when the drive operations were successful, 2
when the drive operations were unsuccessful, and 1 for other problems
like an unrecognized command or a missing drive device.
COMPATIBILITY
Some undocumented commands support old software.
SEE ALSO
dd(1), ioctl(2), mtio(4), sa(4), environ(7)
HISTORY
The mt command appeared in 4.3BSD.
Extensions regarding the st(4) driver appeared in 386BSD-0.1 as a
separate st command, and have been merged into the mt command in
FreeBSD 2.1.
The former eof command that used to be a synonym for weof has been
abandoned in FreeBSD 2.1 since it was often confused with eom, which is
fairly dangerous.
BUGS
The utility cannot be interrupted or killed during a long erase (which
can be longer than an hour), and it is easy to forget that the default
erase is long.
Hardware block numbers do not always correspond to blocks on the tape
when the drive uses internal compression.
Erasure is not guaranteed if the tape is not at its beginning.
Tape-related documentation is poor, here and elsewhere.
FreeBSD 13.1-RELEASE-p6 December 10, 2020 FreeBSD 13.1-RELEASE-p6
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