ST(4D) ST(4D)


st - driver for SCSI tape devices




The st device driver provides a standard interface to various SCSI tape
devices. See mtio(4I) for details.

To determine if the st device driver supports your tape device, SPARC
users should enter the following on a command line:

% strings /kernel/drv/sparcv9/st | grep -i <tape device name>

x86 users can do the following to determine if the st device driver
supports a particular tape device:

% strings /kernel/drv/st | grep -i <tape device name>

The driver can be opened with either rewind on close or no rewind on
close options. It can also be opened with the O_NDELAY (see open(2))
option when there is no tape inserted in the drive. A maximum of four
tape formats per device are supported (see FILES below). The tape format
is specified using the device name. (Tape format is also referred to as
tape density).

Following are a list of SCSI commands that can be executed while another
host reserves the tape drive. The commands are:


In multi-initiator environments, the driver will not reserve the tape
drive if above commands are issued. For other SCSI commands, the driver
reserves the tape drive and releases the drive at close if it has been
reserved. Refer to the MTIOCRESERVE and MTIOCRELEASE ioctls in mtio(4I)
for information about how to allow a tape drive to remain reserved upon
close. See the flag options below for information about disabling this

If a SCSI-3 persistent reservation is done through the driver, the
driver disables all existing SCSI-2 reservations.

If the tape drive is opened in O_NDELAY mode, no reservation occurs
during the open, as per the POSIX standard (see standards(7)). However,
if a command not found in the above list is used, a reservation will
occur to provide reserve/release functionality before the command is

Persistent Errors and Asynchronous Tape Operation

The st driver now supports persistent errors (see mtio(4I) and
asynchronous tape operations (see mtio(4I), aioread(3C), and

Read Operation

If the driver is opened for reading in a different format than the tape
is written in, the driver overrides the user-selected format. For
example, if a 1/4" cartridge tape is written in QIC-24 format and opened
for reading in QIC-150, the driver detects a read failure on the first
read and automatically switches to QIC-24 to read the data.

Note that if the low density format is used, no indication is given that
the driver has overridden the format you selected. Other formats issue a
warning message to inform you of an overridden format selection. Some
devices automatically perform this function and do not require driver
support (1/2" reel tape drive, for example).

Write Operation

Writing from the beginning of tape is performed in the user-specified
format. The original tape format is used for appending onto previously
written tapes.

Tape Configuration

The st driver has a built-in configuration table for most Sun-supported
tape drives. For those tape drives that are not in the table, the st
driver tries to read the configuration from the tape drive through
optional SCSI-3 commands. To support the addition of third party tape
devices which are not in the built-in configuration table or not able to
report their configuration, device information can be supplied in st.conf
as global properties that apply to each node, or as properties that are
applicable to one node only. By supplying the information in st.conf, the
built-in configuration is overridden and the st driver will not query the
configuration from tape drives. The st driver looks for the property
called tape-config-list. The value of this property is a list of
triplets, where each triplet consists of three strings.

The formal syntax is:

tape-config-list = <triplet> [, <triplet> *];


<triplet> := <vid+pid>, <pretty print>, <data-property-name>


<data-property-name> = <version>, <type>, <bsize>,
<options>, <number of densities>,
<density> [, <density>*], <default-density>;


<data-property-name> = <version 2>, <type>, <bsize>,
<options>, <number of densities>,
<density> [, <density>*], <default-density>,
<non-motion time-out>, <I/O time-out>,
<rewind time-out>, <space time-out>,
<load time-out>, <unload time-out>,
<erase time-out>;

A semicolon (;) is used to terminate a prototype devinfo node
specification. Individual elements listed within the specification should
not be separated by a semicolon. (Refer to driver.conf(5) for more

<vid+pid> is the string that is returned by the tape device on a SCSI
inquiry command. This string may contain any character in the range
0x20-0x7e. Characters such as " " " (double quote) or " ' " (single
quote), which are not permitted in property value strings, are
represented by their octal equivalent (for example, \042 and \047).
Trailing spaces may be truncated.

<pretty print> is used to report the device on the console. This string
may have zero length, in which case the <vid+pid> will be used to report
the device.

<data-property-name> is the name of the property which contains all the
tape configuration values (such as <type>, <bsize>, etc.) corresponding
for the tape drive for the specified <vid+pid>.

<version> is a version number and should be 1 or 2. In the future, higher
version numbers may be used to allow for changes in the syntax of the
<data-property-name> value list.

<type> is a type field. Valid types are defined in
/usr/include/sys/mtio.h. For third party tape configuration, the
following generic types are recommended:

MT_IS8MM 0x35
MT_ISSTK9840 0x39

<bsize> is the preferred block size of the tape device. The value should
be 0 for variable block size devices.

<options> is a bit pattern representing the devices, as defined in
/usr/include/sys/scsi/targets/stdef.h. Valid flags for tape configuration
are shown in the following table. Note that this table does not list
flags that are non-configurable in st.conf (including ST_KNOWS_MEDIA
which uses the media type reported from the mode select data to select
the correct density code).

ST_QIC 0x0002
ST_REEL 0x0004
ST_BSF 0x0008
ST_BSR 0x0010
ST_NOBUF 0x0080
ST_WORMABLE 0x1000000


The flag indicates the tape device supports variable length record


The flag indicates a Quarter Inch Cartridge (QIC) tape device.


The flag indicates a 1/2-inch reel tape device.


If flag is set, the device supports backspace over EOF marks (bsf -
see mt(1)).


If flag is set, the tape device supports the backspace record
operation (bsr - see mt(1)). If the device does not support bsr, the
st driver emulates the action by rewinding the tape and using the
forward space record (fsf) operation to forward the tape to the
correct file. The driver then uses forward space record (fsr - see
mt(1)) to forward the tape to the correct record.


The flag indicates the tape device needs a longer time than normal to


The auto-density override flag. The device is capable of determining
the tape density automatically without issuing a "mode-select"/"mode-
sense command."


The flag disables the device's ability to perform buffered writes. A
buffered write occurs when the device acknowledges the completion of
a write request after the data has been written to the device's
buffer, but before all of the data has been written to the tape.


If flag is set, the device can determine when EOD (End of Data) has
been reached. When this flag is set, the st driver uses fast file
skipping. Otherwise, file skipping happens one file at a time.


The flag indicates the device will not complain if the st driver is
unloaded and loaded again (see modload(8) and modunload(8)). That is,
the driver will return the correct inquiry string.


The flag indicates the tape device will perform a "request sense" or
"log sense" command when the device is closed. Currently, only
Exabyte and DAT drives support this feature.


The flag indicates the tape device requires timeouts that are five
times longer than usual for normal operation.


The flag applies to variable-length tape devices. If this flag is
set, the record size is not limited to a 64 Kbyte record size. The
record size is only limited by the smaller of either the record size
supported by the device or the maximum DMA transfer size of the
system. (Refer to Large Record Sizes and WARNINGS.) The maximum block
size that will not be broken into smaller blocks can be determined
from the mt_bf returned from the MTIOCGET ioctl(). This number is
the lesser of the upper block limit returned by the drive from READ
BLOCK LIMITS command and the dma-max property set by the Host Bus
Adapter (HBA) to which the drive is attached.


If the ST_MODE_SEL_COMP flag is set, the driver determines which of
the two mode pages the device supports for selecting or deselecting
compression. It first tries the Data Compression mode page (0x0F); if
this fails, it tries the Device Configuration mode page (0x10). Some
devices, however, may need a specific density code for selecting or
deselecting compression. Please refer to the device specific SCSI
manual. When the flag is set, compression is enabled only if the "c"
or "u" device is used. Note that when the lower 2 densities of a
drive are identically configured and the upper 2 densities are
identically configured, but the lower and upper differ from each
other and ST_MODE_SEL_COMP is set, the "m" node sets compression on
for the lower density code (for example, 0x42) and the "c" and "u"
nodes set compression on for the higher density (for example, 0x43).
For any other device densities, compression is disabled.


The ST_NO_RESERVE_RELEASE flag disables the use of reserve on open
and release on close. If an attempt to use a ioctl of MTRESERVE or
MTRELEASE on a drive with this flag set, it will return an error of
ENOTTY (inappropriate ioctl for device).


The ST_READ_IGNORE_ILI flag is applicable only to variable block
devices which support the SILI bit option. The ST_READ_IGNORE_ILI
flag indicates that SILI (suppress incorrect length indicator) bit
will be set during reads. When this flag is set, short reads
(requested read size is less than the record size on the tape) will
be successful and the number of bytes transferred will be equal to
the record size on the tape. The tape will be positioned at the start
of the next record skipping over the extra data (the remaining data
has been has been lost). Long reads (requested read size is more than
the record size on the tape) will see a large performance gain when
this flag is set, due to overhead reduction. When this flag is not
set, short reads will return an error of ENOMEM.


The ST_READ_IGNORE_EOFS flag is applicable only to 1/2" Reel Tape
drives and when performing consecutive reads only. It should not be
used for any other tape command. Usually End-of-recorded-media (EOM)
is indicated by two EOF marks on 1/2" tape and application cannot
read past EOM. When this flag is set, two EOF marks no longer
indicate EOM allowing applications to read past two EOF marks. In
this case it is the responsibility of the application to detect end-
of-recorded-media (EOM). When this flag is set, tape operations (like
MTEOM) which positions the tape at end-of-recorded-media will fail
since detection of end-of-recorded-media (EOM) is to be handled by
the application. This flag should be used when backup applications
have embedded double filemarks between files.


The ST_SHORT_FILEMARKS flag is applicable only to EXABYTE 8mm tape
drives which supports short filemarks. When this flag is set, short
filemarks is used for writing filemarks. Short filemarks could lead
to tape incompatible with some otherwise compatible device. By
default long filemarks will be used for writing filemarks.


If ST_EJECT_TAPE_ON_CHANGER_FAILURE flag is set, the tape is ejected
automatically if the tape cartridge is trapped in the medium due to
positioning problems of the medium changer.

The following ASC/ASCQ keys are defined to the reasons for causing
tape ejection if ST_EJECT_TAPE_ON_CHANGER_FAILURE option is set to

Sense ASC/ASCQ Description


4 15/01 Mechanical Failure

4 44/00 Internal Target Failure

2 53/00 Media Load or Eject Failed

4 53/00 Media Load or Eject Failed

4 53/01 Unload Tape Failure


If ST_RETRY_ON_RECOVERED_DEFERRED_ERROR flag is set, the st driver
will retry the last write if this cmd caused a check condition with
error code 0x71 and sense code 0x01. Some tape drives, notably the
IBM 3090, require this option.


When ST_WORMABLE is set, st attempts to detect the presence of WORM
media in the device.

<number of densities> is the number of densities specified. Each tape
drive can support up to four densities. The value entered should
therefore be between 1 and 4; if less than 4, the remaining densities
will be assigned a value of 0x0.

<density> is a single-byte hexadecimal number. It can either be found in
the device specification manual or be obtained from the device vendor.

<default-density> has a value between 0 and (<number of densities> - 1).

<non-motion time-out> Time in seconds that the drive should be able to
perform any SCSI command that doesn't require tape to be moved. This
includes mode sense, mode select, reserve, release, read block limits,
and test unit ready.

<I/O time-out> Time in seconds to perform data transfer I/O to or from
tape including worst case error recovery.

<rewind time-out> Time in seconds to rewind from anywhere on tape to BOT
including worst case recovery forcing buffered write data to tape.

<space time-out> Time in seconds to space to any file, block or end of
data on tape. Including worst case when any form of cataloging is

<load time-out> Time in seconds to load tape and be ready to transfer
first block. This should include worst case recovery reading tape catalog
or drive specific operations done at load.

<unload time-out> Time in seconds to unload tape. Should include worst
case time to write to catalog, unthread, and tape cartridge unloading.
Also should include worst case time for any drive specific operations
that are preformed at unload. Should not include rewind time as the
driver rewinds tape before issuing the unload.

<erase time-out> Time in seconds to preform a full (BOT to EOT) erase of
longest medium with worst case error recovery.

Device Statistics Support

Each device maintains I/O statistics both for the device and for each
partition allocated on that device. For each device/partition, the driver
accumulates reads, writes, bytes read, and bytes written. The driver also
takes hi-resolution time stamps at queue entry and exit points, which
facilitates monitoring the residence time and cumulative residence-length
product for each queue.

Each device also has error statistics associated with it. These must
include counters for hard errors, soft errors and transport errors. Other
data may be implemented as required.


The behavior of SCSI tape positioning ioctls is the same across all
devices which support them. (Refer to mtio(4I).) However, not all devices
support all ioctls. The driver returns an ENOTTY error on unsupported

The retension ioctl only applies to 1/4" cartridge tape devices. It is
used to restore tape tension, thus improving the tape's soft error rate
after extensive start-stop operations or long-term storage.

In order to increase performance of variable-length tape devices
(particularly when they are used to read/write small record sizes), two
operations in the MTIOCTOP ioctl, MTSRSZ and MTGRSZ, can be used to set
and get fixed record lengths. The ioctl also works with fixed-length tape
drives which allow multiple record sizes. The min/max limits of record
size allowed on a driver are found by using a SCSI-2 READ BLOCK LIMITS
command to the device. If this command fails, the default min/max record
sizes allowed are 1 byte and 63k bytes. An application that needs to use
a different record size opens the device, sets the size with the MTSRSZ
ioctl, and then continues with I/O. The scope of the change in record
size remains until the device is closed. The next open to the device
resets the record size to the default record size (retrieved from

Note that the error status is reset by the MTIOCGET get status ioctl call
or by the next read, write, or other ioctl operation. If no error has
occurred (sense key is 0), the current file and record position is


The driver is opened for write access and the tape is write-
protected or the tape unit is reserved by another host.

The tape drive is in use by another process. Only one process
can use the tape drive at a time. The driver will allow a grace
period for the other process to finish before reporting this

The number of bytes read or written is not a multiple of the
physical record size (fixed-length tape devices only).

During opening, the tape device is not ready because either no
tape is in the drive, or the drive is not on-line. Once open,
this error is returned if the requested I/O transfer could not
be completed.

This indicates that the tape device does not support the
requested ioctl function.

During opening, the tape device does not exist.

This indicates that the record size on the tape drive is more
than the requested size during read operation.


Example 1: Global tape-config list property

The following is an example of a global tape-config-list property:

tape-config-list =
"Magic DAT", "Magic 4mm Helical Scan", "magic-data",
"Major Appliance", "Major Appliance Tape", "major-tape";

magic-data = 1,0x34,1024,0x1639,4,0,0x8c,0x8c,0x8c,3;
major-tape = 2,0x3c,0,0x18619,4,0x0,0x0,0x0,0x0,

name="st" class="scsi"
target=0 lun=0;
name="st" class="scsi"
target=1 lun=0;
name="st" class="scsi"
target=2 lun=0;
name="st" class="scsi"
target=6 lun=0;

Example 2: Tape-config-list property applicable to target 2 only

The following is an example of a tape-config-list property applicable to
target 2 only:

name="st" class="scsi"
target=0 lun=0;
name="st" class="scsi"
target=1 lun=0;
name="st" class="scsi"
target=2 lun=0
tape-config-list =
"Magic DAT", "Magic 4mm Helical Scan", "magic-data"
magic-data = 1,0x34,1024,0x1639,4,0,0x8c,0x8c,0x8c,3;
name="st" class="scsi"
target=3 lun=0;
name="st" class="scsi"
target=6 lun=0;

Large Record Sizes

To support applications such as seismic programs that require large
record sizes, the flag ST_NO_RECSIZE_LIMIT must be set in drive option in
the configuration entry. A SCSI tape drive that needs to transfer large
records should OR this flag with other flags in the 'options' field in
st.conf. (Refer to Tape Configuration.) By default, this flag is set for
the built-in config entries of Archive DAT and Exabyte drives.

If this flag is set, the st driver issues a SCSI-2 READ BLOCK LIMITS
command to the device to determine the maximum record size allowed by it.
If the command fails, st continues to use the maximum record sizes
mentioned in the mtio(4I) man page.

If the command succeeds, st restricts the maximum transfer size of a
variable-length device to the minimum of that record size and the maximum
DMA size that the host adapter can handle. Fixed-length devices are bound
by the maximum DMA size allocated by the machine. Note that tapes created
with a large record size may not be readable by earlier releases or on
other platforms.

(Refer to the WARNINGS section for more information.)

EOT Handling

The Emulex drives have only a physical end of tape (PEOT); thus it is not
possible to write past EOT. All other drives have a logical end of tape
(LEOT) before PEOT to guarantee flushing the data onto the tape. The
amount of storage between LEOT and PEOT varies from less than 1 Mbyte to
about 20 Mbyte, depending on the tape drive.

If EOT is encountered while writing an Emulex, no error is reported but
the number of bytes transferred is 0 and no further writing is allowed.
On all other drives, the first write that encounters EOT will return a
short count or 0. If a short count is returned, then the next write will
return 0. After a zero count is returned, the next write returns a full
count or short count. A following write returns 0 again. It is important
that the number and size of trailer records be kept as small as possible
to prevent data loss. Therefore, writing after EOT is not recommended.

Reading past EOT is transparent to the user. Reading is stopped only by
reading EOF's. For 1/2" reel devices, it is possible to read off the end
of the reel if one reads past the two file marks which mark the end of
recorded media.



driver configuration file


structures and definitions for mag tape io control commands


definitions for SCSI tape drives

/dev/rmt/[0- 127][l,m,h,u,c][b][n]

where l,m,h,u,c specifies the density (low, medium, high,
ultra/compressed), b the optional BSD behavior (see mtio(4I)), and n
the optional no rewind behavior. For example, /dev/rmt/0lbn specifies
unit 0, low density, BSD behavior, and no rewind.

For 1/2" reel tape devices (HP-88780), the densities are:

l 800 BPI density
m 1600 BPI density
h 6250 BPI density
c data compression
(not supported on all modules)

For 8mm tape devices (Exabyte 8200/8500/8505):

l Standard 2 Gbyte format
m 5 Gbyte format (8500, 8505 only)
h,c 5 Gbyte compressed format (8505 only)

For 4mm DAT tape devices (Archive Python):

l Standard format
m,h,c data compression

For all QIC (other than QIC-24) tape devices:

l,m,h,c density of the tape cartridge type
(not all devices can read and
write all formats)

For QIC-24 tape devices (Emulex MT-02):

l QIC-11 Format
m,h,c QIC-24 Format


mt(1), open(2), read(2), write(2), aioread(3C), aiowrite(3C),
kstat(3KSTAT), esp(4D), isp(4D), mtio(4I), driver.conf(5), scsi(5),
standards(7), modload(8), modunload(8), ioctl(9E)


The st driver diagnostics may be printed to the console or messages file.

Each diagnostic is dependent on the value of the system variable
st_error_level. st_error_level may be set in the /etc/system file. The
default setting for st_error_level is 4 (SCSI_ERR_RETRYABLE) which is
suitable for most configurations since only actual fault diagnostics are
printed. Settings range from values 0 (SCSI_ERR_ALL) which is most
verbose, to 6 (SCSI_ERR_NONE) which is least verbose. See stdef.h for the
full list of error-levels. SCSI_ERR_ALL level the amount of diagnostic
information is likely to be excessive and unnecessary.

The st driver diagnostics are described below:

Error for Command: <scsi_cmd_name()> Error Level:<error_class>
Requested Block: <blkno> Error Block: <err_blkno>
Vendor: <name>: Serial Number: <inq_serial>
Sense Key: <es_key> ASC: 0x<es_add_code> (scsi_asc_ascq_name()>), ASCQ:
0x<es_qual_code>, FRU: 0x<ex_fru_code>

where <error_class> may be any one of the following: "All," "Unknown,"
"Informational," "Recovered," "Retryable," "Fatal"

The command indicated by <scsi_cmd_name> failed. Requested Block
represents the block where the transfer started. Error Block represents
the block that caused the error. Sense Key, ASC, ASCQ and FRU information
is returned by the target in response to a request sense command. See
SCSI protocol documentation for description of Sense Key, ASC, ASCQ, FRU.

The st driver attempts to validate entries in the st.conf file. Each
field in the entry is checked for upper and lower limits and invalid bits
set. The fields are named as follows in config string order:

conf version
drive type
block size
number of densities
density code
default density
non motion timeout
I/O timeout
space timeout
load timeout
unload timeout
erase timeout

The st.conf diagnostics are described below:

<con-name> <field-in-err> <problem-with-field>

where <con-name> is the name of the config string. Where <field-in-err>
is the field containing invalid entries and where <problem-with-field>
describes the nature of the invalid entry.

Write/read: not modulo <n> block size

The request size for fixed record size devices must be a multiple of the
specified block size.

Recovery by resets failed

After a transport error, the driver attempted to recover by issuing a
device reset and then a bus reset if device reset failed. These
recoveries failed.

Periodic head cleaning required

The driver reported that periodic head cleaning is now required. This
diagnostic is generated either due to a threshold number of retries, or
due to the device communicating to the driver that head cleaning is

Soft error rate (<n>%) during writing/reading was too high

The soft error rate has exceeded the threshold specified by the vendor.

SCSI transport failed: reason 'xxxx': {retrying|giving up}

The Host Bus Adapter (HBA) has failed to transport a command to the
target for the reason stated. The driver will either retry the command
or, ultimately, give up.

Tape not inserted in drive

A media access command was attempted while there was no tape inserted
into the specified drive. In this case, the drive returns sense key of

Transport rejected

The Host Bus Adapter (HBA) driver is not accepting commands after failing
to successfully transport a scsi packet to the target. The actual status
received by the st driver from the underlying HBA driver was either

Retrying command

The st driver failed to complete a command. However the command is
retryable and will be retried.

Giving up

The st driver has exhausted retries or otherwise is unable to retry the
command and so is giving up.

No target struct for st%d

The st driver failed to obtain state information because the requested
state structure was not allocated. The specified device was probably not

File mark detected

The operation detected an end of file mark. (File marks signify the end
of a file on the tape media).

End-of-media detected

The operation reached the end of the tape media.

Exabyte soft error reporting failed. DAT soft error reporting failed

The st driver was unable to determine if the soft error threshold had
been exceeded because it did not successfully read the data it requires
or did not obtain enough data. This data is retrieved using the log sense

Log sense parameter code does not make sense

The log sense command retrieves hardware statistics that are stored on
the drive (for example, soft error counts and retries.) If the data
retrieved from the drive is invalid, this message is printed and the data
is not used.

Restoring tape position at fileno=%x, blkno=%lx....

The st driver is positioning to the specified file and block. This occurs
on an open.

Failed to restore the last <file/block> position:
In this state, tape will be loaded at BOT during next open

The st driver could not position to the specified location and will
revert to the beginning of the tape when the next open is attempted.

Device does not support compression

The compression facility of the device was requested. However the device
does not have a hardware compression capability.

DAT soft error reset failed

After DAT soft error reporting, the counters within the device that
accumulate this sense data need to be re-set. This operation failed.

Errors after pkt alloc (b_flags=0x%x, b_error=0x%x)

Memory allocation for a scsi packet failed.

Incorrect length indicator set

The drive reported the length of data requested in a READ operation, was
incorrect. Incorrect Length Indicator (ILI) is a very commonly used
facility in SCSI tape protocol and should not be seen as an error per-se.
Applications typically probe a new tape with a read of any length, using
the returned length to the read system call for future reads. Along with
this operation, an underlying ILI error is received. ILI errors are
therefore informational only and are masked at the default

Data property (%s) has no value
Data property (%s) incomplete
Version # for data property (%s) greater than 1

These diagnostics indicate problems in retrieving the values of the
various property settings. The st driver is in the process of setting the
property/parameter values for the tape drive using information from
either the built-in table within the driver or from uncommented entries
in the st.conf file. The effect on the system may be that the tape drive
may be set with default or generic driver settings which may not be
appropriate for the actual type of tape drive being used.

st_attach-RESUME: tape failure tape position will be lost

On a resume after a power management suspend, the previously known tape
position is no longer valid. This can occur if the tape was changed while
the system was in power management suspend. The operation will not be

Write Data Buffering has been deprecated. Your applications should
continue to work normally. However, they should be ported to use
Asynchronous I/O.

Indicates that buffering has been removed from Solaris.

Cannot detach: fileno=%x, blkno=%lx

The st driver cannot unload because the tape is not positioned at BOT
(beginning of tape). May indicate hardware problems with the tape drive.

Variable record length I/O
Fixed record length (%d byte blocks) I/O

Tape-drives can use either Fixed or Variable record length. If the drive
uses Fixed length records, then the built in property table or the
st.conf file will contain a non-zero record-length property. Most DAT,
Exabyte and DLT drives support Variable record lengths. Many QIC format
tape drives have historically been of Fixed record length.

Command will be retried
un_ncmds: %d can't retry cmd

These diagnostics are only seen with tape drives with the
ST_RETRY_ON_RECOVERED_DEFERRED_ERROR bit set. See stdef.h for explanation
of the specific usage of this setting.


Effective with Solaris 2.4, the ST_NO_RECSIZE_LIMIT flag is set for the
built-in config entries of the Archive DAT and Exabyte drivers by
default. (Refer to Large Record Sizes.) Tapes written with large block
sizes prior to Solaris 2.4 may cause some applications to fail if the
number of bytes returned by a read request is less than the requested
block size (for example, asking for 128 Kbytes and receiving less than 64

The ST_NO_RECSIZE_LIMIT flag can be disabled in the config entry for the
device as a work-around. (Refer to Tape Configuration.) This action
disables the ability to read and write with large block sizes and allows
the reading of tapes written prior to Solaris 2.4 with large block sizes.

(Refer to mtio(4I) for a description of maximum record sizes.)


Tape devices that do not return a BUSY status during tape loading prevent
user commands from being held until the device is ready. The user must
delay issuing any tape operations until the tape device is ready. This is
not a problem for tape devices supplied by Sun Microsystems.

Tape devices that do not report a blank check error at the end of
recorded media may cause file positioning operations to fail. Some tape
drives, for example, mistakenly report media error instead of blank check

April 9, 2016 ST(4D)