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diff --git a/man4/st.4 b/man4/st.4 deleted file mode 100644 index ebdbf0407..000000000 --- a/man4/st.4 +++ /dev/null @@ -1,950 +0,0 @@ -.\" Copyright 1995 Robert K. Nichols (Robert.K.Nichols@att.com) -.\" Copyright 1999-2005 Kai Mäkisara (Kai.Makisara@kolumbus.fi) -.\" -.\" SPDX-License-Identifier: Linux-man-pages-copyleft -.TH st 4 (date) "Linux man-pages (unreleased)" -.SH NAME -st \- SCSI tape device -.SH SYNOPSIS -.nf -.B #include <sys/mtio.h> -.PP -.BI "int ioctl(int " fd ", int " request " [, (void *)" arg3 "]);" -.BI "int ioctl(int " fd ", MTIOCTOP, (struct mtop *)" mt_cmd ); -.BI "int ioctl(int " fd ", MTIOCGET, (struct mtget *)" mt_status ); -.BI "int ioctl(int " fd ", MTIOCPOS, (struct mtpos *)" mt_pos ); -.fi -.SH DESCRIPTION -The -.B st -driver provides the interface to a variety of SCSI tape devices. -Currently, the driver takes control of all detected devices of type -\[lq]sequential-access\[rq]. -The -.B st -driver uses major device number 9. -.PP -Each device uses eight minor device numbers. -The lowermost five bits -in the minor numbers are assigned sequentially in the order of -detection. -In the 2.6 kernel, the bits above the eight lowermost bits are -concatenated to the five lowermost bits to form the tape number. -The minor numbers can be grouped into -two sets of four numbers: the principal (auto-rewind) minor device numbers, -.IR n , -and the \[lq]no-rewind\[rq] device numbers, -.RI ( n " + 128)." -Devices opened using the principal device number will be sent a -.B REWIND -command when they are closed. -Devices opened using the \[lq]no-rewind\[rq] device number will not. -(Note that using an auto-rewind device for positioning the tape with, -for instance, mt does not lead to the desired result: the tape is -rewound after the mt command and the next command starts from the -beginning of the tape). -.PP -Within each group, four minor numbers are available to define -devices with different characteristics (block size, compression, -density, etc.) -When the system starts up, only the first device is available. -The other three are activated when the default -characteristics are defined (see below). -(By changing compile-time -constants, it is possible to change the balance between the maximum -number of tape drives and the number of minor numbers for each -drive. -The default allocation allows control of 32 tape drives. -For instance, it is possible to control up to 64 tape drives -with two minor numbers for different options.) -.PP -Devices are typically created by: -.PP -.in +4n -.EX -mknod \-m 666 /dev/st0 c 9 0 -mknod \-m 666 /dev/st0l c 9 32 -mknod \-m 666 /dev/st0m c 9 64 -mknod \-m 666 /dev/st0a c 9 96 -mknod \-m 666 /dev/nst0 c 9 128 -mknod \-m 666 /dev/nst0l c 9 160 -mknod \-m 666 /dev/nst0m c 9 192 -mknod \-m 666 /dev/nst0a c 9 224 -.EE -.in -.PP -There is no corresponding block device. -.PP -The driver uses an internal buffer that has to be large enough to hold -at least one tape block. -Before Linux 2.1.121, the buffer is -allocated as one contiguous block. -This limits the block size to the -largest contiguous block of memory the kernel allocator can provide. -The limit is currently 128\ kB for 32-bit architectures and -256\ kB for 64-bit architectures. -In newer kernels the driver -allocates the buffer in several parts if necessary. -By default, the -maximum number of parts is 16. -This means that the maximum block size -is very large (2\ MB if allocation of 16 blocks of 128\ kB succeeds). -.PP -The driver's internal buffer size is determined by a compile-time -constant which can be overridden with a kernel startup option. -In addition to this, the driver tries to allocate a larger temporary -buffer at run time if necessary. -However, run-time allocation of large -contiguous blocks of memory may fail and it is advisable not to rely -too much on dynamic buffer allocation before Linux 2.1.121 -(this applies also to demand-loading the driver with kerneld or kmod). -.PP -The driver does not specifically support any tape drive brand or -model. -After system start-up the tape device options are defined by -the drive firmware. -For example, if the drive firmware selects fixed-block mode, -the tape device uses fixed-block mode. -The options can -be changed with explicit -.BR ioctl (2) -calls and remain in effect when the device is closed and reopened. -Setting the options affects both the auto-rewind and the nonrewind -device. -.PP -Different options can be specified for the different devices within -the subgroup of four. -The options take effect when the device is -opened. -For example, the system administrator can define -one device that writes in fixed-block mode with a certain block size, -and one which writes in variable-block mode (if the drive supports -both modes). -.PP -The driver supports -.B tape partitions -if they are supported by the drive. -(Note that the tape partitions -have nothing to do with disk partitions. -A partitioned tape can be -seen as several logical tapes within one medium.) -Partition support has to be enabled with an -.BR ioctl (2). -The tape -location is preserved within each partition across partition changes. -The partition used for subsequent tape operations is -selected with an -.BR ioctl (2). -The partition switch is executed together with -the next tape operation in order to avoid unnecessary tape -movement. -The maximum number of partitions on a tape is defined by a -compile-time constant (originally four). -The driver contains an -.BR ioctl (2) -that can format a tape with either one or two partitions. -.PP -Device -.I /dev/tape -is usually created as a hard or soft link to the default tape device -on the system. -.PP -Starting from Linux 2.6.2, the driver exports in the sysfs directory -.I /sys/class/scsi_tape -the attached devices and some parameters assigned to the devices. -.SS Data transfer -The driver supports operation in both fixed-block mode and -variable-block mode (if supported by the drive). -In fixed-block mode the drive -writes blocks of the specified size and the block size is not -dependent on the byte counts of the write system calls. -In variable-block mode one tape block is written for each write call -and the byte -count determines the size of the corresponding tape block. -Note that -the blocks on the tape don't contain any information about the -writing mode: when reading, the only important thing is to use -commands that accept the block sizes on the tape. -.PP -In variable-block mode the read byte count does not have to match -the tape block size exactly. -If the byte count is larger than the -next block on tape, the driver returns the data and the function -returns the actual block size. -If the block size is larger than the -byte count, an error is returned. -.PP -In fixed-block mode the read byte counts can be arbitrary if -buffering is enabled, or a multiple of the tape block size if -buffering is disabled. -Before Linux 2.1.121 allow writes with -arbitrary byte count if buffering is enabled. -In all other cases -(before Linux 2.1.121 with buffering disabled or newer kernel) the -write byte count must be a multiple of the tape block size. -.PP -In Linux 2.6, the driver tries to use direct transfers between the user -buffer and the device. -If this is not possible, the driver's internal buffer -is used. -The reasons for not using direct transfers include improper alignment -of the user buffer (default is 512 bytes but this can be changed by the HBA -driver), one or more pages of the user buffer not reachable by the -SCSI adapter, and so on. -.PP -A filemark is automatically written to tape if the last tape operation -before close was a write. -.PP -When a filemark is encountered while reading, the following -happens. -If there are data remaining in the buffer when the filemark -is found, the buffered data is returned. -The next read returns zero -bytes. -The following read returns data from the next file. -The end of -recorded data is signaled by returning zero bytes for two consecutive -read calls. -The third read returns an error. -.SS Ioctls -The driver supports three -.BR ioctl (2) -requests. -Requests not recognized by the -.B st -driver are passed to the -.B SCSI -driver. -The definitions below are from -.IR /usr/include/linux/mtio.h : -.SS MTIOCTOP \[em] perform a tape operation -This request takes an argument of type -.IR "(struct mtop\ *)" . -Not all drives support all operations. -The driver returns an -.B EIO -error if the drive rejects an operation. -.PP -.in +4n -.EX -/* Structure for MTIOCTOP \- mag tape op command: */ -struct mtop { - short mt_op; /* operations defined below */ - int mt_count; /* how many of them */ -}; -.EE -.in -.PP -Magnetic tape operations for normal tape use: -.TP -.B MTBSF -Backward space over -.I mt_count -filemarks. -.TP -.B MTBSFM -Backward space over -.I mt_count -filemarks. -Reposition the tape to the EOT side of the last filemark. -.TP -.B MTBSR -Backward space over -.I mt_count -records (tape blocks). -.TP -.B MTBSS -Backward space over -.I mt_count -setmarks. -.TP -.B MTCOMPRESSION -Enable compression of tape data within the drive if -.I mt_count -is nonzero and disable compression if -.I mt_count -is zero. -This command uses the MODE page 15 supported by most DATs. -.TP -.B MTEOM -Go to the end of the recorded media (for appending files). -.TP -.B MTERASE -Erase tape. -With Linux 2.6, short erase (mark tape empty) is performed if the -argument is zero. -Otherwise, long erase (erase all) is done. -.TP -.B MTFSF -Forward space over -.I mt_count -filemarks. -.TP -.B MTFSFM -Forward space over -.I mt_count -filemarks. -Reposition the tape to the BOT side of the last filemark. -.TP -.B MTFSR -Forward space over -.I mt_count -records (tape blocks). -.TP -.B MTFSS -Forward space over -.I mt_count -setmarks. -.TP -.B MTLOAD -Execute the SCSI load command. -A special case is available for some HP -autoloaders. -If -.I mt_count -is the constant -.B MT_ST_HPLOADER_OFFSET -plus a number, the number is -sent to the drive to control the autoloader. -.TP -.B MTLOCK -Lock the tape drive door. -.TP -.B MTMKPART -Format the tape into one or two partitions. -If -.I mt_count -is positive, it gives the size of partition 1 and partition -0 contains the rest of the tape. -If -.I mt_count -is zero, the tape is formatted into one partition. -From Linux 4.6, -.\" commit 8038e6456a3e6f5c4759e0d73c4f9165b90c93e7 -a negative -.I mt_count -specifies the size of partition 0 and -the rest of the tape contains partition 1. -The physical ordering of partitions depends on the drive. -This command is not allowed for a drive unless the partition support -is enabled for the drive (see -.B MT_ST_CAN_PARTITIONS -below). -.TP -.B MTNOP -No op\[em]flushes the driver's buffer as a side effect. -Should be used before reading status with -.BR MTIOCGET . -.TP -.B MTOFFL -Rewind and put the drive off line. -.TP -.B MTRESET -Reset drive. -.TP -.B MTRETEN -Re-tension tape. -.TP -.B MTREW -Rewind. -.TP -.B MTSEEK -Seek to the tape block number specified in -.IR mt_count . -This operation requires either a SCSI-2 drive that supports the -.B LOCATE -command (device-specific address) -or a Tandberg-compatible SCSI-1 drive (Tandberg, Archive -Viper, Wangtek, ...). -The block number should be one that was previously returned by -.B MTIOCPOS -if device-specific addresses are used. -.TP -.B MTSETBLK -Set the drive's block length to the value specified in -.IR mt_count . -A block length of zero sets the drive to variable block size mode. -.TP -.B MTSETDENSITY -Set the tape density to the code in -.IR mt_count . -The density codes supported by a drive can be found from the drive -documentation. -.TP -.B MTSETPART -The active partition is switched to -.IR mt_count . -The partitions are numbered from zero. -This command is not allowed for -a drive unless the partition support is enabled for the drive (see -.B MT_ST_CAN_PARTITIONS -below). -.TP -.B MTUNLOAD -Execute the SCSI unload command (does not eject the tape). -.TP -.B MTUNLOCK -Unlock the tape drive door. -.TP -.B MTWEOF -Write -.I mt_count -filemarks. -.TP -.B MTWSM -Write -.I mt_count -setmarks. -.PP -Magnetic tape operations for setting of device options (by the superuser): -.TP -.B MTSETDRVBUFFER -Set various drive and driver options according to bits encoded in -.IR mt_count . -These consist of the drive's buffering mode, a set of Boolean driver -options, the buffer write threshold, defaults for the block size and -density, and timeouts (only since Linux 2.1). -A single operation can affect only one item in the list below (the -Booleans counted as one item.) -.IP -A value having zeros in the high-order 4 bits will be used to set the -drive's buffering mode. -The buffering modes are: -.RS -.TP -.B 0 -The drive will not report -.B GOOD -status on write commands until the data -blocks are actually written to the medium. -.TP -.B 1 -The drive may report -.B GOOD -status on write commands as soon as all the -data has been transferred to the drive's internal buffer. -.TP -.B 2 -The drive may report -.B GOOD -status on write commands as soon as (a) all -the data has been transferred to the drive's internal buffer, and -(b) all buffered data from different initiators has been successfully -written to the medium. -.RE -.IP -To control the write threshold the value in -.I mt_count -must include the constant -.B MT_ST_WRITE_THRESHOLD -bitwise ORed with a block count in the low 28 bits. -The block count refers to 1024-byte blocks, not the physical block -size on the tape. -The threshold cannot exceed the driver's internal buffer size (see -DESCRIPTION, above). -.IP -To set and clear the Boolean options -the value in -.I mt_count -must include one of the constants -.BR MT_ST_BOOLEANS , -.BR MT_ST_SETBOOLEANS , -.BR MT_ST_CLEARBOOLEANS , -or -.B MT_ST_DEFBOOLEANS -bitwise ORed with -whatever combination of the following options is desired. -Using -.B MT_ST_BOOLEANS -the options can be set to the values -defined in the corresponding bits. -With -.B MT_ST_SETBOOLEANS -the options can be selectively set and with -.B MT_ST_DEFBOOLEANS -selectively cleared. -.IP -The default options for a tape device are set with -.BR MT_ST_DEFBOOLEANS . -A nonactive tape device (e.g., device with -minor 32 or 160) is activated when the default options for it are -defined the first time. -An activated device inherits from the device -activated at start-up the options not set explicitly. -.IP -The Boolean options are: -.RS -.TP -.BR MT_ST_BUFFER_WRITES " (Default: true)" -Buffer all write operations in fixed-block mode. -If this option is false and the drive uses a fixed block size, then -all write operations must be for a multiple of the block size. -This option must be set false to write reliable multivolume archives. -.TP -.BR MT_ST_ASYNC_WRITES " (Default: true)" -When this option is true, write operations return immediately without -waiting for the data to be transferred to the drive if the data fits -into the driver's buffer. -The write threshold determines how full the buffer must be before a -new SCSI write command is issued. -Any errors reported by the drive will be held until the next -operation. -This option must be set false to write reliable multivolume archives. -.TP -.BR MT_ST_READ_AHEAD " (Default: true)" -This option causes the driver to provide read buffering and -read-ahead in fixed-block mode. -If this option is false and the drive uses a fixed block size, then -all read operations must be for a multiple of the block size. -.TP -.BR MT_ST_TWO_FM " (Default: false)" -This option modifies the driver behavior when a file is closed. -The normal action is to write a single filemark. -If the option is true, the driver will write two filemarks and -backspace over the second one. -.IP -Note: -This option should not be set true for QIC tape drives since they are -unable to overwrite a filemark. -These drives detect the end of recorded data by testing for blank tape -rather than two consecutive filemarks. -Most other current drives also -detect the end of recorded data and using two filemarks is usually -necessary only when interchanging tapes with some other systems. -.TP -.BR MT_ST_DEBUGGING " (Default: false)" -This option turns on various debugging messages from the driver -(effective only if the driver was compiled with -.B DEBUG -defined nonzero). -.TP -.BR MT_ST_FAST_EOM " (Default: false)" -This option causes the -.B MTEOM -operation to be sent directly to the -drive, potentially speeding up the operation but causing the driver to -lose track of the current file number normally returned by the -.B MTIOCGET -request. -If -.B MT_ST_FAST_EOM -is false, the driver will respond to an -.B MTEOM -request by forward spacing over files. -.TP -.BR MT_ST_AUTO_LOCK " (Default: false)" -When this option is true, the drive door is locked when the device file is -opened and unlocked when it is closed. -.TP -.BR MT_ST_DEF_WRITES " (Default: false)" -The tape options (block size, mode, compression, etc.) may change -when changing from one device linked to a drive to another device -linked to the same drive depending on how the devices are -defined. -This option defines when the changes are enforced by the -driver using SCSI-commands and when the drives auto-detection -capabilities are relied upon. -If this option is false, the driver -sends the SCSI-commands immediately when the device is changed. -If the -option is true, the SCSI-commands are not sent until a write is -requested. -In this case, the drive firmware is allowed to detect the -tape structure when reading and the SCSI-commands are used only to -make sure that a tape is written according to the correct specification. -.TP -.BR MT_ST_CAN_BSR " (Default: false)" -When read-ahead is used, the tape must sometimes be spaced backward to the -correct position when the device is closed and the SCSI command to -space backward over records is used for this purpose. -Some older -drives can't process this command reliably and this option can be used -to instruct the driver not to use the command. -The end result is that, -with read-ahead and fixed-block mode, the tape may not be correctly -positioned within a file when the device is closed. -With Linux 2.6, the -default is true for drives supporting SCSI-3. -.TP -.BR MT_ST_NO_BLKLIMS " (Default: false)" -Some drives don't accept the -.B "READ BLOCK LIMITS" -SCSI command. -If this is used, the driver does not use the command. -The drawback is -that the driver can't check before sending commands if the selected -block size is acceptable to the drive. -.TP -.BR MT_ST_CAN_PARTITIONS " (Default: false)" -This option enables support for several partitions within a -tape. -The option applies to all devices linked to a drive. -.TP -.BR MT_ST_SCSI2LOGICAL " (Default: false)" -This option instructs the driver to use the logical block addresses -defined in the SCSI-2 standard when performing the seek and tell -operations (both with -.B MTSEEK -and -.B MTIOCPOS -commands and when changing tape -partition). -Otherwise, the device-specific addresses are used. -It is highly advisable to set this option if the drive supports the -logical addresses because they count also filemarks. -There are some -drives that support only the logical block addresses. -.TP -.BR MT_ST_SYSV " (Default: false)" -When this option is enabled, the tape devices use the System V -semantics. -Otherwise, the BSD semantics are used. -The most important -difference between the semantics is what happens when a device used -for reading is closed: in System V semantics the tape is spaced forward -past the next filemark if this has not happened while using the -device. -In BSD semantics the tape position is not changed. -.TP -.BR MT_NO_WAIT " (Default: false)" -Enables immediate mode (i.e., don't wait for the command to finish) for some -commands (e.g., rewind). -.PP -An example: -.PP -.in +4n -.EX -struct mtop mt_cmd; -mt_cmd.mt_op = MTSETDRVBUFFER; -mt_cmd.mt_count = MT_ST_BOOLEANS | - MT_ST_BUFFER_WRITES | MT_ST_ASYNC_WRITES; -ioctl(fd, MTIOCTOP, mt_cmd); -.EE -.in -.PP -The default block size for a device can be set with -.B MT_ST_DEF_BLKSIZE -and the default density code can be set with -.BR MT_ST_DEFDENSITY . -The values for the parameters are or'ed -with the operation code. -.PP -With Linux 2.1.x and later, the timeout values can be set with the -subcommand -.B MT_ST_SET_TIMEOUT -ORed with the timeout in seconds. -The long timeout (used for rewinds and other commands -that may take a long time) can be set with -.BR MT_ST_SET_LONG_TIMEOUT . -The kernel defaults are very long to -make sure that a successful command is not timed out with any -drive. -Because of this, the driver may seem stuck even if it is only -waiting for the timeout. -These commands can be used to set more -practical values for a specific drive. -The timeouts set for one device -apply for all devices linked to the same drive. -.PP -Starting from Linux 2.4.19 and Linux 2.5.43, the driver supports a status -bit which indicates whether the drive requests cleaning. -The method used by the -drive to return cleaning information is set using the -.B MT_ST_SEL_CLN -subcommand. -If the value is zero, the cleaning -bit is always zero. -If the value is one, the TapeAlert data defined -in the SCSI-3 standard is used (not yet implemented). -Values 2\[en]17 are -reserved. -If the lowest eight bits are >= 18, bits from the extended -sense data are used. -The bits 9\[en]16 specify a mask to select the bits -to look at and the bits 17\[en]23 specify the bit pattern to look for. -If the bit pattern is zero, one or more bits under the mask indicate -the cleaning request. -If the pattern is nonzero, the pattern must match -the masked sense data byte. -.RE -.SS MTIOCGET \[em] get status -This request takes an argument of type -.IR "(struct mtget\ *)" . -.PP -.in +4n -.EX -/* structure for MTIOCGET \- mag tape get status command */ -struct mtget { - long mt_type; - long mt_resid; - /* the following registers are device dependent */ - long mt_dsreg; - long mt_gstat; - long mt_erreg; - /* The next two fields are not always used */ - daddr_t mt_fileno; - daddr_t mt_blkno; -}; -.EE -.in -.TP -\fImt_type\fP -The header file defines many values for -.IR mt_type , -but the current driver reports only the generic types -.B MT_ISSCSI1 -(Generic SCSI-1 tape) -and -.B MT_ISSCSI2 -(Generic SCSI-2 tape). -.TP -\fImt_resid\fP -contains the current tape partition number. -.TP -\fImt_dsreg\fP -reports the drive's current settings for block size (in the low 24 -bits) and density (in the high 8 bits). -These fields are defined by -.BR MT_ST_BLKSIZE_SHIFT , -.BR MT_ST_BLKSIZE_MASK , -.BR MT_ST_DENSITY_SHIFT , -and -.BR MT_ST_DENSITY_MASK . -.TP -\fImt_gstat\fP -reports generic (device independent) status information. -The header file defines macros for testing these status bits: -.RS -.TP -\fBGMT_EOF\fP(\fIx\fP) -The tape is positioned just after a filemark -(always false after an -.B MTSEEK -operation). -.TP -\fBGMT_BOT\fP(\fIx\fP) -The tape is positioned at the beginning of the first file (always false -after an -.B MTSEEK -operation). -.TP -\fBGMT_EOT\fP(\fIx\fP) -A tape operation has reached the physical End Of Tape. -.TP -\fBGMT_SM\fP(\fIx\fP) -The tape is currently positioned at a setmark -(always false after an -.B MTSEEK -operation). -.TP -\fBGMT_EOD\fP(\fIx\fP) -The tape is positioned at the end of recorded data. -.TP -\fBGMT_WR_PROT\fP(\fIx\fP) -The drive is write-protected. -For some drives this can also mean that the drive does not support -writing on the current medium type. -.TP -\fBGMT_ONLINE\fP(\fIx\fP) -The last -.BR open (2) -found the drive with a tape in place and ready for operation. -.TP -\fBGMT_D_6250\fP(\fIx\fP) -.TQ -\fBGMT_D_1600\fP(\fIx\fP) -.TQ -\fBGMT_D_800\fP(\fIx\fP) -This \[lq]generic\[rq] status information reports the current -density setting for 9-track \(12" tape drives only. -.TP -\fBGMT_DR_OPEN\fP(\fIx\fP) -The drive does not have a tape in place. -.TP -\fBGMT_IM_REP_EN\fP(\fIx\fP) -Immediate report mode. -This bit is set if there are no guarantees that -the data has been physically written to the tape when the write call -returns. -It is set zero only when the driver does not buffer data and -the drive is set not to buffer data. -.TP -\fBGMT_CLN\fP(\fIx\fP) -The drive has requested cleaning. -Implemented since Linux 2.4.19 and Linux 2.5.43. -.RE -.TP -\fImt_erreg\fP -The only field defined in -.I mt_erreg -is the recovered error count in the low 16 bits (as defined by -.B MT_ST_SOFTERR_SHIFT -and -.BR MT_ST_SOFTERR_MASK ). -Due to inconsistencies in the way drives report recovered errors, this -count is often not maintained (most drives do not by default report -soft errors but this can be changed with a SCSI MODE SELECT command). -.TP -\fImt_fileno\fP -reports the current file number (zero-based). -This value is set to \-1 when the file number is unknown (e.g., after -.B MTBSS -or -.BR MTSEEK ). -.TP -\fImt_blkno\fP -reports the block number (zero-based) within the current file. -This value is set to \-1 when the block number is unknown (e.g., after -.BR MTBSF , -.BR MTBSS , -or -.BR MTSEEK ). -.SS MTIOCPOS \[em] get tape position -This request takes an argument of type -.I "(struct mtpos\ *)" -and reports the drive's notion of the current tape block number, -which is not the same as -.I mt_blkno -returned by -.BR MTIOCGET . -This drive must be a SCSI-2 drive that supports the -.B "READ POSITION" -command (device-specific address) -or a Tandberg-compatible SCSI-1 drive (Tandberg, Archive -Viper, Wangtek, ... ). -.PP -.in +4n -.EX -/* structure for MTIOCPOS \- mag tape get position command */ -struct mtpos { - long mt_blkno; /* current block number */ -}; -.EE -.in -.SH RETURN VALUE -.TP -.B EACCES -An attempt was made to write or erase a write-protected tape. -(This error is not detected during -.BR open (2).) -.TP -.B EBUSY -The device is already in use or the driver was unable to allocate a -buffer. -.TP -.B EFAULT -The command parameters point to memory not belonging to the calling -process. -.TP -.B EINVAL -An -.BR ioctl (2) -had an invalid argument, or a requested block size was invalid. -.TP -.B EIO -The requested operation could not be completed. -.TP -.B ENOMEM -The byte count in -.BR read (2) -is smaller than the next physical block on the tape. -(Before Linux 2.2.18 and Linux 2.4.0 the extra bytes have been -.\" Precisely: Linux 2.6.0-test6 -silently ignored.) -.TP -.B ENOSPC -A write operation could not be completed because the tape reached -end-of-medium. -.TP -.B ENOSYS -Unknown -.BR ioctl (2). -.TP -.B ENXIO -During opening, the tape device does not exist. -.TP -.B EOVERFLOW -An attempt was made to read or write a variable-length block that is -larger than the driver's internal buffer. -.TP -.B EROFS -Open is attempted with -.B O_WRONLY -or -.B O_RDWR -when the tape in the drive is write-protected. -.SH FILES -.TP -.I /dev/st* -the auto-rewind SCSI tape devices -.TP -.I /dev/nst* -the nonrewind SCSI tape devices -.\" .SH AUTHOR -.\" The driver has been written by Kai M\(:akisara (Kai.Makisara@metla.fi) -.\" starting from a driver written by Dwayne Forsyth. -.\" Several other -.\" people have also contributed to the driver. -.SH NOTES -.IP \[bu] 3 -When exchanging data between systems, both systems have to agree on -the physical tape block size. -The parameters of a drive after startup -are often not the ones most operating systems use with these -devices. -Most systems use drives in variable-block mode if the drive -supports that mode. -This applies to most modern drives, including -DATs, 8mm helical scan drives, DLTs, etc. -It may be advisable to use -these drives in variable-block mode also in Linux (i.e., use -.B MTSETBLK -or -.B MTSETDEFBLK -at system startup to set the mode), at least when -exchanging data with a foreign system. -The drawback of -this is that a fairly large tape block size has to be used to get -acceptable data transfer rates on the SCSI bus. -.IP \[bu] -Many programs (e.g., -.BR tar (1)) -allow the user to specify the blocking -factor on the command line. -Note that this determines the physical block -size on tape only in variable-block mode. -.IP \[bu] -In order to use SCSI tape drives, the basic SCSI driver, -a SCSI-adapter driver and the SCSI tape driver must be either -configured into the kernel or loaded as modules. -If the SCSI-tape -driver is not present, the drive is recognized but the tape support -described in this page is not available. -.IP \[bu] -The driver writes error messages to the console/log. -The SENSE -codes written into some messages are automatically translated to text -if verbose SCSI messages are enabled in kernel configuration. -.IP \[bu] -The driver's internal buffering allows good throughput in fixed-block -mode also with small -.BR read (2) -and -.BR write (2) -byte counts. -With direct transfers -this is not possible and may cause a surprise when moving to the 2.6 -kernel. -The solution is to tell the software to use larger transfers (often -telling it to use larger blocks). -If this is not possible, direct transfers can be disabled. -.SH SEE ALSO -.BR mt (1) -.PP -The file -.I drivers/scsi/README.st -or -.I Documentation/scsi/st.txt -(kernel >= 2.6) in the Linux kernel source tree contains -the most recent information about the driver and its configuration -possibilities |