Lines Matching +full:buffer +full:- +full:size
1 .. SPDX-License-Identifier: GPL-2.0
23 flexible method and applicable to single-user workstations. However,
28 parameters, like block size and density using the MTSETDRVBUFFER ioctl.
32 drive performs auto-detection of the tape format well (like some
33 QIC-drives). The result is that any tape can be read, writing can be
37 does not perform auto-detection well enough and there is a single
40 or not :-).
57 between formats in multi-tape operations (the explicitly overridden
71 The driver supports fixed and variable block size (within buffer
72 limits). Both the auto-rewind (minor equals device number) and
73 non-rewind devices (minor is 128 + device number) are implemented.
75 In variable block mode, the byte count in write() determines the size
78 is at least the block size. Otherwise, error ENOMEM is returned.
81 driver is in multiples of the block size. The write() byte count must
82 be a multiple of the block size. This is not required when reading but
100 write the filemarks without flushing the drive buffer. Writing filemark at
128 dev_upper non-rew mode dev-lower
129 20 - 8 7 6 5 4 0
131 The non-rewind bit is always bit 7 (the uppermost bit in the lowermost
132 byte). The bits defining the mode are below the non-rewind bit. The
143 and non-rewind entries for each mode. The names are stxy and nstxy, where x
151 the defaults set by the user. The value -1 means the default is not set. The
161 directory corresponding to the mode 0 auto-rewind device (e.g., st0).
174 regular expression "^st[0-9]+$"
186 - The number of I/Os currently outstanding to this device.
188 - The amount of time spent waiting (in nanoseconds) for all I/O
193 - The number of I/Os issued to the tape drive other than read or
195 following calculation io_ms-read_ms-write_ms.
197 - The number of bytes read from the tape drive.
199 - The number of read requests issued to the tape drive.
201 - The amount of time (in nanoseconds) spent waiting for read
204 - The number of bytes written to the tape drive.
206 - The number of write requests issued to the tape drive.
208 - The amount of time (in nanoseconds) spent waiting for write
211 - The number of times during a read or write we found
212 the residual amount to be non-zero. This should mean that a program
213 is issuing a read larger thean the block size on tape. For write
252 is not possible, a driver buffer allocated at run-time is used. If
253 direct i/o is not possible for the whole transfer, the driver buffer
257 - one or more pages are at addresses not reachable by the HBA
258 - the number of pages in the transfer exceeds the number of
260 - one or more pages can't be locked into memory (should not happen in
263 The size of the driver buffers is always at least one tape block. In fixed
264 block mode, the minimum buffer size is defined (in 1024 byte units) by
265 ST_FIXED_BUFFER_BLOCKS. With small block size this allows buffering of
268 allowed if ST_BUFFER_WRITES is non-zero and direct i/o is not used.
269 Buffer allocation uses chunks of memory having sizes 2^n * (page
270 size). Because of this the actual buffer size may be larger than the
271 minimum allowable buffer size.
275 -b option) may have had good throughput but this is not true any more with
277 is to use bigger write() byte counts (e.g., tar -b 64).
279 Asynchronous writing. Writing the buffer contents to the tape is
286 tape after the early-warning mark to flush the driver buffer.
288 Read ahead for fixed block mode (ST_READ_AHEAD). Filling the buffer is
293 Scatter/gather buffers (buffers that consist of chunks non-contiguous
296 supporting scatter/gather), buffer allocation is using the following
300 those not supporting scatter/gather. The size of this buffer will be
302 this size (and it is not larger than the buffer size specified by
303 ST_BUFFER_BLOCKS). If this size is not available, the driver halves
304 the size and tries again until the size of one page. The default
306 buffer as one chunk.
307 2. The scatter/gather segments to fill the specified buffer size are
312 are used to extend the buffer at run-time if this is necessary. The
317 extending the buffer will always fail.
325 returns -1 and errno is set to ENOSPC. To enable writing a trailer,
327 bytes is returned. After this, -1 and the number of bytes are
334 The buffer size, write threshold, and the maximum number of allocated buffers
338 buffer_kbs=xxx the buffer size for fixed block mode is set
343 try_direct_io=x try direct transfer between user buffer and
344 tape drive if this is non-zero
347 Note that if the buffer size is changed but the write threshold is not
348 set, the write threshold is set to the new buffer size - 2 kB.
363 the driver as module. If several parameters are set, the keyword-value
376 - aa is the buffer size for fixed block mode in 1024 byte units
377 - bb is the write threshold in 1024 byte units
378 - dd is the maximum number of scatter/gather segments
388 (look for a package mt-st* from the Linux ftp sites; the GNU mt does
426 Re-tension tape.
434 Seek to tape block count. Uses Tandberg-compatible seek (QFA)
435 for SCSI-1 drives and SCSI-2 seek for SCSI-2 drives. The file and
438 Set the drive block size. Setting to zero sets the drive into
469 partitions (argument non-zero). If the argument is positive,
470 it specifies the size of partition 1 in megabytes. For DDS
473 value specifies the size of partition 0 in megabytes. This is
475 LTO drives from LTO-5 upwards. The drive has to support partitions
476 with size specified by the initiator. Inactive unless
485 The drive buffer option is set to the argument. Zero means
512 from the drive (block size can be changed only to
519 the MTSEEK and MTIOCPOS for SCSI-2 drives instead of
549 Defines the default block size set automatically. Value
552 Used to set or clear the density (8 bits), and drive buffer
560 contains the new default. If the bits 8-15 are set to a
561 non-zero number, and this number is not 0xff, the number is
581 cleaning. The bits are device-dependent. The driver is
583 bits of the argument; must be >= 18 (values 1 - 17
585 a mask to select the relevant bits (the bits 9-16), and the
586 bit pattern (bits 17-23). If the bit pattern is zero, one
588 the pattern is non-zero, the pattern must match the masked
599 Tandberg-compatible QFA for SCSI-1 drives and the SCSI-2
600 command for the SCSI-2 drives.
607 block is -1 when it can't be determined (e.g., after MTBSF).
611 The current block size and the density code are stored in the field
663 the driver is waiting. With the command 'ps -l' you can see the state