Lines Matching +full:write +full:- +full:to +full:- +full:read

15 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
39 devices of the sequential access class that are attached to the system
62 The tape can be unmounted, bringing the session to a
65 .Bl -enum
68 referred to as sub-mode 00 below.
83 access is only sought when needed (e.g., to set parameters).
84 .Sh SUB-MODES
86 .Sq sub-modes .
87 The sub-modes differ in the action taken when the device is closed:
88 .Bl -tag -width XXXX
95 If the tape was written to, a file mark will be written.
98 last read, or the written file mark.
112 block-size modes.
114 .Tn QIC Ns -type
115 devices run in fixed block-size mode, where most nine-track tapes and
116 many new cartridge formats allow variable block-size.
118 .Bl -inset
119 .It Variable block-size:
120 Each write made to the device results in a single logical record
121 written to the tape.
122 One can never read or write
124 of a record from tape (though you may request a larger block and read
125 a smaller record); nor can one read multiple blocks.
126 Data from a single write is therefore read by a single read.
134 logically considered to be immediately after the last item read,
137 but it was never read, then the next
138 process to read will immediately hit the file mark and receive an end-of-file notification.
139 .It Fixed block-size:
140 Data written by the user is passed to the tape as a succession of
143 considered to be a series of independent blocks.
144 One may never write
146 One may read and write the same data as a different set of records.
147 In other words, blocks that were written together may be read separately,
148 and vice-versa.
152 As there is some data to return (unless
153 there were no records before the file mark), the read will succeed,
155 The next read will return immediately with a value
157 (As above, if the file mark is never read, it remains for the next
158 process to read if in no-rewind mode.)
161 By default, the driver will NOT accept reads or writes to a tape device that
162 are larger than may be written to or read from the mounted tape using a single
163 write or read request.
165 are respected in terms of the block size written to tape.
166 For example, if the user tries to write a 256KB block to the tape, but the
167 controller can handle no more than 128KB, the write will fail.
170 behavior, prior to
173 was to break up large reads or writes into smaller blocks when going to the
175 The problem with that behavior, though, is that it hides the actual on-tape
183 .Bl -tag -width 12
186 This variable, when set to 1, will configure all
188 devices to split large buffers into smaller pieces when needed.
191 This variable, when set to 1, will configure the given
193 unit to split large buffers into multiple pieces.
199 variables available to view block handling parameters:
200 .Bl -tag -width 12
203 This variable allows the user to see, but not modify, the current I/O split
205 The user is not permitted to modify this setting so that there is no chance
211 capabilities of the controller that is attached to the tape drive.
216 READ BLOCK LIMITS command.
225 The handling of file marks on write is automatic.
227 written to the tape, and has not done a read since the last write,
228 then a file mark will be written to the tape when the device is
230 If a rewind is requested after a write, then the driver
232 that there are two file marks written to the tape.
233 The exception to
234 this is that there seems to be a standard (which we follow, but do not
235 understand why) that certain types of tape do not actually write two
236 file marks to tape, but when read, report a `phantom' file mark when the
237 last file is read.
248 .Dq mt param -l
252 .Dq mt param -s
263 .Bl -tag -width 5n
266 When set to 1, it sets the Suppress Incorrect Length Indicator (SILI) bit
272 See the SSC-5 spec (available at t10.org), specifically the section on the
273 READ(6) command, for more information.
279 of Media conditions by returning a write with 0 bytes written, and
281 set to 0.
284 is set to 1, the
292 This is a read-only parameter, and is set to 1 if the tape drive supports
295 If protection is supported, set this to the desired protection method
297 As of SSC-5r03 (available at t10.org), the protection method values are:
298 .Bl -tag -width 3n
302 Reed-Solomon CRC, 4 bytes in length.
309 If set to 1, enable logical block protection on writes.
310 The CRC must be appended to the end of the block written to the tape driver.
313 If set to 1, enable logical block protection on reads.
314 The CRC will be appended to the end of the block read from the tape driver.
317 If set to 1, enable logical block protection on the RECOVER BUFFERED DATA
327 driver has a set of default timeouts for SCSI commands (READ, WRITE, TEST UNIT
330 For newer tape drives that claim to support the SPC-4
333 driver will attempt to use the REPORT SUPPORTED OPERATION CODES command to
352 subcommand) it is generally best to use those values.
366 To set timeouts after boot, the per-instance timeout values, for example:
367 .Va kern.cam.sa.0.timeout.read ,
370 If a tape drive arrives after boot, the global tunables or per-instance
371 tunables that apply to the newly arrived drive will be used.
375 .Bl -tag -compact
381 .It kern.cam.sa.timeout.read
389 .It kern.cam.sa.timeout.write
397 .Bl -tag -compact
403 .It kern.cam.sa.%d.timeout.read
411 .It kern.cam.sa.%d.timeout.write
417 of a second, so be sure to account for that when setting them.
424 .Bl -tag -width /dev/[n][e]sa[0-9] -compact
425 .It Pa /dev/[n][e]sa[0-9]
434 Control mode device (to examine state while another program is
440 driver supports injecting End Of Media (EOM) notification to aid
442 EOM is indicated to the application by returning the read or write with 0
455 sysctl variable to 1.
457 query, and then the driver state will be reset to normal.
462 .An -nosplit
485 This driver lacks many of the hacks required to deal with older devices.
487 .Tn SCSI-1
494 are not automatically read correctly with this driver: you may need to
495 explicitly set variable block mode or set to the blocksize that works best
496 for your device in order to read tapes written under
501 It would be nice to add support for creating and editing tape partitions.