1Intro 2===== 3 4This file describes some issues involved when using the "ftape" 5floppy tape device driver that comes with the Linux kernel. This 6document deals with ftape-3.04 and later. Please read the section 7"Changes" for the most striking differences between version 3.04 and 82.08; the latter was the version of ftape delivered with the kernel 9until kernel version 2.0.30 and 2.1.57. ftape-3.x developed as the 10re-unification of ftape-2.x and zftape. zftape was developed in 11parallel with the stock ftape-2.x driver sharing the same hardware 12support but providing an enhanced file system interface. zftape also 13provided user transparent block-wise on-the-fly compression (regard it 14as a feature or bug of zftape). 15 16ftape has a home page at 17 18http://www-math.math.rwth-aachen.de/~LBFM/claus/ftape 19 20which contains further information about ftape. Please cross check 21this WWW address against the address given (if any) in the MAINTAINERS 22file located in the top level directory of the Linux kernel source 23tree. 24 25Contents 26======== 27 28A minus 1: Ftape documentation 29 30A. Changes 31 1. Goal 32 2. I/O Block Size 33 3. Write Access when not at EOD (End Of Data) or BOT (Begin Of Tape) 34 4. MTBSF - backspace over file mark and position at its EOT side 35 5. Formatting 36 6. Interchanging cartridges with other operating systems 37 38B. Debugging Output 39 1. Introduction 40 2. Tuning the debugging output 41 42C. Boot and load time configuration 43 1. Setting boot time parameters 44 2. Module load time parameters 45 3. Ftape boot- and load time options 46 4. Example kernel parameter setting 47 5. Example module parameter setting 48 49D. Support and contacts 50 51******************************************************************************* 52 53A minus 1. Ftape documentation 54============================== 55 56Unluckily, the ftape-HOWTO is out of date. This really needs to be 57changed. Up to date documentation as well as recent development 58versions of ftape and useful links to related topics can be found at 59the ftape home page at 60 61http://www-math.math.rwth-aachen.de/~LBFM/claus/ftape 62 63******************************************************************************* 64 65A. Changes 66========== 67 681. Goal 69 ~~~~ 70 The goal of all that incompatibilities was to give ftape an interface 71 that resembles the interface provided by SCSI tape drives as close 72 as possible. Thus any Unix backup program that is known to work 73 with SCSI tape drives should also work with ftape-3.04 and above. 74 75 The concept of a fixed block size for read/write transfers is 76 rather unrelated to this SCSI tape compatibility at the file system 77 interface level. It developed out of a feature of zftape, a 78 block wise user transparent on-the-fly compression. That compression 79 support will not be dropped in future releases for compatibility 80 reasons with previous releases of zftape. 81 822. I/O Block Size 83 ~~~~~~~~~~~~~~ 84 The probably most striking difference between ftape-2.x and 85 ftape-3.x with the zftape file system interface is the concept of a 86 fixed block size: data must be written to or read from the tape in 87 multiples of a fixed block size. The block size defaults to 10k 88 which is the default block size of GNU tar. While this is quite 89 usual for SCSI tapes (block size of 32k?) and the QIC-150 driver 90 `./drivers/char/tpqic02.c' ftape-2.x allowed data to be written in 91 arbitrary portions to the tape. 92 93 The block size can be tuned either during kernel configuration or 94 at runtime with the MTIOCTOP ioctl using the MTSETBLK operation 95 (i.e. do "mt -f /dev/qft0" setblk #BLKSZ). A block size of 0 96 switches to variable block size mode i.e. "mt setblk 0" switches 97 off the block size restriction. However, this disables zftape's 98 built in on-the-fly compression which doesn't work with variable 99 block size mode. 100 101 The BLKSZ parameter must be given as a byte count and must be a 102 multiple of 32k or 0, i.e. use "mt setblk 32768" to switch to a 103 block size of 32k. 104 105 The typical symptom of a block size mismatch is an "invalid 106 argument" error message. 107 1083. Write Access when not at EOD (End Of Data) or BOT (Begin Of Tape) 109 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 110 zftape (the file system interface of ftape-3.x) denies write access 111 to the tape cartridge when it isn't positioned either at BOT or 112 EOD. This inconvenience has been introduced as it was reported that 113 the former behavior of ftape-2.x which allowed write access at 114 arbitrary locations already has caused data loss with some backup 115 programs. 116 1174. MTBSF - backspace over file mark and position at its EOT side 118 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 119 ftape-2.x didn't handle the MTBSF tape operation correctly. A MTBSF 120 call (i.e. "mt -f /dev/nqft0 bsf #COUNT") should space over #COUNT 121 file marks and then position at the EOT tape side of the file 122 mark. This has to be taken literally, i.e. "mt -f /dev/nqft0 bsf 1" 123 should simply position at the start of the current volume. 124 1255. Formatting 126 ~~~~~~~~~~ 127 ftape-3.x DOES support formatting of floppy tape cartridges. You 128 need the `ftformat' program that is shipped with the modules version 129 of ftape-3.x. Please get the latest version of ftape from 130 131 ftp://sunsite.unc.edu/pub/Linux/kernel/tapes 132 133 or from the ftape home page at 134 135 http://www-math.math.rwth-aachen.de/~LBFM/claus/ftape 136 137 `ftformat' is contained in the `./contrib/' subdirectory of that 138 separate ftape package. 139 1406. Interchanging cartridges with other operating systems 141 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 142 143 The internal emulation of Unix tape device file marks has changed 144 completely. ftape-3.x now uses the volume table segment as specified 145 by the QIC-40/80/3010/3020/113 standards to emulate file marks. As 146 a consequence there is limited support to interchange cartridges 147 with other operating systems. 148 149 To be more precise: ftape will detect volumes written by other OS's 150 programs and other OS's programs will detect volumes written by 151 ftape-3.x. 152 153 However, it isn't possible to extract the data dumped to the tape 154 by some MSDOG program with ftape-3.x. This exceeds the scope of a 155 kernel device driver. If you need such functionality, then go ahead 156 and write a user space utility that is able to do 157 that. ftape-3.x/zftape already provides all kernel level support 158 necessary to do that. 159 160******************************************************************************* 161 162B. Debugging Output 163 ================ 164 1651. Introduction 166 ~~~~~~~~~~~~ 167 The ftape driver can be very noisy in that is can print lots of 168 debugging messages to the kernel log files and the system console. 169 While this is useful for debugging it might be annoying during 170 normal use and enlarges the size of the driver by several kilobytes. 171 172 To reduce the size of the driver you can trim the maximal amount of 173 debugging information available during kernel configuration. Please 174 refer to the kernel configuration script and its on-line help 175 functionality. 176 177 The amount of debugging output maps to the "tracing" boot time 178 option and the "ft_tracing" modules option as follows: 179 180 0 bugs 181 1 + errors (with call-stack dump) 182 2 + warnings 183 3 + information 184 4 + more information 185 5 + program flow 186 6 + fdc/dma info 187 7 + data flow 188 8 + everything else 189 1902. Tuning the debugging output 191 ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 192 To reduce the amount of debugging output printed to the system 193 console you can 194 195 i) trim the debugging output at run-time with 196 197 mt -f /dev/nqft0 setdensity #DBGLVL 198 199 where "#DBGLVL" is a number between 0 and 9 200 201 ii) trim the debugging output at module load time with 202 203 insmod ftape.o ft_tracing=#DBGLVL 204 205 Of course, this applies only if you have configured ftape to be 206 compiled as a module. 207 208 iii) trim the debugging output during system boot time. Add the 209 following to the kernel command line: 210 211 ftape=#DBGLVL,tracing 212 213 Please refer also to the next section if you don't know how to 214 set boot time parameters. 215 216******************************************************************************* 217 218C. Boot and load time configuration 219 ================================ 220 2211. Setting boot time parameters 222 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 223 Assuming that you use lilo, the LI)nux LO)ader, boot time kernel 224 parameters can be set by adding a line 225 226 append some_kernel_boot_time_parameter 227 228 to `/etc/lilo.conf' or at real boot time by typing in the options 229 at the prompt provided by LILO. I can't give you advice on how to 230 specify those parameters with other loaders as I don't use them. 231 232 For ftape, each "some_kernel_boot_time_parameter" looks like 233 "ftape=value,option". As an example, the debugging output can be 234 increased with 235 236 ftape=4,tracing 237 238 NOTE: the value precedes the option name. 239 2402. Module load time parameters 241 ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 242 Module parameters can be specified either directly when invoking 243 the program 'insmod' at the shell prompt: 244 245 insmod ftape.o ft_tracing=4 246 247 or by editing the file `/etc/modules.conf' in which case they take 248 effect each time when the module is loaded with `modprobe' (please 249 refer to the respective manual pages). Thus, you should add a line 250 251 options ftape ft_tracing=4 252 253 to `/etc/modules.conf` if you intend to increase the debugging 254 output of the driver. 255 256 2573. Ftape boot- and load time options 258 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 259 260 i. Controlling the amount of debugging output 261 DBGLVL has to be replaced by a number between 0 and 8. 262 263 module | kernel command line 264 -----------------------|---------------------- 265 ft_tracing=DBGLVL | ftape=DBGLVL,tracing 266 267 ii. Hardware setup 268 BASE is the base address of your floppy disk controller, 269 IRQ and DMA give its interrupt and DMA channel, respectively. 270 BOOL is an integer, "0" means "no"; any other value means 271 "yes". You don't need to specify anything if connecting your tape 272 drive to the standard floppy disk controller. All of these 273 values have reasonable defaults. The defaults can be modified 274 during kernel configuration, i.e. while running "make config", 275 "make menuconfig" or "make xconfig" in the top level directory 276 of the Linux kernel source tree. Please refer also to the on 277 line documentation provided during that kernel configuration 278 process. 279 280 module | kernel command line 281 -----------------------|---------------------- 282 ft_fdc_base=BASE | ftape=BASE,ioport 283 ft_fdc_irq=IRQ | ftape=IRQ,irq 284 ft_fdc_dma=DMA | ftape=DMA,dma 285 ft_probe_fc10=BOOL | ftape=BOOL,fc10 286 ft_mach2=BOOL | ftape=BOOL,mach2 287 ft_fdc_threshold=THR | ftape=THR,threshold 288 ft_fdc_rate_limit=RATE | ftape=RATE,datarate 289 2904. Example kernel parameter setting 291 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 292 To configure ftape to probe for a Colorado FC-10/FC-20 controller 293 and to increase the amount of debugging output a little bit, add 294 the following line to `/etc/lilo.conf': 295 296 append ftape=1,fc10 ftape=4,tracing 297 2985. Example module parameter setting 299 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 300 To do the same, but with ftape compiled as a loadable kernel 301 module, add the following line to `/etc/modules.conf': 302 303 options ftape ft_probe_fc10=1 ft_tracing=4 304 305******************************************************************************* 306 307D. Support and contacts 308 ==================== 309 310 Ftape is distributed under the GNU General Public License. There is 311 absolutely no warranty for this software. However, you can reach 312 the current maintainer of the ftape package under the email address 313 given in the MAINTAINERS file which is located in the top level 314 directory of the Linux kernel source tree. There you'll find also 315 the relevant mailing list to use as a discussion forum and the web 316 page to query for the most recent documentation, related work and 317 development versions of ftape. 318 319 320 LocalWords: ftape Linux zftape http www rwth aachen LBFM claus EOD config 321 LocalWords: datarate LocalWords BOT MTBSF EOT HOWTO QIC tpqic menuconfig 322 LocalWords: MTIOCTOP MTSETBLK mt dev qft setblk BLKSZ bsf zftape's xconfig 323 LocalWords: nqft ftformat ftp sunsite unc edu contrib ft MSDOG fdc 324 LocalWords: dma setdensity DBGLVL insmod lilo LI nux ader conf txt 325 LocalWords: modprobe IRQ BOOL ioport irq fc mach THR 326