| Intro |
| ===== |
| |
| This file describes some issues involved when using the "ftape" |
| floppy tape device driver that comes with the Linux kernel. This |
| document deals with ftape-3.04 and later. Please read the section |
| "Changes" for the most striking differences between version 3.04 and |
| 2.08; the latter was the version of ftape delivered with the kernel |
| until kernel version 2.0.30 and 2.1.57. ftape-3.x developed as the |
| re-unification of ftape-2.x and zftape. zftape was developed in |
| parallel with the stock ftape-2.x driver sharing the same hardware |
| support but providing an enhanced file system interface. zftape also |
| provided user transparent block-wise on-the-fly compression (regard it |
| as a feature or bug of zftape). |
| |
| ftape has a home page at |
| |
| http://www-math.math.rwth-aachen.de/~LBFM/claus/ftape |
| |
| which contains further information about ftape. Please cross check |
| this WWW address against the address given (if any) in the MAINTAINERS |
| file located in the top level directory of the Linux kernel source |
| tree. |
| |
| Contents |
| ======== |
| |
| A minus 1: Ftape documentation |
| |
| A. Changes |
| 1. Goal |
| 2. I/O Block Size |
| 3. Write Access when not at EOD (End Of Data) or BOT (Begin Of Tape) |
| 4. MTBSF - backspace over file mark and position at its EOT side |
| 5. Formatting |
| 6. Interchanging cartridges with other operating systems |
| |
| B. Debugging Output |
| 1. Introduction |
| 2. Tuning the debugging output |
| |
| C. Boot and load time configuration |
| 1. Setting boot time parameters |
| 2. Module load time parameters |
| 3. Ftape boot- and load time options |
| 4. Example kernel parameter setting |
| 5. Example module parameter setting |
| |
| D. Support and contacts |
| |
| ******************************************************************************* |
| |
| A minus 1. Ftape documentation |
| ============================== |
| |
| Unluckily, the ftape-HOWTO is out of date. This really needs to be |
| changed. Up to date documentation as well as recent development |
| versions of ftape and useful links to related topics can be found at |
| the ftape home page at |
| |
| http://www-math.math.rwth-aachen.de/~LBFM/claus/ftape |
| |
| ******************************************************************************* |
| |
| A. Changes |
| ========== |
| |
| 1. Goal |
| ~~~~ |
| The goal of all that incompatibilities was to give ftape an interface |
| that resembles the interface provided by SCSI tape drives as close |
| as possible. Thus any Unix backup program that is known to work |
| with SCSI tape drives should also work with ftape-3.04 and above. |
| |
| The concept of a fixed block size for read/write transfers is |
| rather unrelated to this SCSI tape compatibility at the file system |
| interface level. It developed out of a feature of zftape, a |
| block wise user transparent on-the-fly compression. That compression |
| support will not be dropped in future releases for compatibility |
| reasons with previous releases of zftape. |
| |
| 2. I/O Block Size |
| ~~~~~~~~~~~~~~ |
| The probably most striking difference between ftape-2.x and |
| ftape-3.x with the zftape file system interface is the concept of a |
| fixed block size: data must be written to or read from the tape in |
| multiples of a fixed block size. The block size defaults to 10k |
| which is the default block size of GNU tar. While this is quite |
| usual for SCSI tapes (block size of 32k?) and the QIC-150 driver |
| `./drivers/char/tpqic02.c' ftape-2.x allowed data to be written in |
| arbitrary portions to the tape. |
| |
| The block size can be tuned either during kernel configuration or |
| at runtime with the MTIOCTOP ioctl using the MTSETBLK operation |
| (i.e. do "mt -f /dev/qft0" setblk #BLKSZ). A block size of 0 |
| switches to variable block size mode i.e. "mt setblk 0" switches |
| off the block size restriction. However, this disables zftape's |
| built in on-the-fly compression which doesn't work with variable |
| block size mode. |
| |
| The BLKSZ parameter must be given as a byte count and must be a |
| multiple of 32k or 0, i.e. use "mt setblk 32768" to switch to a |
| block size of 32k. |
| |
| The typical symptom of a block size mismatch is an "invalid |
| argument" error message. |
| |
| 3. Write Access when not at EOD (End Of Data) or BOT (Begin Of Tape) |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| zftape (the file system interface of ftape-3.x) denies write access |
| to the tape cartridge when it isn't positioned either at BOT or |
| EOD. This inconvenience has been introduced as it was reported that |
| the former behavior of ftape-2.x which allowed write access at |
| arbitrary locations already has caused data loss with some backup |
| programs. |
| |
| 4. MTBSF - backspace over file mark and position at its EOT side |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| ftape-2.x didn't handle the MTBSF tape operation correctly. A MTBSF |
| call (i.e. "mt -f /dev/nqft0 bsf #COUNT") should space over #COUNT |
| file marks and then position at the EOT tape side of the file |
| mark. This has to be taken literally, i.e. "mt -f /dev/nqft0 bsf 1" |
| should simply position at the start of the current volume. |
| |
| 5. Formatting |
| ~~~~~~~~~~ |
| ftape-3.x DOES support formatting of floppy tape cartridges. You |
| need the `ftformat' program that is shipped with the modules version |
| of ftape-3.x. Please get the latest version of ftape from |
| |
| ftp://sunsite.unc.edu/pub/Linux/kernel/tapes |
| |
| or from the ftape home page at |
| |
| http://www-math.math.rwth-aachen.de/~LBFM/claus/ftape |
| |
| `ftformat' is contained in the `./contrib/' subdirectory of that |
| separate ftape package. |
| |
| 6. Interchanging cartridges with other operating systems |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| The internal emulation of Unix tape device file marks has changed |
| completely. ftape-3.x now uses the volume table segment as specified |
| by the QIC-40/80/3010/3020/113 standards to emulate file marks. As |
| a consequence there is limited support to interchange cartridges |
| with other operating systems. |
| |
| To be more precise: ftape will detect volumes written by other OS's |
| programs and other OS's programs will detect volumes written by |
| ftape-3.x. |
| |
| However, it isn't possible to extract the data dumped to the tape |
| by some MSDOG program with ftape-3.x. This exceeds the scope of a |
| kernel device driver. If you need such functionality, then go ahead |
| and write a user space utility that is able to do |
| that. ftape-3.x/zftape already provides all kernel level support |
| necessary to do that. |
| |
| ******************************************************************************* |
| |
| B. Debugging Output |
| ================ |
| |
| 1. Introduction |
| ~~~~~~~~~~~~ |
| The ftape driver can be very noisy in that is can print lots of |
| debugging messages to the kernel log files and the system console. |
| While this is useful for debugging it might be annoying during |
| normal use and enlarges the size of the driver by several kilobytes. |
| |
| To reduce the size of the driver you can trim the maximal amount of |
| debugging information available during kernel configuration. Please |
| refer to the kernel configuration script and its on-line help |
| functionality. |
| |
| The amount of debugging output maps to the "tracing" boot time |
| option and the "ft_tracing" modules option as follows: |
| |
| 0 bugs |
| 1 + errors (with call-stack dump) |
| 2 + warnings |
| 3 + information |
| 4 + more information |
| 5 + program flow |
| 6 + fdc/dma info |
| 7 + data flow |
| 8 + everything else |
| |
| 2. Tuning the debugging output |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| To reduce the amount of debugging output printed to the system |
| console you can |
| |
| i) trim the debugging output at run-time with |
| |
| mt -f /dev/nqft0 setdensity #DBGLVL |
| |
| where "#DBGLVL" is a number between 0 and 9 |
| |
| ii) trim the debugging output at module load time with |
| |
| insmod ftape.o ft_tracing=#DBGLVL |
| |
| Of course, this applies only if you have configured ftape to be |
| compiled as a module. |
| |
| iii) trim the debugging output during system boot time. Add the |
| following to the kernel command line: |
| |
| ftape=#DBGLVL,tracing |
| |
| Please refer also to the next section if you don't know how to |
| set boot time parameters. |
| |
| ******************************************************************************* |
| |
| C. Boot and load time configuration |
| ================================ |
| |
| 1. Setting boot time parameters |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| Assuming that you use lilo, the LI)nux LO)ader, boot time kernel |
| parameters can be set by adding a line |
| |
| append some_kernel_boot_time_parameter |
| |
| to `/etc/lilo.conf' or at real boot time by typing in the options |
| at the prompt provided by LILO. I can't give you advice on how to |
| specify those parameters with other loaders as I don't use them. |
| |
| For ftape, each "some_kernel_boot_time_parameter" looks like |
| "ftape=value,option". As an example, the debugging output can be |
| increased with |
| |
| ftape=4,tracing |
| |
| NOTE: the value precedes the option name. |
| |
| 2. Module load time parameters |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| Module parameters can be specified either directly when invoking |
| the program 'insmod' at the shell prompt: |
| |
| insmod ftape.o ft_tracing=4 |
| |
| or by editing the file `/etc/modules.conf' in which case they take |
| effect each time when the module is loaded with `modprobe' (please |
| refer to the modules documentation, i.e. `modules.txt' and the |
| respective manual pages). Thus, you should add a line |
| |
| options ftape ft_tracing=4 |
| |
| to `/etc/modules.conf` if you intend to increase the debugging |
| output of the driver. |
| |
| |
| 3. Ftape boot- and load time options |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| |
| i. Controlling the amount of debugging output |
| DBGLVL has to be replaced by a number between 0 and 8. |
| |
| module | kernel command line |
| -----------------------|---------------------- |
| ft_tracing=DBGLVL | ftape=DBGLVL,tracing |
| |
| ii. Hardware setup |
| BASE is the base address of your floppy disk controller, |
| IRQ and DMA give its interrupt and DMA channel, respectively. |
| BOOL is an integer, "0" means "no"; any other value means |
| "yes". You don't need to specify anything if connecting your tape |
| drive to the standard floppy disk controller. All of these |
| values have reasonable defaults. The defaults can be modified |
| during kernel configuration, i.e. while running "make config", |
| "make menuconfig" or "make xconfig" in the top level directory |
| of the Linux kernel source tree. Please refer also to the on |
| line documentation provided during that kernel configuration |
| process. |
| |
| module | kernel command line |
| -----------------------|---------------------- |
| ft_fdc_base=BASE | ftape=BASE,ioport |
| ft_fdc_irq=IRQ | ftape=IRQ,irq |
| ft_fdc_dma=DMA | ftape=DMA,dma |
| ft_probe_fc10=BOOL | ftape=BOOL,fc10 |
| ft_mach2=BOOL | ftape=BOOL,mach2 |
| ft_fdc_threshold=THR | ftape=THR,threshold |
| ft_fdc_rate_limit=RATE | ftape=RATE,datarate |
| |
| 4. Example kernel parameter setting |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| To configure ftape to probe for a Colorado FC-10/FC-20 controller |
| and to increase the amount of debugging output a little bit, add |
| the following line to `/etc/lilo.conf': |
| |
| append ftape=1,fc10 ftape=4,tracing |
| |
| 5. Example module parameter setting |
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| To do the same, but with ftape compiled as a loadable kernel |
| module, add the following line to `/etc/modules.conf': |
| |
| options ftape ft_probe_fc10=1 ft_tracing=4 |
| |
| ******************************************************************************* |
| |
| D. Support and contacts |
| ==================== |
| |
| Ftape is distributed under the GNU General Public License. There is |
| absolutely no warranty for this software. However, you can reach |
| the current maintainer of the ftape package under the email address |
| given in the MAINTAINERS file which is located in the top level |
| directory of the Linux kernel source tree. There you'll find also |
| the relevant mailing list to use as a discussion forum and the web |
| page to query for the most recent documentation, related work and |
| development versions of ftape. |
| |
| |
| LocalWords: ftape Linux zftape http www rwth aachen LBFM claus EOD config |
| LocalWords: datarate LocalWords BOT MTBSF EOT HOWTO QIC tpqic menuconfig |
| LocalWords: MTIOCTOP MTSETBLK mt dev qft setblk BLKSZ bsf zftape's xconfig |
| LocalWords: nqft ftformat ftp sunsite unc edu contrib ft MSDOG fdc |
| LocalWords: dma setdensity DBGLVL insmod lilo LI nux ader conf txt |
| LocalWords: modprobe IRQ BOOL ioport irq fc mach THR |
