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diff --git a/Documentation/s390/TAPE b/Documentation/s390/TAPE new file mode 100644 index 000000000000..c639aa5603ff --- /dev/null +++ b/Documentation/s390/TAPE @@ -0,0 +1,122 @@ +Channel attached Tape device driver + +-----------------------------WARNING----------------------------------------- +This driver is considered to be EXPERIMENTAL. Do NOT use it in +production environments. Feel free to test it and report problems back to us. +----------------------------------------------------------------------------- + +The LINUX for zSeries tape device driver manages channel attached tape drives +which are compatible to IBM 3480 or IBM 3490 magnetic tape subsystems. This +includes various models of these devices (for example the 3490E). + + +Tape driver features + +The device driver supports a maximum of 128 tape devices. +No official LINUX device major number is assigned to the zSeries tape device +driver. It allocates major numbers dynamically and reports them on system +startup. +Typically it will get major number 254 for both the character device front-end +and the block device front-end. + +The tape device driver needs no kernel parameters. All supported devices +present are detected on driver initialization at system startup or module load. +The devices detected are ordered by their subchannel numbers. The device with +the lowest subchannel number becomes device 0, the next one will be device 1 +and so on. + + +Tape character device front-end + +The usual way to read or write to the tape device is through the character +device front-end. The zSeries tape device driver provides two character devices +for each physical device -- the first of these will rewind automatically when +it is closed, the second will not rewind automatically. + +The character device nodes are named /dev/rtibm0 (rewinding) and /dev/ntibm0 +(non-rewinding) for the first device, /dev/rtibm1 and /dev/ntibm1 for the +second, and so on. + +The character device front-end can be used as any other LINUX tape device. You +can write to it and read from it using LINUX facilities such as GNU tar. The +tool mt can be used to perform control operations, such as rewinding the tape +or skipping a file. + +Most LINUX tape software should work with either tape character device. + + +Tape block device front-end + +The tape device may also be accessed as a block device in read-only mode. +This could be used for software installation in the same way as it is used with +other operation systems on the zSeries platform (and most LINUX +distributions are shipped on compact disk using ISO9660 filesystems). + +One block device node is provided for each physical device. These are named +/dev/btibm0 for the first device, /dev/btibm1 for the second and so on. +You should only use the ISO9660 filesystem on LINUX for zSeries tapes because +the physical tape devices cannot perform fast seeks and the ISO9660 system is +optimized for this situation. + + +Tape block device example + +In this example a tape with an ISO9660 filesystem is created using the first +tape device. ISO9660 filesystem support must be built into your system kernel +for this. +The mt command is used to issue tape commands and the mkisofs command to +create an ISO9660 filesystem: + +- create a LINUX directory (somedir) with the contents of the filesystem + mkdir somedir + cp contents somedir + +- insert a tape + +- ensure the tape is at the beginning + mt -f /dev/ntibm0 rewind + +- set the blocksize of the character driver. The blocksize 2048 bytes + is commonly used on ISO9660 CD-Roms + mt -f /dev/ntibm0 setblk 2048 + +- write the filesystem to the character device driver + mkisofs -o /dev/ntibm0 somedir + +- rewind the tape again + mt -f /dev/ntibm0 rewind + +- Now you can mount your new filesystem as a block device: + mount -t iso9660 -o ro,block=2048 /dev/btibm0 /mnt + +TODO List + + - Driver has to be stabilized still + +BUGS + +This driver is considered BETA, which means some weaknesses may still +be in it. +If an error occurs which cannot be handled by the code you will get a +sense-data dump.In that case please do the following: + +1. set the tape driver debug level to maximum: + echo 6 >/proc/s390dbf/tape/level + +2. re-perform the actions which produced the bug. (Hopefully the bug will + reappear.) + +3. get a snapshot from the debug-feature: + cat /proc/s390dbf/tape/hex_ascii >somefile + +4. Now put the snapshot together with a detailed description of the situation + that led to the bug: + - Which tool did you use? + - Which hardware do you have? + - Was your tape unit online? + - Is it a shared tape unit? + +5. Send an email with your bug report to: + mailto:Linux390@de.ibm.com + + |