| 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 | |