diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/scsi/osst.txt |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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1 | README file for the osst driver | ||
2 | =============================== | ||
3 | (w) Kurt Garloff <garloff@suse.de> 12/2000 | ||
4 | |||
5 | This file describes the osst driver as of version 0.8.x/0.9.x, the released | ||
6 | version of the osst driver. | ||
7 | It is intended to help advanced users to understand the role of osst and to | ||
8 | get them started using (and maybe debugging) it. | ||
9 | It won't address issues like "How do I compile a kernel?" or "How do I load | ||
10 | a module?", as these are too basic. | ||
11 | Once the OnStream got merged into the official kernel, the distro makers | ||
12 | will provide the OnStream support for those who are not familiar with | ||
13 | hacking their kernels. | ||
14 | |||
15 | |||
16 | Purpose | ||
17 | ------- | ||
18 | The osst driver was developed, because the standard SCSI tape driver in | ||
19 | Linux, st, does not support the OnStream SC-x0 SCSI tape. The st is not to | ||
20 | blame for that, as the OnStream tape drives do not support the standard SCSI | ||
21 | command set for Serial Access Storage Devices (SASDs), which basically | ||
22 | corresponds to the QIC-157 spec. | ||
23 | Nevertheless, the OnStream tapes are nice pieces of hardware and therefore | ||
24 | the osst driver has been written to make these tape devs supported by Linux. | ||
25 | The driver is free software. It's released under the GNU GPL and planned to | ||
26 | be integrated into the mainstream kernel. | ||
27 | |||
28 | |||
29 | Implementation | ||
30 | -------------- | ||
31 | The osst is a new high-level SCSI driver, just like st, sr, sd and sg. It | ||
32 | can be compiled into the kernel or loaded as a module. | ||
33 | As it represents a new device, it got assigned a new device node: /dev/osstX | ||
34 | are character devices with major no 206 and minor numbers like the /dev/stX | ||
35 | devices. If those are not present, you may create them by calling | ||
36 | Makedevs.sh as root (see below). | ||
37 | The driver started being a copy of st and as such, the osst devices' | ||
38 | behavior looks very much the same as st to the userspace applications. | ||
39 | |||
40 | |||
41 | History | ||
42 | ------- | ||
43 | In the first place, osst shared it's identity very much with st. That meant | ||
44 | that it used the same kernel structures and the same device node as st. | ||
45 | So you could only have either of them being present in the kernel. This has | ||
46 | been fixed by registering an own device, now. | ||
47 | st and osst can coexist, each only accessing the devices it can support by | ||
48 | themselves. | ||
49 | |||
50 | |||
51 | Installation | ||
52 | ------------ | ||
53 | osst got integrated into the linux kernel. Select it during kernel | ||
54 | configuration as module or compile statically into the kernel. | ||
55 | Compile your kernel and install the modules. | ||
56 | |||
57 | Now, your osst driver is inside the kernel or available as a module, | ||
58 | depending on your choice during kernel config. You may still need to create | ||
59 | the device nodes by calling the Makedevs.sh script (see below) manually, | ||
60 | unless you use a devfs kernel, where this won't be needed. | ||
61 | |||
62 | To load your module, you may use the command | ||
63 | modprobe osst | ||
64 | as root. dmesg should show you, whether your OnStream tapes have been | ||
65 | recognized. | ||
66 | |||
67 | If you want to have the module autoloaded on access to /dev/osst, you may | ||
68 | add something like | ||
69 | alias char-major-206 osst | ||
70 | to your /etc/modprobe.conf (before 2.6: modules.conf). | ||
71 | |||
72 | You may find it convenient to create a symbolic link | ||
73 | ln -s nosst0 /dev/tape | ||
74 | to make programs assuming a default name of /dev/tape more convenient to | ||
75 | use. | ||
76 | |||
77 | The device nodes for osst have to be created. Use the Makedevs.sh script | ||
78 | attached to this file. | ||
79 | |||
80 | |||
81 | Using it | ||
82 | -------- | ||
83 | You may use the OnStream tape driver with your standard backup software, | ||
84 | which may be tar, cpio, amanda, arkeia, BRU, Lone Tar, ... | ||
85 | by specifying /dev/(n)osst0 as the tape device to use or using the above | ||
86 | symlink trick. The IOCTLs to control tape operation are also mostly | ||
87 | supported and you may try the mt (or mt_st) program to jump between | ||
88 | filemarks, eject the tape, ... | ||
89 | |||
90 | There's one limitation: You need to use a block size of 32kB. | ||
91 | |||
92 | (This limitation is worked on and will be fixed in version 0.8.8 of | ||
93 | this driver.) | ||
94 | |||
95 | If you just want to get started with standard software, here is an example | ||
96 | for creating and restoring a full backup: | ||
97 | # Backup | ||
98 | tar cvf - / --exclude /proc | buffer -s 32k -m 24M -B -t -o /dev/nosst0 | ||
99 | # Restore | ||
100 | buffer -s 32k -m 8M -B -t -i /dev/osst0 | tar xvf - -C / | ||
101 | |||
102 | The buffer command has been used to buffer the data before it goes to the | ||
103 | tape (or the file system) in order to smooth out the data stream and prevent | ||
104 | the tape from needing to stop and rewind. The OnStream does have an internal | ||
105 | buffer and a variable speed which help this, but especially on writing, the | ||
106 | buffering still proves useful in most cases. It also pads the data to | ||
107 | guarantees the block size of 32k. (Otherwise you may pass the -b64 option to | ||
108 | tar.) | ||
109 | Expect something like 1.8MB/s for the SC-x0 drives and 0.9MB/s for the DI-30. | ||
110 | The USB drive will give you about 0.7MB/s. | ||
111 | On a fast machine, you may profit from software data compression (z flag for | ||
112 | tar). | ||
113 | |||
114 | |||
115 | USB and IDE | ||
116 | ----------- | ||
117 | Via the SCSI emulation layers usb-storage and ide-scsi, you can also use the | ||
118 | osst driver to drive the USB-30 and the DI-30 drives. (Unfortunately, there | ||
119 | is no such layer for the parallel port, otherwise the DP-30 would work as | ||
120 | well.) For the USB support, you need the latest 2.4.0-test kernels and the | ||
121 | latest usb-storage driver from | ||
122 | http://www.linux-usb.org/ | ||
123 | http://sourceforge.net/cvs/?group_id=3581 | ||
124 | |||
125 | Note that the ide-tape driver as of 1.16f uses a slightly outdated on-tape | ||
126 | format and therefore is not completely interoperable with osst tapes. | ||
127 | |||
128 | The ADR-x0 line is fully SCSI-2 compliant and is supported by st, not osst. | ||
129 | The on-tape format is supposed to be compatible with the one used by osst. | ||
130 | |||
131 | |||
132 | Feedback and updates | ||
133 | -------------------- | ||
134 | The driver development is coordinated through a mailing list | ||
135 | <osst@linux1.onstream.nl> | ||
136 | a CVS repository and some web pages. | ||
137 | The tester's pages which contain recent news and updated drivers to download | ||
138 | can be found on | ||
139 | http://linux1.onstream.nl/test/ | ||
140 | |||
141 | If you find any problems, please have a look at the tester's page in order | ||
142 | to see whether the problem is already known and solved. Otherwise, please | ||
143 | report it to the mailing list. Your feedback is welcome. (This holds also | ||
144 | for reports of successful usage, of course.) | ||
145 | In case of trouble, please do always provide the following info: | ||
146 | * driver and kernel version used (see syslog) | ||
147 | * driver messages (syslog) | ||
148 | * SCSI config and OnStream Firmware (/proc/scsi/scsi) | ||
149 | * description of error. Is it reproducible? | ||
150 | * software and commands used | ||
151 | |||
152 | You may subscribe to the mailing list, BTW, it's a majordomo list. | ||
153 | |||
154 | |||
155 | Status | ||
156 | ------ | ||
157 | 0.8.0 was the first widespread BETA release. Since then a lot of reports | ||
158 | have been sent, but mostly reported success or only minor trouble. | ||
159 | All the issues have been addressed. | ||
160 | Check the web pages for more info about the current developments. | ||
161 | 0.9.x is the tree for the 2.3/2.4 kernel. | ||
162 | |||
163 | |||
164 | Acknowledgments | ||
165 | ---------------- | ||
166 | The driver has been started by making a copy of Kai Makisara's st driver. | ||
167 | Most of the development has been done by Willem Riede. The presence of the | ||
168 | userspace program osg (onstreamsg) from Terry Hardie has been rather | ||
169 | helpful. The same holds for Gadi Oxman's ide-tape support for the DI-30. | ||
170 | I did add some patches to those drivers as well and coordinated things a | ||
171 | little bit. | ||
172 | Note that most of them did mostly spend their spare time for the creation of | ||
173 | this driver. | ||
174 | The people from OnStream, especially Jack Bombeeck did support this project | ||
175 | and always tried to answer HW or FW related questions. Furthermore, he | ||
176 | pushed the FW developers to do the right things. | ||
177 | SuSE did support this project by allowing me to work on it during my working | ||
178 | time for them and by integrating the driver into their distro. | ||
179 | |||
180 | More people did help by sending useful comments. Sorry to those who have | ||
181 | been forgotten. Thanks to all the GNU/FSF and Linux developers who made this | ||
182 | platform such an interesting, nice and stable platform. | ||
183 | Thanks go to those who tested the drivers and did send useful reports. Your | ||
184 | help is needed! | ||
185 | |||
186 | |||
187 | Makedevs.sh | ||
188 | ----------- | ||
189 | #!/bin/sh | ||
190 | # Script to create OnStream SC-x0 device nodes (major 206) | ||
191 | # Usage: Makedevs.sh [nos [path to dev]] | ||
192 | # $Id: README.osst.kernel,v 1.4 2000/12/20 14:13:15 garloff Exp $ | ||
193 | major=206 | ||
194 | nrs=4 | ||
195 | dir=/dev | ||
196 | test -z "$1" || nrs=$1 | ||
197 | test -z "$2" || dir=$2 | ||
198 | declare -i nr | ||
199 | nr=0 | ||
200 | test -d $dir || mkdir -p $dir | ||
201 | while test $nr -lt $nrs; do | ||
202 | mknod $dir/osst$nr c $major $nr | ||
203 | chown 0.disk $dir/osst$nr; chmod 660 $dir/osst$nr; | ||
204 | mknod $dir/nosst$nr c $major $[nr+128] | ||
205 | chown 0.disk $dir/nosst$nr; chmod 660 $dir/nosst$nr; | ||
206 | mknod $dir/osst${nr}l c $major $[nr+32] | ||
207 | chown 0.disk $dir/osst${nr}l; chmod 660 $dir/osst${nr}l; | ||
208 | mknod $dir/nosst${nr}l c $major $[nr+160] | ||
209 | chown 0.disk $dir/nosst${nr}l; chmod 660 $dir/nosst${nr}l; | ||
210 | mknod $dir/osst${nr}m c $major $[nr+64] | ||
211 | chown 0.disk $dir/osst${nr}m; chmod 660 $dir/osst${nr}m; | ||
212 | mknod $dir/nosst${nr}m c $major $[nr+192] | ||
213 | chown 0.disk $dir/nosst${nr}m; chmod 660 $dir/nosst${nr}m; | ||
214 | mknod $dir/osst${nr}a c $major $[nr+96] | ||
215 | chown 0.disk $dir/osst${nr}a; chmod 660 $dir/osst${nr}a; | ||
216 | mknod $dir/nosst${nr}a c $major $[nr+224] | ||
217 | chown 0.disk $dir/nosst${nr}a; chmod 660 $dir/nosst${nr}a; | ||
218 | let nr+=1 | ||
219 | done | ||