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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 | |
61 | To load your module, you may use the command |
62 | modprobe osst |
63 | as root. dmesg should show you, whether your OnStream tapes have been |
64 | recognized. |
65 | |
66 | If you want to have the module autoloaded on access to /dev/osst, you may |
67 | add something like |
68 | alias char-major-206 osst |
69 | to your /etc/modprobe.conf (before 2.6: modules.conf). |
70 | |
71 | You may find it convenient to create a symbolic link |
72 | ln -s nosst0 /dev/tape |
73 | to make programs assuming a default name of /dev/tape more convenient to |
74 | use. |
75 | |
76 | The device nodes for osst have to be created. Use the Makedevs.sh script |
77 | attached to this file. |
78 | |
79 | |
80 | Using it |
81 | -------- |
82 | You may use the OnStream tape driver with your standard backup software, |
83 | which may be tar, cpio, amanda, arkeia, BRU, Lone Tar, ... |
84 | by specifying /dev/(n)osst0 as the tape device to use or using the above |
85 | symlink trick. The IOCTLs to control tape operation are also mostly |
86 | supported and you may try the mt (or mt_st) program to jump between |
87 | filemarks, eject the tape, ... |
88 | |
89 | There's one limitation: You need to use a block size of 32kB. |
90 | |
91 | (This limitation is worked on and will be fixed in version 0.8.8 of |
92 | this driver.) |
93 | |
94 | If you just want to get started with standard software, here is an example |
95 | for creating and restoring a full backup: |
96 | # Backup |
97 | tar cvf - / --exclude /proc | buffer -s 32k -m 24M -B -t -o /dev/nosst0 |
98 | # Restore |
99 | buffer -s 32k -m 8M -B -t -i /dev/osst0 | tar xvf - -C / |
100 | |
101 | The buffer command has been used to buffer the data before it goes to the |
102 | tape (or the file system) in order to smooth out the data stream and prevent |
103 | the tape from needing to stop and rewind. The OnStream does have an internal |
104 | buffer and a variable speed which help this, but especially on writing, the |
105 | buffering still proves useful in most cases. It also pads the data to |
106 | guarantees the block size of 32k. (Otherwise you may pass the -b64 option to |
107 | tar.) |
108 | Expect something like 1.8MB/s for the SC-x0 drives and 0.9MB/s for the DI-30. |
109 | The USB drive will give you about 0.7MB/s. |
110 | On a fast machine, you may profit from software data compression (z flag for |
111 | tar). |
112 | |
113 | |
114 | USB and IDE |
115 | ----------- |
116 | Via the SCSI emulation layers usb-storage and ide-scsi, you can also use the |
117 | osst driver to drive the USB-30 and the DI-30 drives. (Unfortunately, there |
118 | is no such layer for the parallel port, otherwise the DP-30 would work as |
119 | well.) For the USB support, you need the latest 2.4.0-test kernels and the |
120 | latest usb-storage driver from |
121 | http://www.linux-usb.org/ |
122 | http://sourceforge.net/cvs/?group_id=3581 |
123 | |
124 | Note that the ide-tape driver as of 1.16f uses a slightly outdated on-tape |
125 | format and therefore is not completely interoperable with osst tapes. |
126 | |
127 | The ADR-x0 line is fully SCSI-2 compliant and is supported by st, not osst. |
128 | The on-tape format is supposed to be compatible with the one used by osst. |
129 | |
130 | |
131 | Feedback and updates |
132 | -------------------- |
133 | The driver development is coordinated through a mailing list |
134 | <osst@linux1.onstream.nl> |
135 | a CVS repository and some web pages. |
136 | The tester's pages which contain recent news and updated drivers to download |
137 | can be found on |
138 | http://linux1.onstream.nl/test/ |
139 | |
140 | If you find any problems, please have a look at the tester's page in order |
141 | to see whether the problem is already known and solved. Otherwise, please |
142 | report it to the mailing list. Your feedback is welcome. (This holds also |
143 | for reports of successful usage, of course.) |
144 | In case of trouble, please do always provide the following info: |
145 | * driver and kernel version used (see syslog) |
146 | * driver messages (syslog) |
147 | * SCSI config and OnStream Firmware (/proc/scsi/scsi) |
148 | * description of error. Is it reproducible? |
149 | * software and commands used |
150 | |
151 | You may subscribe to the mailing list, BTW, it's a majordomo list. |
152 | |
153 | |
154 | Status |
155 | ------ |
156 | 0.8.0 was the first widespread BETA release. Since then a lot of reports |
157 | have been sent, but mostly reported success or only minor trouble. |
158 | All the issues have been addressed. |
159 | Check the web pages for more info about the current developments. |
160 | 0.9.x is the tree for the 2.3/2.4 kernel. |
161 | |
162 | |
163 | Acknowledgments |
164 | ---------------- |
165 | The driver has been started by making a copy of Kai Makisara's st driver. |
166 | Most of the development has been done by Willem Riede. The presence of the |
167 | userspace program osg (onstreamsg) from Terry Hardie has been rather |
168 | helpful. The same holds for Gadi Oxman's ide-tape support for the DI-30. |
169 | I did add some patches to those drivers as well and coordinated things a |
170 | little bit. |
171 | Note that most of them did mostly spend their spare time for the creation of |
172 | this driver. |
173 | The people from OnStream, especially Jack Bombeeck did support this project |
174 | and always tried to answer HW or FW related questions. Furthermore, he |
175 | pushed the FW developers to do the right things. |
176 | SuSE did support this project by allowing me to work on it during my working |
177 | time for them and by integrating the driver into their distro. |
178 | |
179 | More people did help by sending useful comments. Sorry to those who have |
180 | been forgotten. Thanks to all the GNU/FSF and Linux developers who made this |
181 | platform such an interesting, nice and stable platform. |
182 | Thanks go to those who tested the drivers and did send useful reports. Your |
183 | help is needed! |
184 | |
185 | |
186 | Makedevs.sh |
187 | ----------- |
188 | #!/bin/sh |
189 | # Script to create OnStream SC-x0 device nodes (major 206) |
190 | # Usage: Makedevs.sh [nos [path to dev]] |
191 | # $Id: README.osst.kernel,v 1.4 2000/12/20 14:13:15 garloff Exp $ |
192 | major=206 |
193 | nrs=4 |
194 | dir=/dev |
195 | test -z "$1" || nrs=$1 |
196 | test -z "$2" || dir=$2 |
197 | declare -i nr |
198 | nr=0 |
199 | test -d $dir || mkdir -p $dir |
200 | while test $nr -lt $nrs; do |
201 | mknod $dir/osst$nr c $major $nr |
202 | chown 0.disk $dir/osst$nr; chmod 660 $dir/osst$nr; |
203 | mknod $dir/nosst$nr c $major $[nr+128] |
204 | chown 0.disk $dir/nosst$nr; chmod 660 $dir/nosst$nr; |
205 | mknod $dir/osst${nr}l c $major $[nr+32] |
206 | chown 0.disk $dir/osst${nr}l; chmod 660 $dir/osst${nr}l; |
207 | mknod $dir/nosst${nr}l c $major $[nr+160] |
208 | chown 0.disk $dir/nosst${nr}l; chmod 660 $dir/nosst${nr}l; |
209 | mknod $dir/osst${nr}m c $major $[nr+64] |
210 | chown 0.disk $dir/osst${nr}m; chmod 660 $dir/osst${nr}m; |
211 | mknod $dir/nosst${nr}m c $major $[nr+192] |
212 | chown 0.disk $dir/nosst${nr}m; chmod 660 $dir/nosst${nr}m; |
213 | mknod $dir/osst${nr}a c $major $[nr+96] |
214 | chown 0.disk $dir/osst${nr}a; chmod 660 $dir/osst${nr}a; |
215 | mknod $dir/nosst${nr}a c $major $[nr+224] |
216 | chown 0.disk $dir/nosst${nr}a; chmod 660 $dir/nosst${nr}a; |
217 | let nr+=1 |
218 | done |
219 |
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