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Based on kernel version 3.16. Page generated on 2014-08-06 21:41 EST.

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 its 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 a file under /etc/modprobe.d/ directory.
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://sourceforge.net/projects/osst/
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
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