1This driver is for Compaq's SMART Array Controllers.
2
3Supported Cards:
4----------------
5
6This driver is known to work with the following cards:
7
8	* SA 5300
9	* SA 5i 
10	* SA 532
11	* SA 5312
12	* SA 641
13	* SA 642
14	* SA 6400
15	* SA 6400 U320 Expansion Module
16	* SA 6i
17	* SA P600
18	* SA P800
19	* SA E400
20	* SA P400i
21	* SA E200
22	* SA E200i
23	* SA E500
24	* SA P700m
25	* SA P212
26	* SA P410
27	* SA P410i
28	* SA P411
29	* SA P812
30	* SA P712m
31	* SA P711m
32
33Detecting drive failures:
34-------------------------
35
36To get the status of logical volumes and to detect physical drive
37failures, you can use the cciss_vol_status program found here:
38http://cciss.sourceforge.net/#cciss_utils
39
40Device Naming:
41--------------
42
43If nodes are not already created in the /dev/cciss directory, run as root:
44
45# cd /dev
46# ./MAKEDEV cciss
47
48You need some entries in /dev for the cciss device.  The MAKEDEV script
49can make device nodes for you automatically.  Currently the device setup
50is as follows:
51
52Major numbers:
53	104	cciss0	
54	105	cciss1	
55	106	cciss2
56	105	cciss3
57	108	cciss4
58	109	cciss5
59	110	cciss6
60	111	cciss7
61
62Minor numbers:
63        b7 b6 b5 b4 b3 b2 b1 b0
64        |----+----| |----+----|
65             |           |
66             |           +-------- Partition ID (0=wholedev, 1-15 partition)
67             |
68             +-------------------- Logical Volume number
69
70The device naming scheme is:
71/dev/cciss/c0d0			Controller 0, disk 0, whole device
72/dev/cciss/c0d0p1		Controller 0, disk 0, partition 1
73/dev/cciss/c0d0p2		Controller 0, disk 0, partition 2
74/dev/cciss/c0d0p3		Controller 0, disk 0, partition 3
75
76/dev/cciss/c1d1			Controller 1, disk 1, whole device
77/dev/cciss/c1d1p1		Controller 1, disk 1, partition 1
78/dev/cciss/c1d1p2		Controller 1, disk 1, partition 2
79/dev/cciss/c1d1p3		Controller 1, disk 1, partition 3
80
81CCISS simple mode support
82-------------------------
83
84The "cciss_simple_mode=1" boot parameter may be used to prevent the driver
85from putting the controller into "performant" mode. The difference is that
86with simple mode, each command completion requires an interrupt, while with
87"performant mode" (the default, and ordinarily better performing) it is
88possible to have multiple command completions indicated by a single
89interrupt.
90
91SCSI tape drive and medium changer support
92------------------------------------------
93
94SCSI sequential access devices and medium changer devices are supported and 
95appropriate device nodes are automatically created.  (e.g.  
96/dev/st0, /dev/st1, etc.  See the "st" man page for more details.) 
97You must enable "SCSI tape drive support for Smart Array 5xxx" and 
98"SCSI support" in your kernel configuration to be able to use SCSI
99tape drives with your Smart Array 5xxx controller.
100
101Additionally, note that the driver will engage the SCSI core at init
102time if any tape drives or medium changers are detected.  The driver may
103also be directed to dynamically engage the SCSI core via the /proc filesystem
104entry which the "block" side of the driver creates as
105/proc/driver/cciss/cciss* at runtime.  This is best done via a script.
106
107For example:
108
109	for x in /proc/driver/cciss/cciss[0-9]*
110	do
111		echo "engage scsi" > $x
112	done
113
114Once the SCSI core is engaged by the driver, it cannot be disengaged 
115(except by unloading the driver, if it happens to be linked as a module.)
116
117Note also that if no sequential access devices or medium changers are
118detected, the SCSI core will not be engaged by the action of the above
119script.
120
121Hot plug support for SCSI tape drives
122-------------------------------------
123
124Hot plugging of SCSI tape drives is supported, with some caveats.
125The cciss driver must be informed that changes to the SCSI bus
126have been made.  This may be done via the /proc filesystem.
127For example:
128
129	echo "rescan" > /proc/scsi/cciss0/1
130
131This causes the driver to query the adapter about changes to the
132physical SCSI buses and/or fibre channel arbitrated loop and the
133driver to make note of any new or removed sequential access devices
134or medium changers.  The driver will output messages indicating what 
135devices have been added or removed and the controller, bus, target and 
136lun used to address the device.  It then notifies the SCSI mid layer
137of these changes.
138
139Note that the naming convention of the /proc filesystem entries 
140contains a number in addition to the driver name.  (E.g. "cciss0" 
141instead of just "cciss" which you might expect.)
142
143Note: ONLY sequential access devices and medium changers are presented 
144as SCSI devices to the SCSI mid layer by the cciss driver.  Specifically, 
145physical SCSI disk drives are NOT presented to the SCSI mid layer.  The 
146physical SCSI disk drives are controlled directly by the array controller 
147hardware and it is important to prevent the kernel from attempting to directly
148access these devices too, as if the array controller were merely a SCSI 
149controller in the same way that we are allowing it to access SCSI tape drives.
150
151SCSI error handling for tape drives and medium changers
152-------------------------------------------------------
153
154The linux SCSI mid layer provides an error handling protocol which
155kicks into gear whenever a SCSI command fails to complete within a
156certain amount of time (which can vary depending on the command).
157The cciss driver participates in this protocol to some extent.  The
158normal protocol is a four step process.  First the device is told
159to abort the command.  If that doesn't work, the device is reset.
160If that doesn't work, the SCSI bus is reset.  If that doesn't work
161the host bus adapter is reset.  Because the cciss driver is a block
162driver as well as a SCSI driver and only the tape drives and medium
163changers are presented to the SCSI mid layer, and unlike more 
164straightforward SCSI drivers, disk i/o continues through the block
165side during the SCSI error recovery process, the cciss driver only
166implements the first two of these actions, aborting the command, and
167resetting the device.  Additionally, most tape drives will not oblige 
168in aborting commands, and sometimes it appears they will not even 
169obey a reset command, though in most circumstances they will.  In
170the case that the command cannot be aborted and the device cannot be 
171reset, the device will be set offline.
172
173In the event the error handling code is triggered and a tape drive is
174successfully reset or the tardy command is successfully aborted, the 
175tape drive may still not allow i/o to continue until some command
176is issued which positions the tape to a known position.  Typically you
177must rewind the tape (by issuing "mt -f /dev/st0 rewind" for example)
178before i/o can proceed again to a tape drive which was reset.
179
180There is a cciss_tape_cmds module parameter which can be used to make cciss
181allocate more commands for use by tape drives.  Ordinarily only a few commands
182(6) are allocated for tape drives because tape drives are slow and
183infrequently used and the primary purpose of Smart Array controllers is to
184act as a RAID controller for disk drives, so the vast majority of commands
185are allocated for disk devices.  However, if you have more than a few tape
186drives attached to a smart array, the default number of commands may not be
187enought (for example, if you have 8 tape drives, you could only rewind 6
188at one time with the default number of commands.)  The cciss_tape_cmds module
189parameter allows more commands (up to 16 more) to be allocated for use by
190tape drives.  For example:
191
192        insmod cciss.ko cciss_tape_cmds=16
193
194Or, as a kernel boot parameter passed in via grub:  cciss.cciss_tape_cmds=8
195