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Linus Torvalds1da177e2005-04-16 15:20:36 -07001This 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
Mike Miller9dc7a862005-09-13 01:25:19 -070020 * SA P400i
21 * SA E200
22 * SA E200i
Mike Miller1883c5a2006-09-12 20:36:07 -070023 * SA E500
Linus Torvalds1da177e2005-04-16 15:20:36 -070024
25If nodes are not already created in the /dev/cciss directory, run as root:
26
27# cd /dev
28# ./MAKEDEV cciss
29
30Device Naming:
31--------------
32
33You need some entries in /dev for the cciss device. The MAKEDEV script
34can make device nodes for you automatically. Currently the device setup
35is as follows:
36
37Major numbers:
38 104 cciss0
39 105 cciss1
40 106 cciss2
41 105 cciss3
42 108 cciss4
43 109 cciss5
44 110 cciss6
45 111 cciss7
46
47Minor numbers:
48 b7 b6 b5 b4 b3 b2 b1 b0
49 |----+----| |----+----|
50 | |
51 | +-------- Partition ID (0=wholedev, 1-15 partition)
52 |
53 +-------------------- Logical Volume number
54
55The device naming scheme is:
56/dev/cciss/c0d0 Controller 0, disk 0, whole device
57/dev/cciss/c0d0p1 Controller 0, disk 0, partition 1
58/dev/cciss/c0d0p2 Controller 0, disk 0, partition 2
59/dev/cciss/c0d0p3 Controller 0, disk 0, partition 3
60
61/dev/cciss/c1d1 Controller 1, disk 1, whole device
62/dev/cciss/c1d1p1 Controller 1, disk 1, partition 1
63/dev/cciss/c1d1p2 Controller 1, disk 1, partition 2
64/dev/cciss/c1d1p3 Controller 1, disk 1, partition 3
65
66SCSI tape drive and medium changer support
67------------------------------------------
68
69SCSI sequential access devices and medium changer devices are supported and
70appropriate device nodes are automatically created. (e.g.
71/dev/st0, /dev/st1, etc. See the "st" man page for more details.)
72You must enable "SCSI tape drive support for Smart Array 5xxx" and
73"SCSI support" in your kernel configuration to be able to use SCSI
74tape drives with your Smart Array 5xxx controller.
75
76Additionally, note that the driver will not engage the SCSI core at init
77time. The driver must be directed to dynamically engage the SCSI core via
78the /proc filesystem entry which the "block" side of the driver creates as
79/proc/driver/cciss/cciss* at runtime. This is because at driver init time,
80the SCSI core may not yet be initialized (because the driver is a block
81driver) and attempting to register it with the SCSI core in such a case
82would cause a hang. This is best done via an initialization script
83(typically in /etc/init.d, but could vary depending on distibution).
84For example:
85
86 for x in /proc/driver/cciss/cciss[0-9]*
87 do
88 echo "engage scsi" > $x
89 done
90
91Once the SCSI core is engaged by the driver, it cannot be disengaged
92(except by unloading the driver, if it happens to be linked as a module.)
93
94Note also that if no sequential access devices or medium changers are
95detected, the SCSI core will not be engaged by the action of the above
96script.
97
98Hot plug support for SCSI tape drives
99-------------------------------------
100
101Hot plugging of SCSI tape drives is supported, with some caveats.
102The cciss driver must be informed that changes to the SCSI bus
103have been made, in addition to and prior to informing the SCSI
104mid layer. This may be done via the /proc filesystem. For example:
105
106 echo "rescan" > /proc/scsi/cciss0/1
107
108This causes the adapter to query the adapter about changes to the
109physical SCSI buses and/or fibre channel arbitrated loop and the
110driver to make note of any new or removed sequential access devices
111or medium changers. The driver will output messages indicating what
112devices have been added or removed and the controller, bus, target and
113lun used to address the device. Once this is done, the SCSI mid layer
114can be informed of changes to the virtual SCSI bus which the driver
115presents to it in the usual way. For example:
116
117 echo scsi add-single-device 3 2 1 0 > /proc/scsi/scsi
118
119to add a device on controller 3, bus 2, target 1, lun 0. Note that
120the driver makes an effort to preserve the devices positions
121in the virtual SCSI bus, so if you are only moving tape drives
122around on the same adapter and not adding or removing tape drives
123from the adapter, informing the SCSI mid layer may not be necessary.
124
125Note that the naming convention of the /proc filesystem entries
126contains a number in addition to the driver name. (E.g. "cciss0"
127instead of just "cciss" which you might expect.)
128
129Note: ONLY sequential access devices and medium changers are presented
130as SCSI devices to the SCSI mid layer by the cciss driver. Specifically,
131physical SCSI disk drives are NOT presented to the SCSI mid layer. The
132physical SCSI disk drives are controlled directly by the array controller
133hardware and it is important to prevent the kernel from attempting to directly
134access these devices too, as if the array controller were merely a SCSI
135controller in the same way that we are allowing it to access SCSI tape drives.
136
mike.miller@hp.com3da8b712005-11-04 12:30:37 -0600137SCSI error handling for tape drives and medium changers
138-------------------------------------------------------
139
140The linux SCSI mid layer provides an error handling protocol which
141kicks into gear whenever a SCSI command fails to complete within a
142certain amount of time (which can vary depending on the command).
143The cciss driver participates in this protocol to some extent. The
144normal protocol is a four step process. First the device is told
145to abort the command. If that doesn't work, the device is reset.
146If that doesn't work, the SCSI bus is reset. If that doesn't work
147the host bus adapter is reset. Because the cciss driver is a block
148driver as well as a SCSI driver and only the tape drives and medium
149changers are presented to the SCSI mid layer, and unlike more
150straightforward SCSI drivers, disk i/o continues through the block
151side during the SCSI error recovery process, the cciss driver only
152implements the first two of these actions, aborting the command, and
153resetting the device. Additionally, most tape drives will not oblige
154in aborting commands, and sometimes it appears they will not even
155obey a reset coommand, though in most circumstances they will. In
156the case that the command cannot be aborted and the device cannot be
157reset, the device will be set offline.
158
159In the event the error handling code is triggered and a tape drive is
160successfully reset or the tardy command is successfully aborted, the
161tape drive may still not allow i/o to continue until some command
162is issued which positions the tape to a known position. Typically you
163must rewind the tape (by issuing "mt -f /dev/st0 rewind" for example)
164before i/o can proceed again to a tape drive which was reset.
165