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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/cciss.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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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
21If nodes are not already created in the /dev/cciss directory, run as root:
22
23# cd /dev
24# ./MAKEDEV cciss
25
26Device Naming:
27--------------
28
29You need some entries in /dev for the cciss device. The MAKEDEV script
30can make device nodes for you automatically. Currently the device setup
31is as follows:
32
33Major numbers:
34 104 cciss0
35 105 cciss1
36 106 cciss2
37 105 cciss3
38 108 cciss4
39 109 cciss5
40 110 cciss6
41 111 cciss7
42
43Minor numbers:
44 b7 b6 b5 b4 b3 b2 b1 b0
45 |----+----| |----+----|
46 | |
47 | +-------- Partition ID (0=wholedev, 1-15 partition)
48 |
49 +-------------------- Logical Volume number
50
51The device naming scheme is:
52/dev/cciss/c0d0 Controller 0, disk 0, whole device
53/dev/cciss/c0d0p1 Controller 0, disk 0, partition 1
54/dev/cciss/c0d0p2 Controller 0, disk 0, partition 2
55/dev/cciss/c0d0p3 Controller 0, disk 0, partition 3
56
57/dev/cciss/c1d1 Controller 1, disk 1, whole device
58/dev/cciss/c1d1p1 Controller 1, disk 1, partition 1
59/dev/cciss/c1d1p2 Controller 1, disk 1, partition 2
60/dev/cciss/c1d1p3 Controller 1, disk 1, partition 3
61
62SCSI tape drive and medium changer support
63------------------------------------------
64
65SCSI sequential access devices and medium changer devices are supported and
66appropriate device nodes are automatically created. (e.g.
67/dev/st0, /dev/st1, etc. See the "st" man page for more details.)
68You must enable "SCSI tape drive support for Smart Array 5xxx" and
69"SCSI support" in your kernel configuration to be able to use SCSI
70tape drives with your Smart Array 5xxx controller.
71
72Additionally, note that the driver will not engage the SCSI core at init
73time. The driver must be directed to dynamically engage the SCSI core via
74the /proc filesystem entry which the "block" side of the driver creates as
75/proc/driver/cciss/cciss* at runtime. This is because at driver init time,
76the SCSI core may not yet be initialized (because the driver is a block
77driver) and attempting to register it with the SCSI core in such a case
78would cause a hang. This is best done via an initialization script
79(typically in /etc/init.d, but could vary depending on distibution).
80For example:
81
82 for x in /proc/driver/cciss/cciss[0-9]*
83 do
84 echo "engage scsi" > $x
85 done
86
87Once the SCSI core is engaged by the driver, it cannot be disengaged
88(except by unloading the driver, if it happens to be linked as a module.)
89
90Note also that if no sequential access devices or medium changers are
91detected, the SCSI core will not be engaged by the action of the above
92script.
93
94Hot plug support for SCSI tape drives
95-------------------------------------
96
97Hot plugging of SCSI tape drives is supported, with some caveats.
98The cciss driver must be informed that changes to the SCSI bus
99have been made, in addition to and prior to informing the SCSI
100mid layer. This may be done via the /proc filesystem. For example:
101
102 echo "rescan" > /proc/scsi/cciss0/1
103
104This causes the adapter to query the adapter about changes to the
105physical SCSI buses and/or fibre channel arbitrated loop and the
106driver to make note of any new or removed sequential access devices
107or medium changers. The driver will output messages indicating what
108devices have been added or removed and the controller, bus, target and
109lun used to address the device. Once this is done, the SCSI mid layer
110can be informed of changes to the virtual SCSI bus which the driver
111presents to it in the usual way. For example:
112
113 echo scsi add-single-device 3 2 1 0 > /proc/scsi/scsi
114
115to add a device on controller 3, bus 2, target 1, lun 0. Note that
116the driver makes an effort to preserve the devices positions
117in the virtual SCSI bus, so if you are only moving tape drives
118around on the same adapter and not adding or removing tape drives
119from the adapter, informing the SCSI mid layer may not be necessary.
120
121Note that the naming convention of the /proc filesystem entries
122contains a number in addition to the driver name. (E.g. "cciss0"
123instead of just "cciss" which you might expect.)
124
125Note: ONLY sequential access devices and medium changers are presented
126as SCSI devices to the SCSI mid layer by the cciss driver. Specifically,
127physical SCSI disk drives are NOT presented to the SCSI mid layer. The
128physical SCSI disk drives are controlled directly by the array controller
129hardware and it is important to prevent the kernel from attempting to directly
130access these devices too, as if the array controller were merely a SCSI
131controller in the same way that we are allowing it to access SCSI tape drives.
132