Blame view

kernel/linux-imx6_3.14.28/Documentation/blockdev/cciss.txt 7.3 KB
6b13f685e   김민수   BSP 최초 추가
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
  This driver is for Compaq's SMART Array Controllers.
  
  Supported Cards:
  ----------------
  
  This driver is known to work with the following cards:
  
  	* SA 5300
  	* SA 5i 
  	* SA 532
  	* SA 5312
  	* SA 641
  	* SA 642
  	* SA 6400
  	* SA 6400 U320 Expansion Module
  	* SA 6i
  	* SA P600
  	* SA P800
  	* SA E400
  	* SA P400i
  	* SA E200
  	* SA E200i
  	* SA E500
  	* SA P700m
  	* SA P212
  	* SA P410
  	* SA P410i
  	* SA P411
  	* SA P812
  	* SA P712m
  	* SA P711m
  
  Detecting drive failures:
  -------------------------
  
  To get the status of logical volumes and to detect physical drive
  failures, you can use the cciss_vol_status program found here:
  http://cciss.sourceforge.net/#cciss_utils
  
  Device Naming:
  --------------
  
  If nodes are not already created in the /dev/cciss directory, run as root:
  
  # cd /dev
  # ./MAKEDEV cciss
  
  You need some entries in /dev for the cciss device.  The MAKEDEV script
  can make device nodes for you automatically.  Currently the device setup
  is as follows:
  
  Major numbers:
  	104	cciss0	
  	105	cciss1	
  	106	cciss2
  	105	cciss3
  	108	cciss4
  	109	cciss5
  	110	cciss6
  	111	cciss7
  
  Minor numbers:
          b7 b6 b5 b4 b3 b2 b1 b0
          |----+----| |----+----|
               |           |
               |           +-------- Partition ID (0=wholedev, 1-15 partition)
               |
               +-------------------- Logical Volume number
  
  The device naming scheme is:
  /dev/cciss/c0d0			Controller 0, disk 0, whole device
  /dev/cciss/c0d0p1		Controller 0, disk 0, partition 1
  /dev/cciss/c0d0p2		Controller 0, disk 0, partition 2
  /dev/cciss/c0d0p3		Controller 0, disk 0, partition 3
  
  /dev/cciss/c1d1			Controller 1, disk 1, whole device
  /dev/cciss/c1d1p1		Controller 1, disk 1, partition 1
  /dev/cciss/c1d1p2		Controller 1, disk 1, partition 2
  /dev/cciss/c1d1p3		Controller 1, disk 1, partition 3
  
  CCISS simple mode support
  -------------------------
  
  The "cciss_simple_mode=1" boot parameter may be used to prevent the driver
  from putting the controller into "performant" mode. The difference is that
  with simple mode, each command completion requires an interrupt, while with
  "performant mode" (the default, and ordinarily better performing) it is
  possible to have multiple command completions indicated by a single
  interrupt.
  
  SCSI tape drive and medium changer support
  ------------------------------------------
  
  SCSI sequential access devices and medium changer devices are supported and 
  appropriate device nodes are automatically created.  (e.g.  
  /dev/st0, /dev/st1, etc.  See the "st" man page for more details.) 
  You must enable "SCSI tape drive support for Smart Array 5xxx" and 
  "SCSI support" in your kernel configuration to be able to use SCSI
  tape drives with your Smart Array 5xxx controller.
  
  Additionally, note that the driver will engage the SCSI core at init
  time if any tape drives or medium changers are detected.  The driver may
  also be directed to dynamically engage the SCSI core via the /proc filesystem
  entry which the "block" side of the driver creates as
  /proc/driver/cciss/cciss* at runtime.  This is best done via a script.
  
  For example:
  
  	for x in /proc/driver/cciss/cciss[0-9]*
  	do
  		echo "engage scsi" > $x
  	done
  
  Once the SCSI core is engaged by the driver, it cannot be disengaged 
  (except by unloading the driver, if it happens to be linked as a module.)
  
  Note also that if no sequential access devices or medium changers are
  detected, the SCSI core will not be engaged by the action of the above
  script.
  
  Hot plug support for SCSI tape drives
  -------------------------------------
  
  Hot plugging of SCSI tape drives is supported, with some caveats.
  The cciss driver must be informed that changes to the SCSI bus
  have been made.  This may be done via the /proc filesystem.
  For example:
  
  	echo "rescan" > /proc/scsi/cciss0/1
  
  This causes the driver to query the adapter about changes to the
  physical SCSI buses and/or fibre channel arbitrated loop and the
  driver to make note of any new or removed sequential access devices
  or medium changers.  The driver will output messages indicating what 
  devices have been added or removed and the controller, bus, target and 
  lun used to address the device.  It then notifies the SCSI mid layer
  of these changes.
  
  Note that the naming convention of the /proc filesystem entries 
  contains a number in addition to the driver name.  (E.g. "cciss0" 
  instead of just "cciss" which you might expect.)
  
  Note: ONLY sequential access devices and medium changers are presented 
  as SCSI devices to the SCSI mid layer by the cciss driver.  Specifically, 
  physical SCSI disk drives are NOT presented to the SCSI mid layer.  The 
  physical SCSI disk drives are controlled directly by the array controller 
  hardware and it is important to prevent the kernel from attempting to directly
  access these devices too, as if the array controller were merely a SCSI 
  controller in the same way that we are allowing it to access SCSI tape drives.
  
  SCSI error handling for tape drives and medium changers
  -------------------------------------------------------
  
  The linux SCSI mid layer provides an error handling protocol which
  kicks into gear whenever a SCSI command fails to complete within a
  certain amount of time (which can vary depending on the command).
  The cciss driver participates in this protocol to some extent.  The
  normal protocol is a four step process.  First the device is told
  to abort the command.  If that doesn't work, the device is reset.
  If that doesn't work, the SCSI bus is reset.  If that doesn't work
  the host bus adapter is reset.  Because the cciss driver is a block
  driver as well as a SCSI driver and only the tape drives and medium
  changers are presented to the SCSI mid layer, and unlike more 
  straightforward SCSI drivers, disk i/o continues through the block
  side during the SCSI error recovery process, the cciss driver only
  implements the first two of these actions, aborting the command, and
  resetting the device.  Additionally, most tape drives will not oblige 
  in aborting commands, and sometimes it appears they will not even 
  obey a reset command, though in most circumstances they will.  In
  the case that the command cannot be aborted and the device cannot be 
  reset, the device will be set offline.
  
  In the event the error handling code is triggered and a tape drive is
  successfully reset or the tardy command is successfully aborted, the 
  tape drive may still not allow i/o to continue until some command
  is issued which positions the tape to a known position.  Typically you
  must rewind the tape (by issuing "mt -f /dev/st0 rewind" for example)
  before i/o can proceed again to a tape drive which was reset.
  
  There is a cciss_tape_cmds module parameter which can be used to make cciss
  allocate more commands for use by tape drives.  Ordinarily only a few commands
  (6) are allocated for tape drives because tape drives are slow and
  infrequently used and the primary purpose of Smart Array controllers is to
  act as a RAID controller for disk drives, so the vast majority of commands
  are allocated for disk devices.  However, if you have more than a few tape
  drives attached to a smart array, the default number of commands may not be
  enought (for example, if you have 8 tape drives, you could only rewind 6
  at one time with the default number of commands.)  The cciss_tape_cmds module
  parameter allows more commands (up to 16 more) to be allocated for use by
  tape drives.  For example:
  
          insmod cciss.ko cciss_tape_cmds=16
  
  Or, as a kernel boot parameter passed in via grub:  cciss.cciss_tape_cmds=8