1 This driver is for Compaq's SMART Array Controllers.
6 This driver is known to work with the following cards:
15 * SA 6400 U320 Expansion Module
30 Detecting drive failures:
31 -------------------------
33 To get the status of logical volumes and to detect physical drive
34 failures, you can use the cciss_vol_status program found here:
35 http://cciss.sourceforge.net/#cciss_utils
40 If nodes are not already created in the /dev/cciss directory, run as root:
45 You need some entries in /dev for the cciss device. The MAKEDEV script
46 can make device nodes for you automatically. Currently the device setup
60 b7 b6 b5 b4 b3 b2 b1 b0
61 |----+----| |----+----|
63 | +-------- Partition ID (0=wholedev, 1-15 partition)
65 +-------------------- Logical Volume number
67 The device naming scheme is:
68 /dev/cciss/c0d0 Controller 0, disk 0, whole device
69 /dev/cciss/c0d0p1 Controller 0, disk 0, partition 1
70 /dev/cciss/c0d0p2 Controller 0, disk 0, partition 2
71 /dev/cciss/c0d0p3 Controller 0, disk 0, partition 3
73 /dev/cciss/c1d1 Controller 1, disk 1, whole device
74 /dev/cciss/c1d1p1 Controller 1, disk 1, partition 1
75 /dev/cciss/c1d1p2 Controller 1, disk 1, partition 2
76 /dev/cciss/c1d1p3 Controller 1, disk 1, partition 3
78 SCSI tape drive and medium changer support
79 ------------------------------------------
81 SCSI sequential access devices and medium changer devices are supported and
82 appropriate device nodes are automatically created. (e.g.
83 /dev/st0, /dev/st1, etc. See the "st" man page for more details.)
84 You must enable "SCSI tape drive support for Smart Array 5xxx" and
85 "SCSI support" in your kernel configuration to be able to use SCSI
86 tape drives with your Smart Array 5xxx controller.
88 Additionally, note that the driver will not engage the SCSI core at init
89 time. The driver must be directed to dynamically engage the SCSI core via
90 the /proc filesystem entry which the "block" side of the driver creates as
91 /proc/driver/cciss/cciss* at runtime. This is because at driver init time,
92 the SCSI core may not yet be initialized (because the driver is a block
93 driver) and attempting to register it with the SCSI core in such a case
94 would cause a hang. This is best done via an initialization script
95 (typically in /etc/init.d, but could vary depending on distribution).
98 for x in /proc/driver/cciss/cciss[0-9]*
100 echo "engage scsi" > $x
103 Once the SCSI core is engaged by the driver, it cannot be disengaged
104 (except by unloading the driver, if it happens to be linked as a module.)
106 Note also that if no sequential access devices or medium changers are
107 detected, the SCSI core will not be engaged by the action of the above
110 Hot plug support for SCSI tape drives
111 -------------------------------------
113 Hot plugging of SCSI tape drives is supported, with some caveats.
114 The cciss driver must be informed that changes to the SCSI bus
115 have been made, in addition to and prior to informing the SCSI
116 mid layer. This may be done via the /proc filesystem. For example:
118 echo "rescan" > /proc/scsi/cciss0/1
120 This causes the adapter to query the adapter about changes to the
121 physical SCSI buses and/or fibre channel arbitrated loop and the
122 driver to make note of any new or removed sequential access devices
123 or medium changers. The driver will output messages indicating what
124 devices have been added or removed and the controller, bus, target and
125 lun used to address the device. Once this is done, the SCSI mid layer
126 can be informed of changes to the virtual SCSI bus which the driver
127 presents to it in the usual way. For example:
129 echo scsi add-single-device 3 2 1 0 > /proc/scsi/scsi
131 to add a device on controller 3, bus 2, target 1, lun 0. Note that
132 the driver makes an effort to preserve the devices positions
133 in the virtual SCSI bus, so if you are only moving tape drives
134 around on the same adapter and not adding or removing tape drives
135 from the adapter, informing the SCSI mid layer may not be necessary.
137 Note that the naming convention of the /proc filesystem entries
138 contains a number in addition to the driver name. (E.g. "cciss0"
139 instead of just "cciss" which you might expect.)
141 Note: ONLY sequential access devices and medium changers are presented
142 as SCSI devices to the SCSI mid layer by the cciss driver. Specifically,
143 physical SCSI disk drives are NOT presented to the SCSI mid layer. The
144 physical SCSI disk drives are controlled directly by the array controller
145 hardware and it is important to prevent the kernel from attempting to directly
146 access these devices too, as if the array controller were merely a SCSI
147 controller in the same way that we are allowing it to access SCSI tape drives.
149 SCSI error handling for tape drives and medium changers
150 -------------------------------------------------------
152 The linux SCSI mid layer provides an error handling protocol which
153 kicks into gear whenever a SCSI command fails to complete within a
154 certain amount of time (which can vary depending on the command).
155 The cciss driver participates in this protocol to some extent. The
156 normal protocol is a four step process. First the device is told
157 to abort the command. If that doesn't work, the device is reset.
158 If that doesn't work, the SCSI bus is reset. If that doesn't work
159 the host bus adapter is reset. Because the cciss driver is a block
160 driver as well as a SCSI driver and only the tape drives and medium
161 changers are presented to the SCSI mid layer, and unlike more
162 straightforward SCSI drivers, disk i/o continues through the block
163 side during the SCSI error recovery process, the cciss driver only
164 implements the first two of these actions, aborting the command, and
165 resetting the device. Additionally, most tape drives will not oblige
166 in aborting commands, and sometimes it appears they will not even
167 obey a reset command, though in most circumstances they will. In
168 the case that the command cannot be aborted and the device cannot be
169 reset, the device will be set offline.
171 In the event the error handling code is triggered and a tape drive is
172 successfully reset or the tardy command is successfully aborted, the
173 tape drive may still not allow i/o to continue until some command
174 is issued which positions the tape to a known position. Typically you
175 must rewind the tape (by issuing "mt -f /dev/st0 rewind" for example)
176 before i/o can proceed again to a tape drive which was reset.