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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

If nodes are not already created in the /dev/cciss directory

# mkdev.cciss [ctlrs]

Where ctlrs is the number of controllers you have (defaults to 1 if not

specified).

Device Naming:

--------------

You need some entries in /dev for the cciss device.  The mkdev.cciss script

can make device nodes for you automatically.  Currently the device setup

is as follows:

Major numbers:

        104     cciss0

        105     cciss1

        106     cciss2

        etc...

Minor numbers:

        b7 b6 b5 b4 b3 b2 b1 b0

        |----+----| |----+----|

             |           |

             |           +-------- Partition ID (0=wholedev, 1-15 partition)

             |

             +-------------------- Logical Volume number

The suggested 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

Support for more than 8 controllers

-----------------------------------

Originally the driver only supports 8 controllers in the system,

and this is due to the major numbers assigned to the driver

(104 thru 111).

The driver can now support up to 32 controllers in the system.

For the ninth controller and beyond, the major numbers will be

assigned dynamically by the kernel when it is discovered,

and there is no guarantee what the major number you will get,

but most likely it will start from 254 and goes down from there.

You can check the assigned major numbers by typing

        cat /proc/devices

And look for cciss controllers

Once you have this, you need to create device nodes in

/dev/cciss directory. The nodes for the first 8 controllers

should already be created by mkdev.cciss script or

/etc/makedev.d/cciss script. You can add the major number(s)

in those scripts, or create the nodes manually by using

the mknod command.

You can also use mknod_dyn.cciss and rmnod_dyn.cciss scripts

to create or remove nodes easily. These scripts can be found

in the Documentation directory.

Then you can mount the devices and create partitions

(You also need to make nodes for these partitions).

As for the minor number, the disk device will have a minor

number divisible by 16 (e.g: 0, 16, 32 etc), and the

partitions on those disk devices will have the minor number

of the disk device plus the partition number (1-15).

For example, disk d2 will have minor number 32, and its

partitions 1 and 2 will have minor numbers 33 and 34.

Look at the mkdev.cciss script for example.

Note:

 In 2.4 kernel, partition names are hard coded in

 /usr/src/linux/fs/partitions/check.c

 and only for the first 8 cciss controllers. The rest

 will be reported as ccissXX. This should not affect

 I/O operation or performance. Please apply the

 cciss_2.4_partition_name.patch to address this. This

 will not be an issue under 2.5 kernel, since partition

 names will be handled by the driver.

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 not engage the SCSI core at init

time.  The driver must 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 because at driver init time,

the SCSI core may not yet be initialized (because the driver is a block

driver) and attempting to register it with the SCSI core in such a case

would cause a hang.  This is best done via an initialization script

(typically in /etc/init.d, but could vary depending on distibution).

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, in addition to and prior to informing the SCSI

mid layer.  This may be done via the /proc filesystem.  For example:

        echo "rescan" > /proc/scsi/cciss0/1

This causes the adapter 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.  Once this is done, the SCSI mid layer

can be informed of changes to the virtual SCSI bus which the driver

presents to it in the usual way. For example:

        echo scsi add-single-device 3 2 1 0 > /proc/scsi/scsi

to add a device on controller 3, bus 2, target 1, lun 0.   Note that

the driver makes an effort to preserve the devices positions

in the virtual SCSI bus, so if you are only moving tape drives

around on the same adapter and not adding or removing tape drives

from the adapter, informing the SCSI mid layer may not be necessary.

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.)   This is because

of changes to the 2.4 kernel PCI interface related to PCI hot plug

that imply the driver must register with the SCSI mid layer once per

adapter instance rather than once per driver.

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 OS 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.

Monitor Threads

---------------

For multipath configurations (acheived via a higher level driver, such

as the "md" driver) it is important that failure of a controller is detected.

Ordinarily, the driver is entirely interrupt driven.  If a failure occurs

in such a way that the processor cannot receive interrupts from an adapter,

the driver will wait forever for i/o's to complete.  In a multipath

configuration this is undesirable, as the md driver relies on i/o's being

reported as failed by the low level driver to trigger failing over to an

alternate controller.  The monitor threads allow the driver to detect such

situations and report outstanding i/o's as having failed so that recovery

actions such switching to an alternate controller can occur.  The monitor

threads periodically sends a trivial "no-operation" command down to

the controllers and expect them to complete within a a reasonable (short)

time period.  The firmware on the adapter is designed such that no matter

how busy the adapter is serving i/o, it can respond quickly to a

"no-operation" command.  In the event that a deadline elapses before a no

operation command completes, all outstanding commands on that controller

are reported back to the upper layers as having failed, and any new commands

sent to the controller are immediately reported back as failed.

To enable the monitor threads, the compile time option must be enabled

(via the usual linux kernel configuration) and the monitor thread must

be enabled at runtime as well.  A system may have many adapters, but

perhaps only a single pair operating in a multipath configuration.

In this way, it is possible to run monitoring threads only for those

adapters which require it.

To start a monitoring thread on the first cciss adapter, "cciss0" with

a polling interval of 30 seconds, execute the following command:

        echo "monitor 30" > /proc/driver/cciss/cciss0

To change the polling interval, to say, 60 seconds:

        echo "monitor 60" > /proc/driver/cciss/cciss0

(Note, the change will not take effect until the previous polling

interval elapses.)

To disable the monitoring thread, set the polling interval to 0 seconds:

        echo "monitor 0" > /proc/driver/cciss/cciss0

(Again, the monitoring thread will not exit until the previous polling

interval elapses.)

The minimum monitoring period is 10 seconds, and the maximum monitoring

period is 3600 seconds (1 hour).  The no-operation command must complete

with 5 seconds of submission in all cases or the controller will be presumed

failed.