Codex

CCISS

Section: Linux Programmer's Manual (4)

Updated: 2012-08-05

Index?action=index Return to Main Contents


NAME

cciss - HP Smart Array block driver

SYNOPSIS

DESCRIPTION

cciss is a block driver for older HP Smart Array RAID controllers.

Options

cciss_allow_hpsa=1: This option prevents the cciss driver from attempting to drive any controllers that the hpsa?(4) driver is capable of controlling, which is to say, the cciss driver is restricted by this option to the following controllers:

Supported hardware

The cciss driver supports the following Smart Array boards:

Configuration details

To configure HP Smart Array controllers, use the HP Array Configuration Utility (either hpacuxe?(8) or hpacucli?(8)) or the Offline ROM-based Configuration Utility (ORCA) run from the Smart Array's option ROM at boot time.

FILES

Device nodes

The device naming scheme is as follows:

Files in /proc

The files /proc/driver/cciss/cciss[0-9]+ contain information about the configuration of each controller. For example:

$ cd /proc/driver/cciss $ ls -l total 0 -rw-r--r-- 1 root root 0 2010-09-10 10:38 cciss0 -rw-r--r-- 1 root root 0 2010-09-10 10:38 cciss1 -rw-r--r-- 1 root root 0 2010-09-10 10:38 cciss2 $ cat cciss2 cciss2: HP Smart Array P800 Controller Board ID: 0x3223103c Firmware Version: 7.14 IRQ: 16 Logical drives: 1 Current Q depth: 0 Current # commands on controller: 0 Max Q depth since init: 1 Max # commands on controller since init: 2 Max SG entries since init: 32 Sequential access devices: 0

cciss/c2d0: 36.38GB RAID 0

@]

Files in /sys

/sys/bus/pci/devices/<dev>/ccissX/cXdY/model
Displays the SCSI INQUIRY page 0 model for logical drive Y of controller X.:
/sys/bus/pci/devices/<dev>/ccissX/cXdY/rev
Displays the SCSI INQUIRY page 0 revision for logical drive Y of controller X.:
/sys/bus/pci/devices/<dev>/ccissX/cXdY/unique_id
Displays the SCSI INQUIRY page 83 serial number for logical drive Y of controller X.:
/sys/bus/pci/devices/<dev>/ccissX/cXdY/vendor
Displays the SCSI INQUIRY page 0 vendor for logical drive Y of controller X.:
/sys/bus/pci/devices/<dev>/ccissX/cXdY/block
cciss!cXdY:A symbolic link to /sys/block/cciss!cXdY.:
/sys/bus/pci/devices/<dev>/ccissX/rescan
When this file is written to, the driver rescans the controller to discover any new, removed, or modified logical drives.:
/sys/bus/pci/devices/<dev>/ccissX/resettable
A value of 1 displayed in this file indicates that the "reset_devices=1" kernel parameter (used by kdump) is honored by this controller. A value of 0 indicates that the "reset_devices=1" kernel parameter will not be honored. Some models of Smart Array are not able to honor this parameter.:
/sys/bus/pci/devices/<dev>/ccissX/cXdY/lunid
Displays the 8-byte LUN ID used to address logical drive Y of controller X.:
/sys/bus/pci/devices/<dev>/ccissX/cXdY/raid_level
Displays the RAID level of logical drive Y of controller X.:
/sys/bus/pci/devices/<dev>/ccissX/cXdY/usage_count
Displays the usage count (number of opens) of logical drive Y of controller X.:

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 st?(4) 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 run time. 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 distribution). For example:

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:

:

1.
query the adapter about changes to the physical SCSI buses and/or fibre channel arbitrated loop, and:
2.
make note of any new or removed sequential access devices or medium changers.:

The driver will output messages indicating which devices have been added or removed and the controller, bus, target, and lun used to address each device. The driver then notifies the SCSI midlayer 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 midlayer by the cciss driver. Specifically, physical SCSI disk drives are not presented to the SCSI midlayer. The only disk devices that are presented to the kernel are logical drives that the array controller constructs from regions on the physical drives. The logical drives are presented to the block layer (not to the SCSI midlayer). It is important for the driver to prevent the kernel from accessing the physical drives directly, since these drives are used by the array controller to construct the logical drives.

SCSI error handling for tape drives and medium changers

The Linux SCSI midlayer provides an error-handling protocol that is initiated 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.:

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 midlayer. Furthermore, unlike more straightforward SCSI drivers, disk I/O continues through the block side during the SCSI error-recovery process. Therefore, the cciss driver implements only the first two of these actions, aborting the command, and resetting the device. Note also that 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. If the command cannot be aborted and the device cannot be reset, the device will be set offline.

In the event that 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 that 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 that was reset.

SEE ALSO

cciss_vol_status?(8), hpsa?(4), hpacucli?(8), hpacuxe?(8),

and Documentation/blockdev/cciss.txt and Documentation/ABI/testing/sysfs-bus-pci-devices-cciss in the Linux kernel source tree

COLOPHON

This page is part of release 3.74 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man-pages/.


Index

NAME

SYNOPSIS

DESCRIPTION

Options

Supported hardware

Configuration details

FILES

Device nodes

Files in /proc

Files in /sys

SCSI tape drive and medium changer support

Hot plug support for SCSI tape drives

SCSI error handling for tape drives and medium changers

SEE ALSO

COLOPHON