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+
+HPSA - Hewlett Packard Smart Array driver
+-----------------------------------------
+
+This file describes the hpsa SCSI driver for HP Smart Array controllers.
+The hpsa driver is intended to supplant the cciss driver for newer
+Smart Array controllers. The hpsa driver is a SCSI driver, while the
+cciss driver is a "block" driver. Actually cciss is both a block
+driver (for logical drives) AND a SCSI driver (for tape drives). This
+"split-brained" design of the cciss driver is a source of excess
+complexity and eliminating that complexity is one of the reasons
+for hpsa to exist.
+
+Supported devices:
+------------------
+
+Smart Array P212
+Smart Array P410
+Smart Array P410i
+Smart Array P411
+Smart Array P812
+Smart Array P712m
+Smart Array P711m
+StorageWorks P1210m
+
+Additionally, older Smart Arrays may work with the hpsa driver if the kernel
+boot parameter "hpsa_allow_any=1" is specified, however these are not tested
+nor supported by HP with this driver. For older Smart Arrays, the cciss
+driver should still be used.
+
+The "hpsa_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.
+
+HPSA specific entries in /sys
+-----------------------------
+
+ In addition to the generic SCSI attributes available in /sys, hpsa supports
+ the following attributes:
+
+ HPSA specific host attributes:
+ ------------------------------
+
+ /sys/class/scsi_host/host*/rescan
+ /sys/class/scsi_host/host*/firmware_revision
+ /sys/class/scsi_host/host*/resettable
+ /sys/class/scsi_host/host*/transport_mode
+
+ the host "rescan" attribute is a write only attribute. Writing to this
+ attribute will cause the driver to scan for new, changed, or removed devices
+ (e.g. hot-plugged tape drives, or newly configured or deleted logical drives,
+ etc.) and notify the SCSI midlayer of any changes detected. Normally this is
+ triggered automatically by HP's Array Configuration Utility (either the GUI or
+ command line variety) so for logical drive changes, the user should not
+ normally have to use this. It may be useful when hot plugging devices like
+ tape drives, or entire storage boxes containing pre-configured logical drives.
+
+ The "firmware_revision" attribute contains the firmware version of the Smart Array.
+ For example:
+
+ root@host:/sys/class/scsi_host/host4# cat firmware_revision
+ 7.14
+
+ The transport_mode indicates whether the controller is in "performant"
+ or "simple" mode. This is controlled by the "hpsa_simple_mode" module
+ parameter.
+
+ The "resettable" read-only attribute indicates whether a particular
+ controller is able to honor the "reset_devices" kernel parameter. If the
+ device is resettable, this file will contain a "1", otherwise, a "0". This
+ parameter is used by kdump, for example, to reset the controller at driver
+ load time to eliminate any outstanding commands on the controller and get the
+ controller into a known state so that the kdump initiated i/o will work right
+ and not be disrupted in any way by stale commands or other stale state
+ remaining on the controller from the previous kernel. This attribute enables
+ kexec tools to warn the user if they attempt to designate a device which is
+ unable to honor the reset_devices kernel parameter as a dump device.
+
+ HPSA specific disk attributes:
+ ------------------------------
+
+ /sys/class/scsi_disk/c:b:t:l/device/unique_id
+ /sys/class/scsi_disk/c:b:t:l/device/raid_level
+ /sys/class/scsi_disk/c:b:t:l/device/lunid
+
+ (where c:b:t:l are the controller, bus, target and lun of the device)
+
+ For example:
+
+ root@host:/sys/class/scsi_disk/4:0:0:0/device# cat unique_id
+ 600508B1001044395355323037570F77
+ root@host:/sys/class/scsi_disk/4:0:0:0/device# cat lunid
+ 0x0000004000000000
+ root@host:/sys/class/scsi_disk/4:0:0:0/device# cat raid_level
+ RAID 0
+
+HPSA specific ioctls:
+---------------------
+
+ For compatibility with applications written for the cciss driver, many, but
+ not all of the ioctls supported by the cciss driver are also supported by the
+ hpsa driver. The data structures used by these are described in
+ include/linux/cciss_ioctl.h
+
+ CCISS_DEREGDISK
+ CCISS_REGNEWDISK
+ CCISS_REGNEWD
+
+ The above three ioctls all do exactly the same thing, which is to cause the driver
+ to rescan for new devices. This does exactly the same thing as writing to the
+ hpsa specific host "rescan" attribute.
+
+ CCISS_GETPCIINFO
+
+ Returns PCI domain, bus, device and function and "board ID" (PCI subsystem ID).
+
+ CCISS_GETDRIVVER
+
+ Returns driver version in three bytes encoded as:
+ (major_version << 16) | (minor_version << 8) | (subminor_version)
+
+ CCISS_PASSTHRU
+ CCISS_BIG_PASSTHRU
+
+ Allows "BMIC" and "CISS" commands to be passed through to the Smart Array.
+ These are used extensively by the HP Array Configuration Utility, SNMP storage
+ agents, etc. See cciss_vol_status at http://cciss.sf.net for some examples.
+