linux/Documentation/ABI/testing/sysfs-class-scsi_host
Scott Teel da0697bd30 [SCSI] hpsa: allow user to disable accelerated i/o path
Allow SSD Smart Path for a controller to be disabled by
the user, regardless of settings in controller firmware
or array configuration.

To disable:     echo 0 > /sys/class/scsi_host/host<id>/acciopath_status
To re-enable:   echo 1 > /sys/class/scsi_host/host<id>/acciopath_status
To check state: cat /sys/class/scsi_host/host<id>/acciopath_status

Signed-off-by: Scott Teel <scott.teel@hp.com>
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2014-03-15 10:19:07 -07:00

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What: /sys/class/scsi_host/hostX/isci_id
Date: June 2011
Contact: Dave Jiang <dave.jiang@intel.com>
Description:
This file contains the enumerated host ID for the Intel
SCU controller. The Intel(R) C600 Series Chipset SATA/SAS
Storage Control Unit embeds up to two 4-port controllers in
a single PCI device. The controllers are enumerated in order
which usually means the lowest number scsi_host corresponds
with the first controller, but this association is not
guaranteed. The 'isci_id' attribute unambiguously identifies
the controller index: '0' for the first controller,
'1' for the second.
What: /sys/class/scsi_host/hostX/acciopath_status
Date: November 2013
Contact: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Description: This file contains the current status of the "SSD Smart Path"
feature of HP Smart Array RAID controllers using the hpsa
driver. SSD Smart Path, when enabled permits the driver to
send i/o requests directly to physical devices that are part
of a logical drive, bypassing the controllers firmware RAID
stack for a performance advantage when possible. A value of
'1' indicates the feature is enabled, and the controller may
use the direct i/o path to physical devices. A value of zero
means the feature is disabled and the controller may not use
the direct i/o path to physical devices. This setting is
controller wide, affecting all configured logical drives on the
controller. This file is readable and writable.