Users Guide

Broadcom DRVLin-UG128-100
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Emulex Drivers for Linux User Guide
A.2 Enabling BlockGuard
BlockGuard is disabled by default. To enable it, the lpfc_enable_bg parameter must be passed to the driver as follows:
insmod lpfc.ko lpfc_enable_bg=1
For a permanent configuration that persists across system reboots, create the /etc/modprobe.d/elx-lpfc.conf file,
and place the following line into it:
options lpfc lpfc_enable_bg=1
Additional module parameters can be added to this line, separated by spaces.
A.3 SCSI Command Support – SCSI Operation Codes
When there are both READ and WRITE requests, the CDB passed to the adapter from the initiator host has a read protect/
write protect (RDPROTECT/WRPROTECT) field that indicates to the target whether to perform data integrity verification. It also
indicates whether to transfer protection data between the initiator and target. The adapter does not know if a target supports
protection information or with which type of protection it is formatted. The initiator host, which has this knowledge, always
prepares a CDB with the appropriate RDPROTECT/WRPROTECT information, depending on target format and capabilities. The
request also includes information about the protection type with which the target has been formatted.
In addition, the initiator host provides the adapter with an operation code that tells the controller how to place the protection
data for the type of I/O to perform. Each I/O is logically a two-step process. The data is transferred between the initiator host
and the adapter (over the PCI bus) and between the adapter and the target (over the SAN) as shown in the following figure.
The type of operation defines whether the data transfer has protection data.
Figure 2: Data Transfer between the Initiator Host and the Adapter