Dell Emulex Family of Adapters - Manual (Page 982)

Emulex Drivers Version 10.2 for Linux User Manual P010081-01A Rev. A
Appendix F. lpfc Driver BlockGuard Functionality
lpfc Driver Module Parameters
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lpfc_prot_guard
This parameter correlates to the SCSI_host_guard_type of the Linux kernel. This
specifies the type of CRC the Linux operating system will pass to the lpfc driver. There
are two guard types: CRC, and IP-CSUM, with values of 0x1 and 0x2, respectively (see
Table F-4).
The default value for lpfc_prot_guard is SHOST_DIX_GUARD_IP. This defines the
format for the guard tag when the data is transferred between the Host and the HBA.
When data is transferred on the wire, the protection data guard tag is always translated
into a T10 DIF CRC. To override the default, a user can pass a module parameter value
with either insmod or modprobe.
The SCSI layer will typically use an IP-CSUM as the method for computing the
protection data guard tag because it uses less CPU overhead.
Table F-3 Protection Data Placement for Supported Profiles
Flag Value BlockGuard Profile Operation
SHOST_DIF_TYPE1_PROTECTION 1 A1 READ_STRIP / WRITE_INSERT
SHOST_DIX_TYPE0_PROTECTION 8 AST2 READ_INSERT / WRITE_STRIP
SHOST_DIX_TYPE1_PROTECTION
SHOST_DIF_TYPE1_PROTECTION 17 AST1 / C1 READ_PASS / WRITE_PASS
Table F-4 lpfc_prot_guard Guard Types
Flag Value Indicates
SHOST_DIX_GUARD_CRC 1 HBA supports T10 DIF CRC
SHOST_DIX_GUARD_IP 2 HBA supports both T10 DIF CRC and IP-CSUM