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Constellation.2 SAS Product Manual, Rev. K 53
9.8.1 Levels of PI
There are 4 types of Protection Information.
Type 0 - Describes a drive that is not formatted with PI information bytes. This allows for legacy support in non-PI sys-
tems.
Type 1 - Provides support of PI protection using 10 and 16 byte commands. The RDPROTECT and WRTPROTECT bits
allow for checking control through the CDB. Eight bytes of Protection Information are transmitted at LBA boundaries
across the interface if RDPROTECT and WRTPROTECT bits are nonzero values. Type 1 does not allow the use of 32 byte
commands.
Type 2 - Provides checking control and additional expected fields within the 32 byte CDBs. Eight bytes of Protection
Information are transmitted at LBA boundaries across the interface if RDPROTECT and WRTPROTECT bits are nonzero
values. Type 2 does allow the use of 10 and 16 byte commands with zero values in the RDPROTECT and WRTPROTECT
fields. The drive will generate 8 bytes (e.g.0xFFFF) 8 bytes of Protection Information to be stored on the media, but the
8 bytes will not be transferred to the host during a read command.
Type 3 - Seagate products do not support Type 3.
9.8.2 Setting and determining the current Type Level
A drive is initialized to a type of PI by using the format command on a PI capable drive. Once a drive is formatted to a
PI Type, it may be queried by a Read Capacity (16) command to report the PI type which it is currently formatted to. PI
Types cannot coexist on a single drive. A drive can only be formatted to a single PI Type. It can be changed at anytime
to a new Type but requires a low level format which destroys all existing data on the drive. No other vehicle for chang-
ing the PI type is provided by the T10 SBC3 specification.
Type 1 PI format CDB command: 04 90 00 00 00 00, Write Buffer: 00 A0 00 00
Type 2 PI format CDB command: 04 D0 00 00 00 00, Write Buffer: 00 A0 00 00
9.8.3 Identifying a Protection Information drive
The Standard Inquiry provides a bit to indicate if PI is support by the drive. Vital Product Descriptor (VPD) page 0x86
provides bits to indicate the PI Types supported and which PI fields the drive supports checking.
Note. For further details with respect to PI, please refer to SCSI Block Commands - 3 (SBC-3) Draft Standard doc-
umentation.