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PULSAR.2 SAS PRODUCT MANUAL, REV. C 9
3.8.3 UNMAP
The UNMAP command requests that the device server break the association of a specific Logical Block address from a Physical Block,
thereby freeing up the Physical Block from use and no longer requiring it to contain user data. An unmapped block will respond to a READ
command with data that is determined by the setting of the LBPRZ bit in the READ CAPACITY parameter data.
3.8.4 FORMAT UNIT command
A device which supports Thin Provisioning will be capable of performing a SCSI FORMAT UNIT command which allocates Logical Blocks
Addresses that are not linked to Physical Block Locations. A FORMAT command will cause all LBAs to become unmapped.
3.8.5 Protection Information (PI) and Security (SED)
The requirements in this section apply to any device which supports LBA unmapping.
In SCSI devices, umapped LBAs are defined as part of the Thin Provisioning model. Support of the Thin Provisioning model is indicated by
the LBPME bit having a value of '1' in the READ CAPACITY (16) parameter data.
When a region of LBA's are erased via cryptographic erase, as part of the erase, the drive shall unmap those LBAs.
If the host attempts to access an unmapped or trimmed LBA, the drive shall return scrambled data. For a given LBA, the data shall be
identical from access to access, until that LBA is either updated with actual data from the host or that LBA is cryptographically erased. The
drive shall report a value of '0' in the LBPRZ field returned in the READ CAPACITY (16) parameter data.
If the host attempts to access an unmapped LBA on a drive that has been formatted with Protection Information (PI), the drive shall return
scrambled PI data for that LBA. Depending on the value of the RDPROTECT field in the data-access command CDB, this may result in the
drive returning a standard PI error to the host.
If the host reduces the addressable capacity of the drive via a MODE SELECT command, the drive shall unmap or trim any LBA within the
inaccessible region of the device.
Additionally, an UNMAP command is not permitted on a locked band.
Table 3 PI and SED Drive Configuration
DRIVE CONFIGURATION
Standard SED
PI Setting Disabled Enabled Disabled Enabled
PROT_EN bit 010 1
LBPME bit 111 1
LBPRZ bit 110 0
PI Check Requested N/A Yes No N/A Yes No
DATA Returned for
Thin Provisioned LBA
0x00 0x00 0x00 Random None Random
PI Returned for
Thin Provisioned LBA
None 0xFF 0xFF None None
Scrambled
PI data
PI Check Performed N/A No No N/A Yes No
Error reported to Host No No No No Yes No