Seagate Pulsar XT.2 Manual download pdf (Page 46)

38 Pulsar XT.2 SAS Product Manual, Rev. B

9.0 Defect and error management

Seagate continues to use innovative technologies to manage defects and errors. These technologies are

designed to increase data integrity, perform drive self-maintenance, and validate proper drive operation.

SCSI defect and error management involves drive internal defect/error management and SAS system error

considerations (errors in communications between the initiator and the drive). In addition, Seagate provides

the following technologies used to increase data integrity and drive reliability:

• Background Media Scan (see Section 9.4)

• Auto-Reallocation (see Section 9.5)

The read error rates and specified storage capacities are no

t dependent on host (initiator) defect management

routines.

9.1 Drive internal defects/errors

During the initial drive manufacturing test operation at the factory, media defects are identified, tagged as being

unusable, and their locations recorded on the drive primary defects list (referred to as the “P’ list). At factory

format time, these known defects are also deallocated, that is, marked as retired and the location listed in the

defects reallocation table. The “P” list is not altered after factory formatting. Locations of defects found and

reallocated during error recovery procedures after drive shipment are listed in the “G” list (defects growth list).

The “P” and “G” lists may be referenced by the initiator using the READ DEFECT DATA command.

Details of the SCSI commands supported by the drive are described in the SAS Interface Manual. Also, more

information on the drive Error Recovery philosophy is presented in the SAS Interface Manual.

The drive uses a vendor unique format to report defects via the READ DEFECT DATA command pending T10

standardization of a format for Solid State Devices. This format defect type is defined as 110b in the SCSI

FORMAT UNIT command. The definition of the 110b format is defined in the following table.

Table 11: SSD Physical format address descriptor

Bit

Byte

7 6 5 4 3 2 1 0

0 (MSB) MEDIA ID

1 (LSB)

2 CHANNEL

3 DIE

4 (MSB) BLOCK

5 (LSB)

6 RESERVED

7 VENDOR UNIQUE

The MEDIA ID field contains an identifier f

or the flash controller for devices that utilize more than one flash

controller.

The CHANNEL field contains the channel number

within the corresponding Flash Controller.

1 2 ... 41 42 43 44 45 46 47 48 49 50 51 ... 73 74

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Seagate Pulsar XT.2 Manual Page 46