P
ULSAR
.2 SAS P
RODUCT
M
ANUAL
, R
EV
. C
8
3.6
P
ROGRAMMABLE DRIVE CAPACITY
Using the MODE SELECT command, the drive can change its capacity to something less than maximum. See the MODE SELECT (6)
parameter list table in the
SAS Interface Manual
, part number 100293071. A value of zero in the Number of Blocks field indicates that the
drive will not change the capacity it is currently formatted to have. A number other than zero and less than the maximum number of LBAs
in the Number of Blocks field changes the total drive capacity to the value in the Number of Blocks field. A value greater than the maximum
number of LBAs is rounded down to the maximum capacity.
3.7
F
ACTORY
-
INSTALLED OPTIONS
OEMs may order the following items which are incorporated at the manufacturing facility during production or packaged before shipping.
Some of the options available are (not an exhaustive list of possible options):
• Other capacities can be ordered depending on sparing scheme and LBA size requested.
• Single-unit shipping pack. The drive is normally shipped in bulk packaging to provide maximum protection against transit damage. Units
shipped individually require additional protection as provided by the single unit shipping pack. Users planning single unit distribution
should specify this option.
• The
Safety and Regulatory Agency Specifications
, part number 75789512, is usually included with each standard OEM drive shipped,
but extra copies may be ordered.
3.8
T
HIN
P
ROVISIONING
3.8.1
Logical Block Provisioning
The drive is designed with a feature called Thin Provisioning. Thin Provisioning is a technique which does not require Logical Blocks to be
associated to Physical Blocks on the storage medium until such a time as needed. The use of Thin Provisioning is a major factor in SSD
products because it reduces the amount of wear leveling and garbage collection that must be performed. The result is an increase in the
products endurance. For more details on Logical Block Provisioning and Thin Provisioning, Reference the SBC-3 document provided by
the T-10 committee.
3.8.2
Thin Provisioning capabilities
The level of Thin Provisioning support may vary by product model. Devices that support Thin Provisioning are allowed to return a default
data pattern for read requests made to Logical Blocks that have not been mapped to Physical Blocks by a previous WRITE command.
In order to determine if Thin Provisioning is supported and what features of it are implemented requires the system to send a READ
CAPACITY 16 (9Eh) command to the drive. Thin Provisioning and the READ CAPACITY 16 (9Eh) command is defined in the Seagate
SCSI Command Reference 100293068..
A logical block provisioning management enabled (LBPME) bit set to one indicates that the logical unit implements logical block
provisioning management. An LBPME bit set to zero indicates that the logical unit is fully provisioned and does not implement logical block
provisioning management.
A logical block provisioning read zeros (LBPRZ) bit set to one indicates that, for an unmapped LBA specified by a read operation, the
device server sends user data with all bits set to zero to the data-in buffer. An LBPRZ bit set to zero indicates that, for an unmapped LBA
specified by a read operation, the device server may send user data with all bits set to any value to the data-in buffer.
Table 2 Thin Provisioning Product Configuration
Product Configuration
LBPME
LBPRZ
Non-SED
Supported
Supported
SED
Supported
Not Supported
