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Constellation.2 SAS Product Manual, Rev. H 9
4.3 Performance
• Programmable multi-segmentable cache buffer
• 600 MB/s maximum instantaneous data transfers.
• 7200 RPM spindle. Average latency = 4.16ms
• Background processing of queue
• Supports start and stop commands (spindle stops spinning)
• Adaptive seek velocity; improved seek performance
Note. There is no significant performance difference between Self-Encrypting Drive and standard (non-
Self-Encrypting Drive) models.
4.4 Reliability
• Annualized Failure Rate (AFR) of 0.62%
• Mean time between failures (MTBF) of 1,400,000 hours
• Balanced low mass rotary voice coil actuator
• Incorporates industry-standard Self-Monitoring Analysis and Reporting Technology (S.M.A.R.T.)
• 5-year warranty
4.5 Formatted capacities
Standard OEM models are formatted to 512 bytes per block. The block size is selectable at format time and
must be a multiple of 4 bytes. Users having the necessary equipment may modify the data block size before
issuing a format command and obtain different formatted capacities than those listed.
To provide a stable target capacity environment and at the same time provide users with flexibility if they
choose, Seagate recommends product planning in one of two modes:
1. Seagate designs specify capacity points at certain block sizes that Seagate guarantees current and future
products will meet. We recommend customers use this capacity in their project planning, as it ensures a
stable operating point with backward and forward compatibility from generation to generation. The current
guaranteed operating points for this product are:
Capacity (Blocks)
Sector Size
ST91000640SS, ST91000641SS &
ST91000642SS
ST9500620SS, ST9500621SS &
ST9500622SS
Decimal Hex Decimal Hex
512 1,953,525,168 74706DB0 976,773,168 3A386030
520 1,923,076,936 729FD348 961,538,472 394FE9A8
528 1,876,331,336 6FD68B48 938,165,672 37EB45A8
4.6 Programmable 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.