I have cleared two of my new Seagate 2 TB. Attached here results are for both drives. Total time it took was around 36 hours for 3 Cycles on both of them while running in parellel.
== invoked as: ./preclear_disk.sh -c 3 /dev/sdd
== ST2000DM001-1ER164 Z4Z0L4B9
== Disk /dev/sdd has been successfully precleared
== with a starting sector of 64
== Ran 3 cycles
==
== Using :Read block size = 1000448 Bytes
== Last Cycle's Pre Read Time : 0:-45:-4 (-739 MB/s)
== Last Cycle's Zeroing time : 3:35:24 (154 MB/s)
== Last Cycle's Post Read Time : 6:37:10 (83 MB/s)
== Last Cycle's Total Time : 10:13:33
==
== Total Elapsed Time 29:52:06
==
== Disk Start Temperature: 26C
==
== Current Disk Temperature: 29C,
==
============================================================================
** Changed attributes in files: /tmp/smart_start_sdd /tmp/smart_finish_sdd
ATTRIBUTE NEW_VAL OLD_VAL FAILURE_THRESHOLD STATUS RAW_VALUE
Raw_Read_Error_Rate = 114 100 6 ok 72878800
Spin_Retry_Count = 100 100 97 near_thresh 0
End-to-End_Error = 100 100 99 near_thresh 0
High_Fly_Writes = 89 100 0 ok 11
Airflow_Temperature_Cel = 71 74 45 ok 29
Temperature_Celsius = 29 26 0 ok 29
No SMART attributes are FAILING_NOW
0 sectors were pending re-allocation before the start of the preclear.
0 sectors were pending re-allocation after pre-read in cycle 1 of 3.
0 sectors were pending re-allocation after zero of disk in cycle 1 of 3.
0 sectors were pending re-allocation after post-read in cycle 1 of 3.
0 sectors were pending re-allocation after zero of disk in cycle 2 of 3.
0 sectors were pending re-allocation after post-read in cycle 2 of 3.
0 sectors were pending re-allocation after zero of disk in cycle 3 of 3.
0 sectors are pending re-allocation at the end of the preclear,
the number of sectors pending re-allocation did not change.
0 sectors had been re-allocated before the start of the preclear.
0 sectors are re-allocated at the end of the preclear,
the number of sectors re-allocated did not change.
============================================================================
and below is for second disk.
root@Tower:/tmp# more preclear_report_sde
========================================================================1.15
== invoked as: ./preclear_disk.sh -c 3 /dev/sde
== ST2000DM001-1ER164 Z4Z0KYR8
== Disk /dev/sde has been successfully precleared
== with a starting sector of 64
== Ran 3 cycles
==
== Using :Read block size = 1000448 Bytes
== Last Cycle's Pre Read Time : 0:-58:-44 (-567 MB/s)
== Last Cycle's Zeroing time : 3:18:31 (167 MB/s)
== Last Cycle's Post Read Time : 6:27:15 (86 MB/s)
== Last Cycle's Total Time : 9:46:45
==
== Total Elapsed Time 28:07:08
==
== Disk Start Temperature: 28C
==
== Current Disk Temperature: 30C,
==
============================================================================
** Changed attributes in files: /tmp/smart_start_sde /tmp/smart_finish_sde
ATTRIBUTE NEW_VAL OLD_VAL FAILURE_THRESHOLD STATUS RAW_VALUE
Raw_Read_Error_Rate = 118 100 6 ok 174456264
Spin_Retry_Count = 100 100 97 near_thresh 0
End-to-End_Error = 100 100 99 near_thresh 0
High_Fly_Writes = 99 100 0 ok 1
Airflow_Temperature_Cel = 70 72 45 near_thresh 30
Temperature_Celsius = 30 28 0 ok 30
No SMART attributes are FAILING_NOW
0 sectors were pending re-allocation before the start of the preclear.
0 sectors were pending re-allocation after pre-read in cycle 1 of 3.
0 sectors were pending re-allocation after zero of disk in cycle 1 of 3.
0 sectors were pending re-allocation after post-read in cycle 1 of 3.
0 sectors were pending re-allocation after zero of disk in cycle 2 of 3.
0 sectors were pending re-allocation after post-read in cycle 2 of 3.
0 sectors were pending re-allocation after zero of disk in cycle 3 of 3.
0 sectors are pending re-allocation at the end of the preclear,
the number of sectors pending re-allocation did not change.
0 sectors had been re-allocated before the start of the preclear.
0 sectors are re-allocated at the end of the preclear,
the number of sectors re-allocated did not change.
============================================================================
I think both of them were successfull but just wanted to share results for expert's advice.