5PB Written, 2476 Sectors Reallocated

So - 5PB written, no unrecoverable errors, and some interesting observations from the stats below. The rate of sector failures has fallen dramatically over the last PB written. It is difficult to be certain of the cause - it may simply be that the weaker flash cells have been largely eliminated now, and those remaining have plenty more life. It may also be related to the fact that, after the last pause at 4PBW, the disk was secure-erased and then Samsung Magician was used to over-provision it by 10% - though it's not clear why that should impact the SMART stats.  Whatever the cause, the SSD is holding up better than predicted:

ID# ATTRIBUTE_NAME          VALUE WORST THRESH TYPE      RAW_VALUE
  5 Reallocated_Sector_Ct   058   058   010    Pre-fail  2476
  9 Power_On_Hours          099   099   000    Old_age   4085
 12 Power_Cycle_Count       099   099   000    Old_age   177
177 Wear_Leveling_Count     023   023   000    Pre-fail  4646
179 Used_Rsvd_Blk_Cnt_Tot   058   058   010    Pre-fail  2476
181 Program_Fail_Cnt_Total  100   100   010    Old_age   0
182 Erase_Fail_Count_Total  058   058   010    Old_age   2476
183 Runtime_Bad_Block       058   058   010    Pre-fail  2476
187 Reported_Uncorrect      100   100   000    Old_age   0
190 Airflow_Temperature_Cel 057   052   000    Old_age   43
195 Hardware_ECC_Recovered  200   200   000    Old_age   0
199 UDMA_CRC_Error_Count    100   100   000    Old_age   0
235 Unknown_Attribute       099   099   000    Old_age   31
241 Total_LBAs_Written      096   096   000    Old_age   9766178591977

The disk will now be rested for a week, and then checked to ensure that the data it was holding can all be read back without error - a short retention test.  Then back to trying to wear it out!