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I have a SAMSUNG HM160HI in my laptop at work. This hard disk produced some read errors lately. I reinstalled all Ubuntu packages and my private files don't seem to be affected. Knowing that hard disks replace defect sectors that previously caused read errors with spare ones, I was hoping that the read errors would go away - which they did! I can read the whole hard disk sector by sector without a single error.
Now what doesn't make sense are the S.M.A.R.T. attributes of this disk:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000f 100 100 051 Pre-fail Always - 0
3 Spin_Up_Time 0x0007 252 252 025 Pre-fail Always - 2062
4 Start_Stop_Count 0x0032 002 002 000 Old_age Always - 998454
5 Reallocated_Sector_Ct 0x0033 096 096 010 Pre-fail Always - 41
9 Power_On_Hours 0x0032 085 085 000 Old_age Always - 8160
12 Power_Cycle_Count 0x0032 095 095 000 Old_age Always - 5458
191 G-Sense_Error_Rate 0x0032 065 065 000 Old_age Always - 359719
192 Power-Off_Retract_Count 0x0032 100 100 000 Old_age Always - 66
194 Temperature_Celsius 0x0022 115 070 000 Old_age Always - 41 (Min/Max 11/56)
196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 36224 (0 6)
197 Current_Pending_Sector 0x0012 100 100 000 Old_age Always - 4332
198 Offline_Uncorrectable 0x0030 100 100 000 Old_age Offline - 13478
199 UDMA_CRC_Error_Count 0x0036 252 252 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x000a 252 252 000 Old_age Always - 0
The Offline_Uncorrectable RAW value doesn't go down, it goes up! It used to be 12.9k, now it's at 13.2k. Yet, I don't experience any read errors. The Current_Pending_Sector value also goes up. And the Reallocated_Sector_Ct does't move one bit, even though the hard disk had plenty of opportunities to reallocate the sectors as I was reading out the whole hard disk. I was even copying the hard disk onto itself just in case sectors are only reallocated during write operations.
So what's going on? The hard disk is not reallocating broken sectors in spite of the fact that the firmware is reporting 4k sectors that are pending to be reallocated. Why do I not experience any read errors even if I read the whole disc, sector by sector? Why does Offline_Uncorrectable not go down, since there are no read errors anymore?
Has anybody experienced anything similar?
The hard-disk will be replaced soon. Yet, I have to live with it for a few more days and the erratic behavior puzzles me.