Disk with past errors has Reallocated_Sector_Ct=0

I have one disk which clearly had at least one bad sector before 
(excerpts from the smart log show this), the errors had been cleared, 
but it still reports Reallocated_Sector_Ct=0
I would expect Reallocated_Sector_Ct to be >0 after any number of bad 
sectors had been cleared.

Is this an incorrect understanding of how reallocation works, or this 
disk just reports the wrong Reallocated_Sector_Ct?

In the past, after this disk failed, I rewrote all of it with zeros to 
clear any bad sectors.

=== last error from SMART log  showing it had errors===
Error 215 occurred at disk power-on lifetime: 6197 hours (258 days + 5 
hours)
   When the command that caused the error occurred, the device was 
active or idle.

   After command completion occurred, registers were:
   ER ST SC SN CL CH DH
   -- -- -- -- -- -- --
   40 51 08 f2 44 ec 4d  Error: UNC 8 sectors at LBA = 0x0dec44f2 = 
233587954

=== test log from the SMART log showing the cleared errors===
SMART Self-test log structure revision number 1
Num  Test_Description    Status                  Remaining 
LifeTime(hours)  LBA_of_first_error
# 1  Extended offline    Completed without error       00% 6250         -
# 2  Extended offline    Completed without error       00% 6212         -
# 3  Extended offline    Completed without error       00% 6205         -
# 4  Extended offline    Completed: read failure       70% 6199         
224815107
# 5  Extended offline    Completed without error       00% 3212         -

Hitachi Travelstar 5K250 HTS542525K9SA00

Yuri

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