Complex cooked/raw value dependency of attribute 5 on Hitachi Deskstar T7K250

Dan Lukes <[email protected]>
Newsgroups gmane.linux.utilities.smartmontools
Message-ID <[email protected]>
Note this is neither bug report nor question. It's report about 
surprising behavior of Hitachi's SMART.

  ------------

I received disc affected by "unreadable sectors issue" causing the disk 
can't be mounted (broken filesystem, unable to repair because of 
unreadable sectors).

For this kind of issues I compiled my own utility to refresh the 
affected disc. It read all disc sectors and write back all those 
considered unreadable or suspicious (I'm trying to catch recoverable 
read errors as well). Write should trigger internal relocation of broken 
sector causing there will be o unreadable sector at user level visible.

Don't hesitate, I need no help with such task, it works like a charm. 
I'm writing here because I monitored the SMART attributes during the 
refresh process and I got some result I would like to share.

The initial values as well as snaps of selected atributes are on bottom.

It revealed that this disc/firmware doesn't save worst values. Cooked 
value and worst value is same all the times - despite cooked value has 
increased. The exception is the attribute 199, it seems the WORST value 
is constant and unrelated to value at all.

Well, it is noticeable "feature", but what's surprising me more is the 
relationship of RAW and COOKED value of attribute 5.

Despite raw value of attribute 5 has increased monotonically during the 
refresh (expected behavior), the cooked value increased for a while 
before it start to descend (unexpected behavior by me).

Yes, I'm aware that exact meaning of RAW value is vendor specific - and 
even meaning of cooked value is not defined. Despite of it I can be 
surprised by particular behavior, isn't it ?

OK. There's no conclusion from such test. Just recorded values and 
behavior of particular disc. Someone may consider it interesting despite 
the true value of this information is rather questionable ;-)

Regards


Dan


  -------------------------------------------------------------
Model Family:     Hitachi Deskstar T7K250
Device Model:     HDT722525DLA380
Firmware Version: V44OA96A
User Capacity:    250,059,350,016 bytes [250 GB]

SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAGS    VALUE WORST THRESH FAIL RAW_VALUE
   1 Raw_Read_Error_Rate     PO-R--   084   084   016    -    11600063
   2 Throughput_Performance  P-S---   100   100   050    -    0
   3 Spin_Up_Time            POS---   106   106   024    -    325
   4 Start_Stop_Count        -O--C-   100   100   000    -    78
   5 Reallocated_Sector_Ct   PO--CK   005   005   005    NOW  1592
   7 Seek_Error_Rate         PO-R--   100   100   067    -    0
   8 Seek_Time_Performance   P-S---   138   138   020    -    30
   9 Power_On_Hours          -O--C-   090   090   000    -    75364
  10 Spin_Retry_Count        PO--C-   100   100   060    -    0
  12 Power_Cycle_Count       -O--CK   100   100   000    -    78
192 Power-Off_Retract_Count -O--CK   099   099   050    -    1203
193 Load_Cycle_Count        -O--C-   099   099   050    -    1203
194 Temperature_Celsius     -O----   141   141   000    -    39 (Min/Max 
18/64)
196 Reallocated_Event_Count -O--CK   015   015   000    -    1621
197 Current_Pending_Sector  -O---K   098   098   000    -    206
198 Offline_Uncorrectable   ---R--   100   100   000    -    0
199 UDMA_CRC_Error_Count    -O-R--   200   253   000    -    0
  -------------------------------------------------------------

Snapshots of selected attributes during disk refresh process.

  ------------------------------------

   5 Reallocated_Sector_Ct   PO--CK   005   005   005    NOW  1598
196 Reallocated_Event_Count -O--CK   015   015   000    -    1630
197 Current_Pending_Sector  -O---K   098   098   000    -    202

   5 Reallocated_Sector_Ct   PO--CK   005   005   005    NOW  1602
196 Reallocated_Event_Count -O--CK   013   013   000    -    1635
197 Current_Pending_Sector  -O---K   098   098   000    -    197

   5 Reallocated_Sector_Ct   PO--CK   005   005   005    NOW  1614
196 Reallocated_Event_Count -O--CK   013   013   000    -    1648
197 Current_Pending_Sector  -O---K   100   100   000    -    187

   5 Reallocated_Sector_Ct   PO--CK   006   006   005    -    1632
196 Reallocated_Event_Count -O--CK   012   012   000    -    1669
197 Current_Pending_Sector  -O---K   100   100   000    -    143

   5 Reallocated_Sector_Ct   PO--CK   006   006   005    -    1644
196 Reallocated_Event_Count -O--CK   011   011   000    -    1685
197 Current_Pending_Sector  -O---K   100   100   000    -    126

   5 Reallocated_Sector_Ct   PO--CK   007   007   005    -    1647
196 Reallocated_Event_Count -O--CK   011   011   000    -    1690
197 Current_Pending_Sector  -O---K   100   100   000    -    117

   5 Reallocated_Sector_Ct   PO--CK   006   006   005    -    1655
196 Reallocated_Event_Count -O--CK   010   010   000    -    1698
197 Current_Pending_Sector  -O---K   100   100   000    -    112

   5 Reallocated_Sector_Ct   PO--CK   006   006   005    -    1669
196 Reallocated_Event_Count -O--CK   009   009   000    -    1712
197 Current_Pending_Sector  -O---K   100   100   000    -    105

   5 Reallocated_Sector_Ct   PO--CK   006   006   005    -    1671
196 Reallocated_Event_Count -O--CK   009   009   000    -    1714
197 Current_Pending_Sector  -O---K   100   100   000    -    103

   5 Reallocated_Sector_Ct   PO--CK   006   006   005    -    1684
196 Reallocated_Event_Count -O--CK   009   009   000    -    1728
197 Current_Pending_Sector  -O---K   100   100   000    -    94

   5 Reallocated_Sector_Ct   PO--CK   006   006   005    -    1701
196 Reallocated_Event_Count -O--CK   008   008   000    -    1746
197 Current_Pending_Sector  -O---K   100   100   000    -    83

   5 Reallocated_Sector_Ct   PO--CK   005   005   005    NOW  1740
196 Reallocated_Event_Count -O--CK   005   005   000    -    1791
197 Current_Pending_Sector  -O---K   100   100   000    -    50

   5 Reallocated_Sector_Ct   PO--CK   005   005   005    NOW  1780
196 Reallocated_Event_Count -O--CK   003   003   000    -    1840
197 Current_Pending_Sector  -O---K   100   100   000    -    50

   5 Reallocated_Sector_Ct   PO--CK   005   005   005    NOW  1797
196 Reallocated_Event_Count -O--CK   001   001   000    -    1877
197 Current_Pending_Sector  -O---K   100   100   000    -    3

   5 Reallocated_Sector_Ct   PO--CK   004   004   005    NOW  1806
196 Reallocated_Event_Count -O--CK   001   001   000    -    1886
197 Current_Pending_Sector  -O---K   100   100   000    -    1
  ------------------------------------


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