[prev in list] [next in list] [prev in thread] [next in thread] 

List:       smartmontools-support
Subject:    Re: [smartmontools-support] pending blocks not reliably found in -t long
From:       Christian Franke <Christian.Franke () t-online ! de>
Date:       2012-06-18 17:17:03
Message-ID: 4FDF628F.4090000 () t-online ! de
[Download RAW message or body]

mathog wrote:
> On 17-Jun-2012 22:38, Christian Franke wrote:
>> mathog wrote:
>
>>> picked up some pending sectors.  Strangely these are not always found
>>> with a
>>> smartctl -t long /dev/sda
>>
>> Recently I had a similar issue with a SAMSUNG HE103UJ: 40 pending
>> sectors were reported but both SMART long test and a read scan with
>> ddrescue didn't report any bad sectors. The pending sector count was
>> reset after zeroing each disk block with ddrescue.
>>
>> Apparently this firmware resets the pending status only on write even
>> if the read error was transient. This is vendor specific and typically
>> never documented.
>
> How did you find the bad blocks if subsequent reads completed?

Never :-)


>
> Also bizarre on the WD10EARS drive was what happened when the bad 
> blocks were overwritten, this is the final state:
>
>   5 Reallocated_Sector_Ct   0x0033   200   200   140    Pre-fail  
> Always       -       0
>   7 Seek_Error_Rate         0x002e   200   200   000    Old_age   
> Always       -       0
> 196 Reallocated_Event_Count 0x0032   200   200   000    Old_age   
> Always       -       0
> 197 Current_Pending_Sector  0x0032   200   200   000    Old_age   
> Always       -       0
> 198 Offline_Uncorrectable   0x0030   200   200   000    Old_age   
> Offline      -       0
>
> Note 0 in the reallocated rows, even though we assume they were 
> reallocated when the bad blocks were written.  (Since
> at that point they became readable again.)

Some possible reasons:
- Old sectors now work again, firmware decided to skip reallocation
- Sectors were reallocated but the firmware didn't update 
Reallocated_Sector_Ct raw value
- Attribute 5 means something different
(Attributes are not part of the ATA standard, see FAQ).

Thanks,
Christian


------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/
_______________________________________________
Smartmontools-support mailing list
Smartmontools-support@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/smartmontools-support
[prev in list] [next in list] [prev in thread] [next in thread]