Bad sectors on a degraded array

Bad sectors on a degraded array

[FLD]

While waiting for my RMA'd disk to return I noticed that one device in
my degraded (4 out of 5) raid5 has developed some bad sectors:
1   Raw_Read_Error_Rate     0x002f   200   200   051    -    0
196 Reallocated_Event_Count 0x0032   200   200   000    -    0
197 Current_Pending_Sector  0x0032   200   200   000    -    3
198 Offline_Uncorrectable   0x0030   200   200   000    -    3

I did some Self-test'ing and got some errors:
# 1  Extended offline    Completed: read failure       50%      6640
1158803416
# 2  Short offline       Completed without error       00%      6637
# 3  Extended offline    Completed: read failure       50%      6634
1158820656

At this point those bad secotrs haven't caused any harm or errors in 
dmesg while the array is mounted r/w and being used. What I'm wondering 
is what kind of steps should I take once the RMA replacement arrives?
I know md doesn't like read errors very much and I'm thinking with smart
output like that it's very likely theres gonna be some read errors during
rebuild?

According to smartmontool documentation this is a pretty common situation 
for a hard disk. There's a nice tutorial how to fix errors like this at:
http://smartmontools.sourceforge.net/badblockhowto.html , so I wonder if 
I should --stop the array and try to manually fix the bad sectors before 
I try rebuilding?

Re: Bad sectors on a degraded array

[Alexander]

See if these are "real" read errors, errors that the OS will see (dd  
if=/dev/sdX of=/dev/null bs=1M).
If yes, get another disk and duplicate the problematic disk using  
dd_rescue and use the new one instead of the old one.
Once the array is up again make sure to do a raid check in regular intervals.
Kind regards,
Alex.

----- Message from fld@r00t3d.com ---------
     Date: Sat, 8 Jan 2011 14:49:53 +0200
     From: FLD <fld@r00t3d.com>
  Subject: Bad sectors on a degraded array
       To: linux-raid@vger.kernel.org


> While waiting for my RMA'd disk to return I noticed that one device in
> my degraded (4 out of 5) raid5 has developed some bad sectors:
> 1   Raw_Read_Error_Rate     0x002f   200   200   051    -    0
> 196 Reallocated_Event_Count 0x0032   200   200   000    -    0
> 197 Current_Pending_Sector  0x0032   200   200   000    -    3
> 198 Offline_Uncorrectable   0x0030   200   200   000    -    3
>
> I did some Self-test'ing and got some errors:
> # 1  Extended offline    Completed: read failure       50%      6640
> 1158803416
> # 2  Short offline       Completed without error       00%      6637
> # 3  Extended offline    Completed: read failure       50%      6634
> 1158820656
>
> At this point those bad secotrs haven't caused any harm or errors in
> dmesg while the array is mounted r/w and being used. What I'm wondering
> is what kind of steps should I take once the RMA replacement arrives?
> I know md doesn't like read errors very much and I'm thinking with smart
> output like that it's very likely theres gonna be some read errors during
> rebuild?
>
> According to smartmontool documentation this is a pretty common situation
> for a hard disk. There's a nice tutorial how to fix errors like this at:
> http://smartmontools.sourceforge.net/badblockhowto.html , so I wonder if
> I should --stop the array and try to manually fix the bad sectors before
> I try rebuilding?
> --
> To unsubscribe from this list: send the line "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>


----- End message from fld@r00t3d.com -----



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