input/output error on disk(?)

[Tony Nelson]

On 09-10-15 01:29:22, charles zeitler wrote:
> when trying to copy a certain file, i get the message:
> cp: reading 'file' :  Input/output error
> 
> i took the volume it was on offline, & did a forced
> e2fsck.  same thing.
> 
> smartctl -H tells me the drive 'passes' .
> 
> i can change the name with mv, no problem there.
> 
> are there any other (non-destructive) steps i can take?

It is likely that the disk has one or more bad blocks.  Use
`smartctl -a /dev/sdx` to see all the data (or -A to see only the 
attributes) and look at the raw values of Current_Pending_Sector and 
Reallocated_Event_Count.  The first reflects unfixed problems, and the 
second fixed problems.  If both numbers are low, I would just keep 
using the drive, though I would first do a long test with `smartctl -t 
long /dev/sdx` (wait until the indicated time and then do a `smartctl -
a /dev/sdx` to see what happened) and then enabled Automatic Offline 
Testing with `smartctl -o on /dev/sdx` (this will help keep up with 
sectors as they go bad, without unnecessary data loss).

A program such as ddrescue (`yum install ddrescue`, `info ddrescue`) 
may help to salvage the damaged file(s).

-- 
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