Re: [gentoo-user] USB crucial file recovery

[Mick]

On Sunday 28 Aug 2016 11:49:44 Grant wrote:
> I have a USB stick with a crucial file on it (and only an old backup
> elsewhere).  It's formatted NTFS because I wanted to be able to open
> the file on various Gentoo systems and my research indicated that NTFS
> was the best solution.
>
> I decided to copy a 10GB file from a USB hard disk directly to the USB
> stick this morning and I ran into errors so I canceled the operation
> and now the file manager (thunar) has been stuck for well over an hour
> and I'm getting errors like these over and over:
>
> [ 2794.535814] Buffer I/O error on dev sdc1, logical block 2134893,
> lost async page write
> [ 2794.535819] Buffer I/O error on dev sdc1, logical block 2134894,
> lost async page write
> [ 2794.535822] Buffer I/O error on dev sdc1, logical block 2134895,
> lost async page write
> [ 2794.535824] Buffer I/O error on dev sdc1, logical block 2134896,
> lost async page write
> [ 2794.535826] Buffer I/O error on dev sdc1, logical block 2134897,
> lost async page write
> [ 2794.535828] Buffer I/O error on dev sdc1, logical block 2134898,
> lost async page write
> [ 2794.535830] Buffer I/O error on dev sdc1, logical block 2134899,
> lost async page write
> [ 2794.535832] Buffer I/O error on dev sdc1, logical block 2134900,
> lost async page write
> [ 2794.535835] Buffer I/O error on dev sdc1, logical block 2134901,
> lost async page write
> [ 2794.535837] Buffer I/O error on dev sdc1, logical block 2134902,
> lost async page write
> [ 2842.568843] sd 9:0:0:0: [sdc] tag#0 FAILED Result:
> hostbyte=DID_ERROR driverbyte=DRIVER_SENSE
> [ 2842.568849] sd 9:0:0:0: [sdc] tag#0 Sense Key : Hardware Error [current]
> [ 2842.568852] sd 9:0:0:0: [sdc] tag#0 Add. Sense: No additional sense
> information
> [ 2842.568857] sd 9:0:0:0: [sdc] tag#0 CDB: Write(10) 2a 00 01 04 a4
> 58 00 00 f0 00
> [ 2842.568859] blk_update_request: I/O error, dev sdc, sector 17081432
> [ 2842.568862] buffer_io_error: 20 callbacks suppressed
>
> nmon says sdc is 100% busy but doesn't show any reading or writing.  I
> once pulled the USB stick in a situation like this and I ended up
> having to reformat it which I need to avoid this time since the file
> is crucial.  What should I do?
>
> - Grant

Whatever you do, do NOT try to unplug the USB you were writing to unless you 
first manage to successfully unmount it.  If you do pull the USB stick 
regardless of its current I/O state you will likely corrupt whatever file you 
were writing onto, or potentially more.

You could well have a hardware failure here, which manifested itself during 
your copying operation.  Things you could try:

Run lsof to find out which process is trying to access the USB fs and kill it.  
Then see if you can remount it read-only.

Run dd, dcfldd, ddrescue to make an image of the complete USB stick on your 
hard drive and then try to recover any lost files with testdisk.

Use any low level recovery tools the manufacturer may offer - they will likely 
require MSWindows.

Shut down your OS and disconnect the USB stick, then reboot and try again to 
access it, although I would first create an image of the device using any of 
the above tools.

Good luck.
-- 
Regards,
Mick