[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Bug-ddrescue] Input/output error

From: Dave Burton
Subject: Re: [Bug-ddrescue] Input/output error
Date: Tue, 02 Oct 2007 09:47:22 -0400 (EDT)

address@hidden (Antonio Diaz Diaz) wrote
to address@hidden (Chris Date):

> The "Input/output error" message means that ddrescue
> received an error condition from the system when trying
> to write data to the output file.  It seems the drive
> you are writing to is also having problems.

Hi Chris,

This happened to me back in October 2005.

While using ddrescue to recover data from drive
#1 onto drive #2, drive #2 failed.  So then I
was in the situation of having to do data
recovery from drive #2 onto ANOTHER new drive.

I did that (using ddrescue, of course), but the
data thus re-rescued was incomplete.  Only those
sectors which had been rescued from drive #1
onto drive #2, AND from drive #2 onto drive #3,
were correct on drive #3.

(Note: in this scenario I was glad that drive #2
was a whole drive, rather than an image file.
That avoided worries about failing sectors in
the destination drive's inode and/or indirect
blocks for the image file.)

Before I could resume the original data recovery
process (this time from drive #1 onto drive #3)
I had to merge the two ddrescue log files into
a single log file that showed which sectors
had successfully made it both from drive #1 onto
drive #2, and from drive #2 onto drive #3.

So I wrote a Perl program, ddrlogand.pl, to merge
the two log files.  Combining the two log files
is basicly a "logical AND" operation.  It starts
with the original ddrescue log file (drive #1 ->
drive #2), and modifies it by invalidating those
sectors which were successfully rescued the
first time, but could not be successfully copied
from drive #2 to drive #3.

After merging the two log files, you can resume
the original data recovery process from drive #1,
this time with drive #3 as the destination.

Since merging the logfiles makes a "logical AND"
of the two log files, I called the Perl program
to combine two ddrescue log files "ddrlogand.pl"
(ddrescue logfile logical AND).  It is one of
the 16 programs in ddr2sr.zip, which you can
download from my web site:


reply via email to

[Prev in Thread] Current Thread [Next in Thread]