[Bug-ddrescue] RE: Reading logfile of recovery

[ddrescue.admin]

Rdkrsr

Well the logfile format is documented in the ddrescue files...

But effectively you have a big chunk of readable data (0x4352F000 - I can't
remember if it is bytes / blocks etc!) at the beginning of the disk:
0x00000000  0x4352F000  +
Then a block of unreadable data
0x4352F000  0x00000200  -
Then possibly readable data
0x4352F200  0x00011000  *
Then Readable data
0x43540200  0x007A2E00  +


Etc etc 
+ = readable
- = unreadable
* = an area still to be processed (the rest of the initial data block that
was attempted with the failed block, so it needs to be read in smaller
blocks)

If they are video files then you probably have some with 'holes' in from the
failed block - may be possible to recover the rest of the file to a usable
state.  You will need to work out how the size of readable data areas
compares with your expected file sizes to see if it is worth persevering -
DDRescue will get the disk sectors into a file but you will then need
another tool to recover the file system from that raw data.

The 'average rate' will be very low while it is trying to read failed
sectors and then will speed up when it reads good data... I usually get
about 9MB/sec when using DDRescue to duplicate disks....

regards

David Mitchell

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Subject: Bug-ddrescue Digest, Vol 57, Issue 7

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Today's Topics:

   1. Is it possible to gather sth from the logfile of an       ongoing
      rescue (rdkrsr)


----------------------------------------------------------------------

Message: 1
Date: Thu, 28 Oct 2010 16:45:12 +0200
From: rdkrsr <address@hidden>
Subject: [Bug-ddrescue] Is it possible to gather sth from the logfile
        of an   ongoing rescue
To: address@hidden
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset=ISO-8859-1

Hi!

I have a corrupt 2 TB hard disk with mainly video files (NTFS, one
volume, recorded by an DVB-S device). I have not very much hope to
rescue something because at the beginning of the weird behaviour of
the drive I might have worsened the state of it (use of Partition
Magic etc.). There is no recognition of any file system and there are
i/o errors. At the beginning the movies were "pausing" more and more
during playback. Then it took unbearably long to copy something off of
the drive. So I guess the drive is lost.

Question: Yesterday I startet a ddrescue and it shows at the moment an
average rate of 500 kB/s, which would mean more than 30 days for the
process. So I wonder if there is a possibility to say something about
the usefullness of the copied data by looking at the logfile.

The file starts like following and goes on like that (+,-,*,+,-,*, ...)

Cheers,
rdkrsr

# Rescue Logfile. Created by GNU ddrescue version 1.11
# current_pos  current_status
0xBCCAC0200     ?
#      pos        size  status
0x00000000  0x4352F000  +
0x4352F000  0x00000200  -
0x4352F200  0x00011000  *
0x43540200  0x007A2E00  +
0x43CE3000  0x00000200  -
0x43CE3200  0x0001D000  *
0x43D00200  0x0020CE00  +
0x43F0D000  0x00000200  -
0x43F0D200  0x00013000  *
0x43F20200  0x0032DE00  +
0x4424E000  0x00000200  -
0x4424E200  0x00012000  *
0x44260200  0x0034AE00  +
0x445AB000  0x00000200  -
0x445AB200  0x00015000  *
0x445C0200  0x0032AE00  +
0x448EB000  0x00000200  -
0x448EB200  0x00015000  *
0x44900200  0x00215E00  +
0x44B16000  0x00000200  -
0x44B16200  0x0001A000  *
0x44B30200  0x00AD8E00  +
0x45609000  0x00000200  -
0x45609200  0x00017000  *
0x45620200  0x016E4E00  +
0x46D05000  0x00000200  -
0x46D05200  0x0001B000  *
0x46D20200  0x0020FE00  +
0x46F30000  0x00000200  -
0x46F30200  0x00010000  *



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