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Just as an example, this is one typical output line.

...........................[12767109](+112394240){X [12792709] X}[12818309](+209715200)

I have gone through the DESCRIPTION OF OUTPUT in safecopy's manpage but I still am not quite sure what exactly it means.

For example, if (+112394240) is "the number of blocks (or bytes) [which is it?] continuously read successfully up to this point." and if (+209715200) is the "number of blocks (or bytes) of recent continuous unreadable data.", then how can the latter be larger than the former?

Additionally, what is the meaning of {X [12792709] X}, does it mean that only one block (block 12792709) was unreadable?

Any clarification would be greatly appreciated.

slm
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Isopycnal Oscillation
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1 Answers1

2

Q#1: Interpreting output

The output seems fairly straightforward. It isn't blocks (or bytes) but rather current block and bytes.

   .      Between 1 and 1024 blocks successfully read.

[xx](+yy){
          Current block and number of bytes continuously read successfully 
          up to this point.

   X      Read  failed  on a block with minimum blocksize and is skipped.  
          Unrecoverable error, destination file is padded with zeros.  Data 
          is now skipped until end of the unreadable area is reached.

   <      Successful read after the end of a bad area causes backtracking 
          with smaller blocksizes to search for the first readable data.

   }[xx](+yy)
          current block and number of bytes of recent continuous unreadable 
          data.

So to breakdown your sample output:

  1. .... - these mean that between 1 and 1024 blocks were successfully read.
  2. [12767109](+112394240) - this is the number of blocks and bytes that were continuously read up to this point. The blocks are in the square brackets [12767109] the total bytes is in the parens, (+112394240).
  3. {X [12792709] X} - reading failed on a block, 12792709, so the data that was unreadable is padded in the destination with zeros.
  4. 12818309](+209715200) - block and continuous number of bytes that were unreadable up to this point.

Q#2: what is the meaning of {X [12792709] X}, does it mean that only one block (block 12792709) was unreadable?

That would be my interpretation of the output and the man page.

References

slm
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  • So, does the byte size (+112394240) include the blocks that were skipped ahead in case they were unsuccessfully read, or does it only include successfully read ones? – Isopycnal Oscillation Sep 12 '14 at 06:42
  • @IsopycnalOscillation - I believe so. It's the number of bytes successfully read up until bytes in block 12792709 failed. From that point, until block `[12818309]` were unreadable. The number of bytes that were unreadable were `(+209715200)`, within that same span. – slm Sep 12 '14 at 06:44