WHAT IS THE PURPOSE OF DD_RHELP ? ---------------------------------
I'll quote a user : "The main purpose of dd_rhelp is to 'save as much
data as fast as possible' and not 'as complete as possible'". But wait : It
seems that completeness of recovered data is your first concerns, isn't it ?
But did you know that could cost lot of time ? When I mean lot, this can be in
some case more than a month, or a year. With these extent, you might have the
concerns of getting 'as much data as fast as possible' and not anymore 'as
complete as possible'.
WHEN CAN I STOP THE RECOVERY ? ------------------------------
> I've been executing the dd_rhelp program for a week now and notice > that my recover file is about 57,5 GB. The broken harddisk was > about 60 GB and has a lot of bad-sectors. > Can I stop the program and edit the recovered file ??
Yep, the remaining disk sectors must be nearly all bad-sectors as
dd_rhelp starts to recover mostly valid sectors. You can stop dd_rhelp (Ctrl-C) whenever you think you've recovered a reasonnable amount of data. When
you have recovered most of the disk, as in your case, you'll end up waiting really long to recover really few data. You'll notice it easily by
looking at dd_rhelp output : jumping to different offset very often and launching dd_rescue on errors each times.
Another trick to decide whether you can definitevely quit the recovery
via dd_rhelp is to look at the small reports of dd_rescue : There's a line containing (in dd_rhelp 0.0.2) :
- Biggest hole size : <X> k - total holes : <Y> k
<X> is the maximum gap size (in one block) of data that has NOT
been checked with dd_rescue. This tells how thin dd_rhelp has seeked the remaining sectors for valid data. <Y> should be the remaining data to be checked with dd_rescue.
At each iteration, the gap size should reduce... But it'll reduce less
and less as you reach the end of the recovery.
As a last advice : In most usual cases, if the recovery takes too long, YOU SHOULD STOP THE RECOVERY BEFORE THE END ! Especially on big hard drives (and 60 Gigs is big) where you expect a lot of bad sectors (a few Megs only is lot). If you launched dd_rhelp to let it runs until the end of the recovery, then you should have used dd_rescue directly, as
dd_rhelp jobs is only to launch dd_rescue on ALL THE DISK by little bits.
And dd_rhelp has been written to choose to start the recovery by the valid data, LETTING YOU THE POSSIBILITY TO STOP THE RECOVERY whenever you think you've waited enough.
IS THE RECOVERY FILE VALID FOR RECOVER OPERATION ? --------------------------------------------------
The recovered data is mapped directly to the recovery file. The gaps that aren't already parsed with dd_rescue are filled with zeroes. The bad sectors data (data that wasn't recoverable) has been written as zeroes too.
Canceling dd_rhelp or dd_rescue with a (Ctrl-C) won't destroy the recovered file or whatever : the file is updated by dd_rescue directly as it recovers data. So you'll find the most accurate copy of your source file/dev in the recover file at anytime.
One last thing : recover operations that you will probably launch on the recovered data might need to work on a file that have the same size than your source file/device.
So you might want to check that your recovered file is the same size than your source file/device.
HOW DO I CHECK THAT THE RECOVERY FILE IS THE SAME SIZE THAN THE
FILE/DEVICE ? -----------------------------------------------------------------------------
The recovery file will have the size to contain the last sectors parsed
via dd_rescue. THIS WON'T BE THE SIZE OF YOUR SOURCE FILE until dd_rhelp launched dd_rescue on the last sectors of your source file/dev. dd_rhelp (as dd_rescue) doesn't know where your source file stops until it tries
to copy beyond the End Of the File (called EOF).
This can be found in the small reports it prints regularly or at the
bottom of the progress bar. (it wasn't quite obvious before version 0.0.3, it is
now specified explicitly in reports.)
dd_rhelp should find quite quickly the EOF, so this shouldn't be a problem most of the time. But, in some rare cases, when the end of the file/device to recover is full of bad sectors, it could take longer to find.
WHAT MUST I DO AFTER USING DD_RHELP TO RECOVER MY DISK INFORMATIONS ? ---------------------------------------------------------------------
This topic is out of this FAQ coverage for now. I may build a complete FAQ on this subject.
Olivier SANTIANO, a french dd_rhelp user shared his experience of
complete process of recovering his hard drive with dd_rhelp and post-dd_rhelp
recovery work : http://f1efq.free.fr/save.htm (in french)
I'VE GOT A QUESTION ABOUT DD_RHELP, WHAT CAN I DO ? --------------------------------------------------
Mail me at vaab@free.fr
I'VE GOT A PROBLEM WITH DD_RHELP, WHAT CAN I DO ? --------------------------------------------------
Mail me at vaab@free.fr
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