[SATLUG] RAID5 Recovery - ddrescue: 2nd round

Samuel Leon satlug at net153.net
Sun Aug 23 23:10:09 CDT 2009

David Labens wrote:
> I HAD thought that the server was stuck in one place, but upon further review, and comparing screen captures along the way, I see that it is actually making process...
> Notice that each of the 3 readings shows that the ipos & opos (matching) are actually changing and moving higher.  This is good as it shows me that the process is progressing.  However (& I'm not too concerned about this), the speed is showing an "average rate" of 53 B/s - 53 BYTES per Second (a hair over 400 kilobits per second) - about half the speed it was running when it was "splitting error areas" now that it's "copying bad blocks" - & it's just on "retry 1"
> SO, I'm going to pretty much call it a night and let this thing "do that voo doo that it do so well" (to borrow and butcher a line), and I'll post whatever the screen says in the morning!  No use in trying to get it to go any faster when I'm certain it's already pedaling as fast as it can!
> Here's the printout from progress on the current process:

It does appear to be working.  Wish I could understand the process 
better.  info ddrescue has this page in it:

"   The algorithm of ddrescue is as follows:

    1) Optionally read a logfile describing the status of a multi-part or
previously interrupted rescue.

    2) Read the non-damaged parts of the input file, skipping the damaged
areas, until the requested size is reached, or until interrupted by the

    3) Try to read the damaged areas, splitting them into smaller pieces
and reading the non-damaged pieces, until the hardware block size is
reached, or until interrupted by the user.

    4) Try to read the damaged hardware blocks until the specified number
of retries is reached, or until interrupted by the user.

    5) Optionally write a logfile for later use."

So hopefully it does recover everything and/or the damaged area is not 
big enough to matter.


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