So I'm running DDrescue on a 1.5tb drive. I left 'r' at 2, to attempt to cut down on time needed to complete the task. At 2 1/2 days, it's still going, and now it's making the first pass on retrying bad sectors. Is the sequence of operations for DDRescue, 1 pass untried blocks->retry bad sectors->repeat process according to 'r'?
Note that GNU
ddrescue is a pretty advanced tool. While it offers a lot of flexibility, this warning from their manual should be heeded. If you are merely in the unfortunate situation of trying to get as much of your data back as possible, you may be better off with the dd_rhelp script included with dd_rescue
Here is the desciption of "retries" from the GNU
Exit after given number of retry passes. Defaults to 0. -1 means infinity. Every bad sector is tried only once in each pass. To retry bad sectors detected on a previous run, you must specify a non-zero number of retry passes.
To answer your question directly: after the initial read (pass 1) it will retry two more times on just the sectors that it was unable to read the first time. This means effectively three passes total.
When it gets done with the initial read it will display on stdout
Retrying bad sectors... Retry 1 and then
Retrying bad sectors... Retry 2 before finally