[Bug-ddrescue] Proposed ddrescue improvement

[Neil Steiner]

Hello ddrescue Team,

First of all, thank you for the wonderful tool that ddrescue is.  I have 
a small suggestion that might benefit other ddrescue users as it would 
have benefited me:  Adding a command line option to enable periodic 
sync() calls, to force the OS to flush its buffers.

My case is as follows:  I have been working on recovering data from a 
friend's dying drive.  After much experimenting with both command line 
arguments and the hardware (cooling/freezing the drive, using an older 
more lenient computer, ...), I had finally managed to recover 259,994 MB 
of the requested 260,000 MB, and I was already planning my fschk on the 
recovered data.  But today I apparently lost power for a brief while, 
and even though I was using -y for synchronous writes on a journaled 
filesystem, the OS had apparently been caching most everything in 
memory.  I'm back down to only 80,000 MB recovered, and hoping that I'll 
be able to regain the additional 80,000 MB that has disappeared.  (Yes, 
it's my own fault for not having a suitable UPS on that machine, and for 
being lulled into complacency by ddrescue's remarkable ability to pick 
up where it left off.)

I think this proposed additional command line switch should be fairly 
simple to implement, and I expect that it would have very little impact 
on the remainder of the tool functionality.  I am happy to discuss this 
in greater detail if that would be helpful.

Regards,

Neil