Very slow data-rebuild because second drive failing... anything I can do?

[Rhomax]

I've had a 3 (Tb) drive fail which I have replaced and commenced the data-rebuild on. After about 24 hours (at approximately 45% complete) the rate of the rebuild dropped to about 500KB/s (from an initial ~ 10MB/s). I noticed that another drive was now showing around ~2,000 errors.

 

I did a restart and now have the same problem even earlier with only 14% rebuilt after 13 hours and a rate of ~700KB/s. It seems likely to me that the problem is that I have another drive failing (now showing 31 errors) and it's consequently slowing down everything because it's read speed is limited. 

At this rate it seems to me that it's unlikely to ever complete the rebuild as the estimated finish varies between 30 and 60 days.

 

I only have the one parity drive (as most of this data is not that crucial) and I'm ok to lose some data but would like to 'limit the damage' and know which files were affected. 

 

Does anyone have any suggestions as to what I do here?  

- Should I copy off as much data from the currently emulated drive to another location and then start with that drive from scratch?

- Should I copy off as much data as possible from the currently failing disk and then replace that one?

- Any other ideas?

[ChatNoir]

Your diagnostics would provide more information.