OSX: dd quits after a few minutes

osx

I'm trying to diagnose a possible disk problem on my OSX machine: I heard some funny noises, so I decided to do a read test of the entire disk using dd.

A few months ago this worked: dd would run for a couple of hours to read 750 GB, and then quit with a message saying 'N bytes transferred in M seconds'

Today, dd runs for a couple of minutes, then terminates with the message 'Killed'. I can't find what causes this.

I'm using this command:
dd if=/dev/disk1s2 of=/dev/null bs=1024k
which should keep going until it runs out of blocks to read.

The system logs don't contain any information on this (no events recorded around the time that dd is killed).

What can I do to solve this?

Best Answer

Use ddrescue (via homebrew or macports) instead of dd which will try and recover from read errors and also log them

ddrescue /dev/disk1s2 hdimage logfile
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