[Bug-ddrescue] freezes

[ben chang]

Hello,

I don't know whether this is a bug, or just normal behavior for a dying hard
drive.  ddrescue keeps hard-freezing the machine part of the way through the
rescue operation; even alt-sysrq keys won't respond.  How resilient is ddrescue
to read errors?  Are there some which are so bad that it'll make this happen?

The details:

ddrescue version: 1.2
OS: gnu/linux ubuntu 8.04 i386
dying drive: western digital, SATA, 500GB
target drive: seagate barracuda, SATA, 500GB
invocation: ddrescue -v -n /dev/sdb1 /dev/sdc1 ddrescue_log

about 73 GB in it completely freezes.  

the log shows only two entries.  

0              0x10C1A10000 +
0x10C1A1000    0x63AEF70400 ?

repeated passes with ddrescue pick up with around 70GB rescued, and then die
again around 73 GB.

smartctl shows 6 CURRENT_PENDING_SECTOR errors.  This is why I'm trying to
rescue the drive; I have 7 of them, went through a round of zeroing the bad
blocks, got that number down to 0; the drive passed the smartctl tests and
passed fsck (before, fsck was causing system freezes too).  I thought
everything was ok and then the number went right back up to 6 the next day.

Should ddrescue be able to cope with the drive even if it has those errors?

Should I zero and reallocate those blocks again before ddrescue'ing?  Or will
more just keep coming back?

Would it be better to use ddrescue to jump past the problem areas and then work
back towards them?  

thanks,

--Ben