Question re. hard read errors

Raphaël Marmier raphael at
Fri Aug 8 01:31:52 PDT 2003

Try using dd to grab all possible bits of that file:
dd if=/path/tothe/file of=/path/to/newfile conv=sync,noerror >ddlog.txt 

you get the log of all errors and faulty blocks in ddlog.txt

This will make a copy of the file with unreadable blocks converted to 
blank. Then you should fix the compresssed archive with the proper 
utility (although I don't know exactly how), then you should be able to 
untar it. Maybe the information on which files where lost will even be 

If it turns out you didn't loose that much, it will spare you the 
effort to read the disk harder. In case you really lost damn imporant 
stuff, you can send the disk to a data recovery company, but it costs 

Hope this helps


Le Vendredi, 8 aoû 2003, à 01:33 Europe/Zurich, Richard Johnson a écrit 

> I have a 1.5Gb file stored on a FreeBSD 4.8 disk drive and the system 
> is giving me hard read errors when I try reading it.  It appears as 
> though this disk has a few bad blocks. :(   Unfortunately, it's a 
> compressed tar file and I (stupidly!) erased the file from the 
> original computer before untar'ing it here and finding the errors!  
> I'd like to recover as much as possible of this file before writing 
> off the entire thing.
> I looked at /usr/src/sys/dev/ata/ata-disk.c and found the retry count 
> was set to 3.  I changed it to 10.  After the first error (which is, 
> indeed, reported 10 times) the system reports that it's going into PIO 
> mode and I still hear the same amount of hammering on the drive after 
> that and only one error message produced.
> Is there some way I can force the system to retry 10 or more times for 
> each and every block?  Maybe there's some other utility I can use 
> which tries harder to read the blocks?
> ANY pointers to information would be greatly appreciated.
> /raj
> _______________________________________________
> freebsd-questions at mailing list
> To unsubscribe, send any mail to 
> "freebsd-questions-unsubscribe at"

More information about the freebsd-questions mailing list