DDrescue help please

Hello guys!

I'm trying to copy data from a failing 3TB seagate drive (yes one of those defective seagate drives), using the following comand from a rescue disk:

sudo ddrescue -v -r 3 /dev/sda /dev/sdb logfile

1: Where is the logfile being created / stored ? ( i didn't specify a 3rd drive as destination)

2: If I were to stop, how could I resume ? I actually had to add --force to the beginning of the command in order to proceed

3:I see a line where it says that 1834 GB have been rescued
then a 2nd line that says 1958 GB have been rescued (is that the 2nd pass)

4: What happens if I stop this right now? will I have access to what has been rescued ?
Or will I just lose everything



Thanks!

orion23 said:

Hello guys!

I'm trying to copy data from a failing 3TB seagate drive (yes one of those defective seagate drives), using the following comand from a rescue disk:

sudo ddrescue -v -r 3 /dev/sda /dev/sdb logfile

1: Where is the logfile being created / stored ?

2: If I were to stop, how could I resume ? I actually had to add --force to the beginning of the command in order to proceed

3:I see a line where it says that 1834 GB have been rescued
then a 2nd line that says 1958 GB have been rescued

4: What happens if I stop this right now? will I have access to what has been rescued ?



Thanks!

Click to expand...

#1 is likely the directory that you're running the command from. Using a recovery media, this is probably a non-persistant storage space.

#2 I haven't used the application, but from some quick google-fu, it sounds like you'll just re-run the command and it will read the logfile and pick up from there. If it can't find the log file, it will start over from the beginning. The man page indicates you had to add --force because the target was a device and not a file.

#3 with -v verbosity enabled, you're likely getting progress updates, with the most recent line being the current cumulative total.

#4 I wouldn't expect you'd be able to mount the incomplete results.

This article has some examples using the tool. The one that matches up with your approach uses a 3rd storage location to hold the logfile.

ddrescue -d -f -r3 /dev/sda /dev/sdb /media/PNY_usb/rescue.logfile

Click to expand...

1: if not in the directory try
/var
as most standard logs get written there.

2: I don't know about ddrescue so much, but in dd it will do whatever you say without a "force" command. Also if you have to stop and know how much has been read then you can do
dd if=/whatever/file of=/partial/image skip=number_of_bytes_already_read seek=number_of_bytes_already_read

Skip, "skips" a number of input bytes
Seek, "seeks to" an offset in the output file (so you don't overwrite what you've already read)

3: Not sure what that is, I usually use dd instead of dd rescue.

4: Yes you can mount the results. DD works linearly and all the partition info is at the head. If you have all the partition info then you can mount it. All bets are off for the data you care about, but you might get lucky.

Thank you both for your replies.

I was following a tutorial that unfortunately didn't mention the 3rd drive needed for the logfile

It's been 4 days and 2 of 3 tb have been recovered, however,that was done if the 1st 2 days.

If it continues at this rate, it might take about a year for the final TB of data

You might try the freezer trick to see if you can get the speeds to come back (for a bit). Also use seek and skip to avoid re-reading the same data/over writing what you have.

If there was a question on being able to stop and restart, you should open up another terminal (or some file browser) and navigate to where you launched the command and look for your log file.

If you see a file called "logfile" (based on the command issued in the OP) and it has any size to it, you probably have a valid one. You could then decide if you want to try something like stopping the process, copying the log file off to other media, doing the freezer trick mentioned above, and then resuming. It seems like you'd just have to reissue the command and point it at the logfile (even if you move it elsewhere) for it to resume.

Again - I've never played around with the command in question. You might try to setup a test environment and try some different things out. If you decide to stop, you could/should try to mount /dev/sdbx read-only to see if you have what you were looking for already.

Thank you both
I've decided to wait (not much of a choice) and it is now @ 2,855 GB
I'm guessing this is going to 3,000 or 3.072 ?
Who knows what then ?

orion23 said:

Thank you both
I've decided to wait (not much of a choice) and it is now @ 2,855 GB
I'm guessing this is going to 3,000 or 3.072 ?
Who knows what then ?

Click to expand...

If you get a valid image (may not be true if the drive is failing) you can just mount it and browse is as if it were a drive

mkdir /some/mount/point
mount recovery.dd /some/mount/point
ls /some/mount/point