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Old 01-09-2010, 02:33 AM
Valmor de Almeida
 
Default is ddrescue this slow?

Hello,

I am trying to recover data from a failed drive. An initial attempt with dd took over 12 hours and it was not even at half of the 80GB damaged drive; so I quit. Info on the web pointed me to ddrescue


*** ddrescue -n /dev/sda /dev/sdc rescued.log

which has taken over 6 hours so far

Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:******** 0 B,* errsize:****** 0 B,* errors:****** 0

Current status
rescued:*** 58656 MB,* errsize:** 4408 kB,* current rate:**** 4096 B/s
** ipos:*** 58660 MB,** errors:***** 32,*** average rate:*** 2958 kB/s
** opos:*** 58660 MB,**** time from last successful read:****** 0 s

Copying non-tried blocks...

The "current rate" varies and sometimes is down to a few B/s!
Is this normal? The drive copied to is a USB external drive.

Thanks for inputs.

--
Valmor
 
Old 01-09-2010, 06:20 AM
Valmor de Almeida
 
Default is ddrescue this slow?

On Sat, Jan 9, 2010 at 3:33 AM, Valmor de Almeida <val.gentoo@gmail.com> wrote:


Hello,

I am trying to recover data from a failed drive. An initial attempt with dd took over 12 hours and it was not even at half of the 80GB damaged drive; so I quit. Info on the web pointed me to ddrescue



*** ddrescue -n /dev/sda /dev/sdc rescued.log

which has taken over 6 hours so far

Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:******** 0 B,* errsize:****** 0 B,* errors:****** 0


Current status
rescued:*** 58656 MB,* errsize:** 4408 kB,* current rate:**** 4096 B/s
** ipos:*** 58660 MB,** errors:***** 32,*** average rate:*** 2958 kB/s
** opos:*** 58660 MB,**** time from last successful read:****** 0 s


Copying non-tried blocks...

The "current rate" varies and sometimes is down to a few B/s!
Is this normal? The drive copied to is a USB external drive.

Thanks for inputs.

--
Valmor





It's about 10 hours now since it started and here it is

Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:******** 0 B,* errsize:****** 0 B,* errors:****** 0

Current status
rescued:*** 58763 MB,* errsize:* 22918 kB,* current rate:*** 1376 kB/s
** ipos:*** 58786 MB,** errors:***** 66,*** average rate:*** 1751 kB/s
** opos:*** 58786 MB,**** time from last successful read:****** 0 s

Copying non-tried blocks...

Sometimes the "current rate" reads 0 B/s for a long time... and "time from last successful read" can be 8m.

Would any one know whether this is normal?

Thanks,


--
Valmor
 
Old 01-09-2010, 08:23 AM
Neil Bothwick
 
Default is ddrescue this slow?

On Sat, 9 Jan 2010 07:20:18 +0000, Valmor de Almeida wrote:

> Sometimes the "current rate" reads 0 B/s for a long time... and "time
> from last successful read" can be 8m.
>
> Would any one know whether this is normal?

Doesn't ddrescue retry on blocks it cannot read? That would explain the
variable read rate, even the period of zero activity. If your drive is
that badly damaged, dd would have been no use anyway.


--
Neil Bothwick

There's too much blood in my caffeine system.
 
Old 01-09-2010, 10:10 AM
Stroller
 
Default is ddrescue this slow?

On 9 Jan 2010, at 09:23, Neil Bothwick wrote:

On Sat, 9 Jan 2010 07:20:18 +0000, Valmor de Almeida wrote:


Sometimes the "current rate" reads 0 B/s for a long time... and "time
from last successful read" can be 8m.

Would any one know whether this is normal?


Doesn't ddrescue retry on blocks it cannot read? That would explain
the

variable read rate, even the period of zero activity. If your drive is
that badly damaged, dd would have been no use anyway.


I think Valmor is using GNU ddrescue, with which one makes the
multiple passes manually. The "-n" flag on the command line that
Valmor posted (`ddrescue -n /dev/sda /dev/sdc rescued.log`) relates to
the examples given in the GNU manual page [1]. I believe that GNU
ddrescue is the better version - it was inspired by garloff's original
work, and makes improvements, but it operates differently.


Having said that, it could just be that the drive _firmware) is making
multiple attempts to read the failing blocks before returning the
failure (or the data, in the case that a 2nd attempt to read the drive
was successful) to the host o/s. Isn't this how hard-drives work?


ddrescue worked fast here when I tried it here recently on a drive
with only one unreadable block, but Valmor's drive is failing much
more severely. TBH, I would expect reads from a badly-failing drive,
but this is an intuitive expectation, not a reasoned one. I think the
best thing he can do is hold his breath, wait until its finished and
see how if the results are readable, after running `fsck` on the
mounted filesystem.


Valmor: when I ran the `ddrescue -dr3` stage I had no success at all,
however the system was fine after a reboot & a `chkdsk`. Better than
it had been, in fact, on the old hard-drive. You might have more luck
getting *some* of the blocks showing as failed when you run it on your
drive, but don't be too disheartened if you don't.


Stroller.




[1] http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Examples
 
Old 01-09-2010, 02:25 PM
Grant Edwards
 
Default is ddrescue this slow?

On 2010-01-09, Neil Bothwick <neil@digimed.co.uk> wrote:
> On Sat, 9 Jan 2010 07:20:18 +0000, Valmor de Almeida wrote:
>
>> Sometimes the "current rate" reads 0 B/s for a long time... and "time
>> from last successful read" can be 8m.
>>
>> Would any one know whether this is normal?
>
> Doesn't ddrescue retry on blocks it cannot read?
>
> That would explain the variable read rate, even the period of
> zero activity. If your drive is that badly damaged, dd would
> have been no use anyway.

Yes. On a disk with a lot of bad blocks it can be very slow as
it retries bad blocks and narrows the failed regions.

--
Grant
 
Old 01-10-2010, 01:08 AM
Valmor de Almeida
 
Default is ddrescue this slow?

On Sat, Jan 9, 2010 at 11:10 AM, Stroller <stroller@stellar.eclipse.co.uk> wrote:



On 9 Jan 2010, at 09:23, Neil Bothwick wrote:


On Sat, 9 Jan 2010 07:20:18 +0000, Valmor de Almeida wrote:




Sometimes the "current rate" reads 0 B/s for a long time... and "time

from last successful read" can be 8m.



Would any one know whether this is normal?




Doesn't ddrescue retry on blocks it cannot read? That would explain the

variable read rate, even the period of zero activity. If your drive is

that badly damaged, dd would have been no use anyway.




I think Valmor is using GNU ddrescue, with which one makes the multiple passes manually. The "-n" flag on the command line that Valmor posted (`ddrescue -n /dev/sda /dev/sdc rescued.log`) relates to the examples given in the GNU manual page [1]. I believe that GNU ddrescue is the better version - it was inspired by garloff's original work, and makes improvements, but it operates differently.




Indeed I am using GNU ddrescue and the -n flag is supposed to expedite the recovery of data as posted in http://www.cgsecurity.org/wiki/Damaged_Hard_Disk


"The best solution - both faster and more efficient - seems to be Antonio Diaz's 'ddrescue'
(ddrescue)"


# first, grab most of the error-free areas in a hurry:
./ddrescue -n /dev/old_disk /dev/new_disk rescued.log
# then try to recover as much of the dicy areas as possible:
./ddrescue -r 1 /dev/old_disk /dev/new_disk rescued.log



expectation, not a reasoned one. I think the best thing he can do is hold his breath, wait until its finished and see how if the results are readable, after running `fsck` on the mounted filesystem.


The first step above finished; don't know how long it took but it was a long time (maybe 20 hours or more?) and the screen output was

Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:******** 0 B,* errsize:****** 0 B,* errors:****** 0

Current status
rescued:*** 58811 MB,* errsize:* 48909 kB,* current rate:****** 83 B/s
** ipos:*** 58860 MB,** errors:***** 95,*** average rate:*** 1365 kB/s
** opos:*** 58860 MB,**** time from last successful read:****** 0 s

Copying non-tried blocks...
ddrescue: write error: Input/output error


Comparing with the screen output at the time of my first post,

Current status rescued went from 58656 MB to 58811 MB, errsize went from 4408 kB to 48909 kB.


Don't know how the write error: Input/output error message affect the data in the new drive copied to. Not sure whether I should do the next step with option -r 1.

This failed drive is still bootable and the corruption is in the partitions /var (which I do not care) and /home; these cannot be mounted. I would like to attempt to get a couple of files from /home that were not in the most recent backup. Maybe I should try to rescue only the partition /home. However this partition is under LVM. Specifically, /dev/sda4 is a linux LVM partition. The volume group is vfda and the logical volume of interest is /dev/vfda/home which has reiserfs file system. Is it possible to rescue data only from this partition when under LVM?


*



Valmor: when I ran the `ddrescue -dr3` stage I had no success at all, however the system was fine after a reboot & a `chkdsk`. Better than it had been, in fact, on the old hard-drive. You might have more luck getting *some* of the blocks showing as failed when you run it on your drive, but don't be too disheartened if you don't.




Stroller.





Stroller, you mean your rescue.log showed no problematic entries? I got over 400 lines in my rescue.log file.

root@sysresccd /root % head rescued.log
# Rescue Logfile. Created by GNU ddrescue version 1.11

# current_pos* current_status
0xDB45D9000**** ?
#***** pos******* size* status
0x00000000* 0x9CE341000* +
0x9CE341000* 0x00000200* -
0x9CE341200* 0x0001F000* *
0x9CE360200* 0x00000200* -
0x9CE360400* 0x00020000* *

0x9CE380400* 0x3BD63AC00* +

*

Thanks for inputs.

--
Valmor
 
Old 01-10-2010, 01:45 AM
Valmor de Almeida
 
Default is ddrescue this slow?

On Sat, Jan 9, 2010 at 11:10 AM, Stroller <stroller@stellar.eclipse.co.uk> wrote:

[snip]
*



in the GNU manual page [1]. I believe that GNU ddrescue is the better version - it was inspired by garloff's original work, and makes improvements, but it operates differently.

Comment. Another reason I moved away from dd (apart from the slow running time) to ddrescue was because of this note related to LVM.


http://www.inference.phy.cam.ac.uk/saw27/notes/backup-hard-disk-partitions.html
"Steve Holmes reports that dd with conv=sync,noerror doesn't correctly
image disks with LVM2 Logical Volumes. I haven't investigated this. He also
points out GNU ddrescue (
not
the same as dd_rescue mentioned above) which looks useful. According to
Steve, ddrescue works finewith LVM2, and some
people seem to suggest it's
generally superior to dd_rescue."

The partition I would like to get data from is under LVM (previous post).

Thanks,

--
Valmor
 
Old 01-10-2010, 07:09 AM
Stroller
 
Default is ddrescue this slow?

Would love to comment on this. Is it possible you could resend this post in plain text format?
Stroller.

On 10 Jan 2010, at 02:08, Valmor de Almeida wrote:On Sat, Jan 9, 2010 at 11:10 AM, Stroller <stroller@stellar.eclipse.co.uk> wrote:

On 9 Jan 2010, at 09:23, Neil Bothwick wrote:
On Sat, 9 Jan 2010 07:20:18 +0000, Valmor de Almeida wrote:

Sometimes the "current rate" reads 0 B/s for a long time... and "time
from last successful read" can be 8m.

Would any one know whether this is normal?

Doesn't ddrescue retry on blocks it cannot read? That would explain the
variable read rate, even the period of zero activity. If your drive is
that badly damaged, dd would have been no use anyway.

I think Valmor is using GNU ddrescue, with which one makes the multiple passes manually. The "-n" flag on the command line that Valmor posted (`ddrescue -n /dev/sda /dev/sdc rescued.log`) relates to the examples given in the GNU manual page [1]. I believe that GNU ddrescue is the better version - it was inspired by garloff's original work, and makes improvements, but it operates differently.


Indeed I am using GNU ddrescue and the -n flag is supposed to expedite the recovery of data as posted in http://www.cgsecurity.org/wiki/Damaged_Hard_Disk

"The best solution - both faster and more efficient - seems to be Antonio Diaz's 'ddrescue' (ddrescue)"

# first, grab most of the error-free areas in a hurry:
./ddrescue -n /dev/old_disk /dev/new_disk rescued.log
# then try to recover as much of the dicy areas as possible:
./ddrescue -r 1 /dev/old_disk /dev/new_disk rescued.log


expectation, not a reasoned one. I think the best thing he can do is hold his breath, wait until its finished and see how if the results are readable, after running `fsck` on the mounted filesystem.

The first step above finished; don't know how long it took but it was a long time (maybe 20 hours or more?) and the screen output was

Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued:******** 0 B,* errsize:****** 0 B,* errors:****** 0
Current status
rescued:*** 58811 MB,* errsize:* 48909 kB,* current rate:****** 83 B/s
** ipos:*** 58860 MB,** errors:***** 95,*** average rate:*** 1365 kB/s
** opos:*** 58860 MB,**** time from last successful read:****** 0 s
Copying non-tried blocks...
ddrescue: write error: Input/output error
 
Old 01-10-2010, 10:03 AM
Dale
 
Default is ddrescue this slow?

This help? Should be plain text.


Dale

:-) :-)

Stroller wrote:
Would love to comment on this. Is it possible you could resend this
post in plain text format?


Stroller.


On 10 Jan 2010, at 02:08, Valmor de Almeida wrote:



Indeed I am using GNU ddrescue and the -n flag is supposed to
expedite the recovery of data as posted in
http://www.cgsecurity.org/wiki/Damaged_Hard_Disk


"The best solution - both faster and more efficient - seems to be
Antonio Diaz's 'ddrescue' (ddrescue
<http://savannah.gnu.org/projects/ddrescue/>)"


# first, grab most of the error-free areas in a hurry:
./ddrescue -n /dev/old_disk /dev/new_disk rescued.log
# then try to recover as much of the dicy areas as possible:
./ddrescue -r 1 /dev/old_disk /dev/new_disk rescued.log




expectation, not a reasoned one. I think the best thing he can do
is hold his breath, wait until its finished and see how if the
results are readable, after running `fsck` on the mounted filesystem.


The first step above finished; don't know how long it took but it was
a long time (maybe 20 hours or more?) and the screen output was


Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 0 B, errsize: 0 B, errors: 0
Current status
rescued: 58811 MB, errsize: 48909 kB, current rate: 83 B/s
ipos: 58860 MB, errors: 95, average rate: 1365 kB/s
opos: 58860 MB, time from last successful read: 0 s
Copying non-tried blocks...
ddrescue: write error: Input/output error
 
Old 01-10-2010, 05:09 PM
Valmor de Almeida
 
Default is ddrescue this slow?

On Sun, Jan 10, 2010 at 8:09 AM, Stroller <stroller@stellar.eclipse.co.uk> wrote:

Would love to comment on this. Is it possible you could resend this post in plain text format?
Stroller.


Below is my last post copied and pasted into gmail without the html hot links. I am doing this from within systemrescuecd using firefox and gmail. Don't know how to make it plain ascii otherwise. Hopefully just eliminating the html links will work. Stroller, is this what you are referring to?


Thanks,

--
Valmor
*


On Sat, Jan 9, 2010 at 11:10 AM, Stroller* wrote:

[snip]
*




in the GNU manual page [1]. I believe that GNU ddrescue is the better
version - it was inspired by garloff's original work, and makes
improvements, but it operates differently.

Comment.
Another reason I moved away from dd (apart from the slow running time)
to ddrescue was because of this note related to LVM.


h
* * http://www.interference.phy.cam.ac.uk/saw27/notes/backup-hard-disk-partitions.html


"Steve Holmes reports that dd with conv=sync,noerror doesn't correctly
image disks with LVM2 Logical Volumes. I haven't investigated this. He also
points out GNU ddrescue (
not
the same as dd_rescue mentioned above) which looks useful. According to
Steve, ddrescue works finewith LVM2, and* some people seem to suggest it's
generally superior to dd_rescue."

The partition I would like to get data from is under LVM (previous post).

Thanks,

--
Valmor
**
 

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