Tag: fdisk

DD_RESCUE ( GDDRESCUE’s ddrescue ) for disks with Advanced Format ( AF ) 4KiB sectors 4096 byte

Posted on by Yazeed

1- Before using dd, ddrescue, or dd_rescue, you need to know which disk is which, you can do that by simply using the command “fdisk -l” in my case, the old disk turned out to be /dev/sdb and the new un-partitioned disk is /dev/sdc.

So, i have been cloning a 2TB hard drive ( WD20EARS ) to a WD20EARX, same disk, but with a few differences

WD20EARS is sata 2 and the other is sata 3, another difference is that using “hdparm -I /dev/sdb” the older WD20EARS reports (And should not be true)

WD20EARS

Logical/Physical Sector size:           512 bytes

wile with “hdparm -I /dev/sdc” the newer WD20EARX reports

        Logical  Sector size:                   512 bytes
        Physical Sector size:                  4096 bytes
        Logical Sector-0 offset:                  0 bytes

The first clone did not work for a reason unknown to me, i cloned my NTFS disk with ddrescue (gddrescue) on a linux (because i don’t know how to clone on windows) and then plugged it into windows, where it simply did not work, and in disk management reported the disk as un-partitioned space, so now i want to do the thing again, but i don’t want that slow performance, so i increased block size to 4KiB. (UPDATE: THE NEW COPY WITH 4KiB DID WORK BUT I DONT KNOW IF THE 4KiB SIZE IS RELEVANT, MAYBE YOU SHOULD TAKE A LOOK AT THE SECOND DIFFERENCE BETWEEN THE DISKS UP AT THE BEGINNING OF THE POST)

For now, i will try the cloning with the command (Only change the block level for advanced format hard drives)

Note, block size no longer works, and it is called sector-size, but the short letter for it -b is still the same, so we will change this to the line below it
ddrescue --block-size=4KiB /dev/sdb /dev/sdc rescue2.log
ddrescue -b=4KiB /dev/sdb /dev/sdc rescue2.log

And if all of your data is important, you can ask ddrescue to retry every bad block 3 times (or as many times as you wish) with the -r command

ddrescue --block-size=4KiB -r3 /dev/sdb /dev/sdc rescue2.log
ddrescue -b=4KiB -r3 /dev/sdb /dev/sdc rescue2.log

And what do you know, the disk now works on my WINDOWS machine 😀 no errors and no nothing, great, so now to some details about the copy

The result up to now is that i am reading at a maximum of 129MB while the average (in the first 60 GBs is 93018 kB/s), if this continues, i will be done in less than 6 hours.

The part that does not make any sense to me is that western digital states clearly in the specs that the maximum (Host to/from drive (sustained)) is 110 MB/s for both drives, it must be that i need to wait a bit more and see what that actually means.

rescued:         0 B,  errsize:       0 B,  errors:       0
Current status
rescued:    74787 MB,  errsize:       0 B,  current rate:     119 MB/s
   ipos:    74787 MB,   errors:       0,    average rate:   93018 kB/s
   opos:    74787 MB,     time from last successful read:       0 s
Copying non-tried blocks...

Now, once done, you can have the OS reload the partition table without having to restart, you can simply use the command partprobe

partprobe
or
partprobe /dev/sdc

To use partprobe, you need to install parted

apt-get install parted

If it were a linux drive, an advanced format drive would not have it’s first sector on sector 63 but rather on sector 2048, which is at exactly 2KiB, it could (but usually does not) start at any other value divisible by 8.

Windows probably does something similar for our AF Disk, so asking parted about our ntfs disk, this is what parted says

Model: ATA WDC WD20EARS-00M (scsi)
Disk /dev/sdb: 2000GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start   End     Size    Type     File system  Flags
 1      1049kB  2000GB  2000GB  primary  ntfs

1049kB is 1074176 bytes, Which when divided by 8 is 134272 (divisible by 8).

NOTES:
-There is a tool specifically for cloning ntfs volumes called ntfsclone, i am not sure what extra features it provides that are specific to ntfs, i have never used it before, with my disk that has bad blocks, i can only rely on gddrescue.
-A block is 512 on regular drives, and 4096 on newer ones, if you want to backup the hard drive’s geometry, you can do one of the following
Backup the first 63 blocks (MBR + Bootloader). on a “non advanced format” drive

dd if=/dev/sda of=/mnt/storage/sda.vbr bs=512 count=63

On an advanced format drive, we can try

dd if=/dev/sda of=/mnt/storage/sda.vbr bs=4096 count=63

Which, will make us read 258048 bytes rather than the traditional 32256 bytes (around 250K rather than 32K)