[svlug] Failing external drive. Planning to DD the failing drive to new external drive. Help please

[Michael Eager]

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On 11/12/2015 10:15 AM, H P Ladds wrote:
>
>
> On Thu, Nov 12, 2015 at 11:26 AM, Michael Eager <eager at eagercon.com <mailto:eager at eagercon.com>> wrote:
>
>     On 11/12/2015 07:44 AM, H P Ladds wrote:
>     > I have an external hard drive failing and hope to DD the drive to a new external hard drive.
>
>     You should not use dd to copy data from one disk partition to another.
>     Use rsync, cpio, tar, or cp.
>
>
>     > Should I reformat the new drive to ext3 (or ext4) before DDing?
>
>     Assuming that the new drive is identical to the old drive,
>     however you format the partition on new drive, when you copy the old
>     partition to the new one using dd, the format will be replaced
>     by the format of the partition on the old drive.  In fact, there is
>     no need to format the drive when you use dd to copy a partition.
>     (But, as I said, don't use dd.)
>
>     > The failing drive has two 500 gig partitions (I believe ext3). Should I DD the partitions separately
>     > or DD the entire drive?
>
>     Using dd to copy from one disk to a disk with a different size or
>     organization is unlikely to work.  At best, you will lose space.
>     At worst, the drive will be unmountable.
>
>
> So true...
>
> Partitioning the new hard drive with two 600G partitions, not formatting the partitions and then...
>
> dd if=/dev/sdh3 of=/dev/sdi2
>
> resulted in an umountable drive /dev/sdi2
>
> "wrong fs type, bad option, bad superblock on /dev/sdi2,
>         missing codepage or helper program, or other error
>         In some cases useful info is found in syslog - try
>         dmesg | tail  or so"
>
>     > After DDing I'll try to retrieve the data. Oh and it is all data, no OS.
>
>     If you want to use dd, you can create an image of the failing drive on
>     a spare drive, mount the image using the loopback device, and copy from the
>     image to your final destination using rsync.  This is sometimes useful if
>     the old drive is failing, so you have to make multiple copies using dd.
>
>     --
>     Michael Eager eager at eagercon.com <mailto:eager at eagercon.com>
>     1960 Park Blvd., Palo Alto, CA 94306 650-325-8077 <tel:650-325-8077>
>
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>


-- 
Michael Eager	 eager at eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077