[nmglug] Check a disk?

Nick Frost nickf at frostitute.com
Mon Mar 25 18:46:33 PDT 2013

On 03/25/2013 07:37 PM, John Osmon wrote:

> On Mon, Mar 25, 2013 at 06:56:34PM -0600, Bob Knight wrote:
>> ddrescue rules. I got a disk from a macbook back for son-in-law - it
>> was well and truly hosed. Just be patient.
> Indeed -- rule it does.
> dd (from whence ddrescue sprang) has been one of my best friends for
> at least two decades.  I recommend that *everyone* practice its use
> for those times you *really* need it.  Try:
>   - cloning a disk
>   - cloning a partition
>   - pulling out the MBR from a disk
> All this and more awaits those that take the time to learn the powerful
> tools that are available from un*x-like OSes...

While we're on a roll....has anyone seen funny issues with using dd for
cloning SSD's?  With some SSD's when a bootable OS is installed (e.g.
Ubuntu) a clone with dd fails;

dd if=/dev/sda of=/dev/sdb bs=1M

whereas adding this;

dd if=/dev/sda of=/dev/sdb bs=1M conv=notrunc,noerror

works? Since MLC's aren't linear I'm wondering if anyone else has
experience with this sort of thing? I guess I'm asking since SSD's are
becoming increasingly commonplace, and data recoveries on
them...especially if TRIM is in use...e.g. "ext4
discard,errors=remount-ro" are likely a nightmare.



Nicholas S. Frost
7 Avenida Vista Grande #325
Santa Fe, NM  87508
nickf at frostitute.com

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