On 5/13/2014 12:14 AM, Franc Zabkar wrote:
The fix could be incorporated into ddrescue, or it could be
implemented as a small helper application. However, it requires a
little knowledge of WD's Vendor Specific Commands, or access to
certain commercial tools.
If someone would be willing to write this tool, I would be only too
willing to help, but only if the code were open source and freely
available to all. The procedure is extremely simple and the code would
be very small. In fact I could perform the required task with a small
MHDD batch routine.
If I can ever find the time again to get back to my ddrutility
programming for more than just bug fixes and get caught up, I may likely
take up things like this. I have some really good things I was working
on, but have not been able to pursue them lately.
But I think I need to work on getting a "donate" button on my site (will
be working on this very soon), because when I am finally ready to
release the good stuff, I think at least one item might become a bit
popular. Except for Mac users... Mac users will be SOL as the good stuff
only works in Linux, sorry.
Maybe I am really trying to encourage myself with this to try to make
some time, but here are a few teasers:
Did you know that some newer drives have the ability to change the error
timer? This is the amount of time a drive will spend when a read error
is encountered, which can easily take 2-4 seconds per error. On some
drives it may be able to be changed to as low as 1/10th second which can
turbo charge a recovery first pass, although it does increase the number
of errors when used which can somewhat offset the benefit.
Ever heard of the elusive, controversial, and now twice obsolete read
long command? Ever found any freeware that can actually perform it
successfully? I haven't. How would one know if it was useful or just
overrated if they did not have the ability to try it for themselves?
Did you know the Linux kernel does excessive retries when read errors
are encountered? As ddrescue is universal it uses normal reads so it
suffers from this, although there are usually a few less retries when
using the direct option. It is possible to bypass this behavior for much
increased error processing performance using special pass-through
commands. I am sure no one would be interested in a patch for ddrescue
that would allow it to process errors 5 times faster, would they?
I have said too much...
P.S.
I will not get into any conversations here about any of this, except
maybe the ddrescue patch as it is directly related, but only to a point.
This is Antonio's place for ddrescue and I am just responding to the
post. If you wish to discuss anything else I have mentioned above,
please post in the ddrutility discussion on sourceforge or email me
directly.
Scott
_______________________________________________
Bug-ddrescue mailing list
[email protected]
https://lists.gnu.org/mailman/listinfo/bug-ddrescue
