Logical vs. physical blocks on various media and how to detect

Peter Van Hove peter at Smart-Projects.net
Wed Oct 12 00:40:37 PDT 2011

* From the T10 Reflector (t10 at t10.org), posted by:
* "Peter Van Hove" <peter at smart-projects.net>
Hi Keiji,
> 1. DVD, BD have EDC on each 2K logical sector
> So they have a lager ECC block size (32K, 64K) but may report 
> uncorrectable
> error on each sector by sector. Some important information such as file 
> system
> may use only a 2K logical sector. So MMC devices should ignore error in 
> other
> remaining sectors in the ECC block.
This I did not know !
So on DVD and BD, a logical 2K sector may be unreadable, but another 2K 
sector in that same ECC (physical) block may still be readable ?
So if block x is unreadable, blocks x-1 and x+1 may very well still be 
readable ?
That actually completely shakes my understanding of reading physical vs 
logical blocks.
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