Re: [Bug-ddrescue] (Not-a-bug) just question about 520-bytes-perfectly drives

[Scott Dwyer]

It is curious the amount of interest I have seen recently in 520 byte 
per sector drives. To clear some things up, Linux is more or less (more 
on the more side) hard coded for 512 bytes per sector, although it can 
handle multiples of that such as 4096 byte advanced format drives. But 
it will never be able to process 520 byte per sector drives directly. 
The only way is to use the SCSI passthrough, which is what sg_raw does. 
It is even difficult to locate commercial software that can clone or 
image such drives (although I am about to change that :) ).

But did everyone forget my older passthrough patches for ddrescue? They 
are still available in the downloads section for ddrutiltiy on 
sourceforge. A smart person could possibly hack the patch and 
potentially make a version of ddrescue that could read those drives. Not 
an easy task, but possible. It is the same concept that I am using in my 
own software to access the drives.

Happy programming :)

Scott


On 6/18/2018 1:24 PM, Oleg Krutov wrote:
> Hello!
>
> Is it physically possible to read data from SAS/SCSI drives that have more
> than 512 (usually -- 520) bytes per sector? These drives are not properly
> detected by kernel ("Unsupported sector size 520. 0 512-byte logical
> blocks"), so it can be read only via sg_raw utility by direct scsi
> commands, by little chunks and very slowly. Maybe there is an opportunity
> to read a drive "more directly" than with O_DIRECT flag?
>
> Thank you!
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