Re: Sector size in and out suggestion and question

[Antonio Diaz Diaz]

Hi Lucian,

Lucian Maly wrote:
> I would like to make a suggestion to add another option of sector
> (hardware block) size of output device and differentiate it from
> already existing --sector-size for input device - e.g.:
> --sector-size-in=bytes
> --sector-size-out=bytes

I think your problem has nothing to do with sector size. ddrescue by default 
reads and writes 64 KiB blocks, not single sectors.


> Disk /dev/sdb: 2.7 TiB, 3000558944256 bytes, 732558336 sectors
> Units: sectors of 1 * 4096 = 4096 bytes
> Sector size (logical/physical): 4096 bytes / 4096 bytes
> I/O size (minimum/optimal): 4096 bytes / 4096 bytes
> Disklabel type: dos
> Disk identifier: 0x000246c6
> Device     Boot Start       End   Sectors  Size Id Type
> /dev/sdb1         256 732558335 732558080  2.7T  7 HPFS/NTFS/exFAT
>
> Disk /dev/sdc: 3.7 TiB, 4000752599040 bytes, 7813969920 sectors
> Units: sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 4096 bytes

It seems that the 3 TB of data in /dev/sdb1 have been copied. I think the 
problem is that a whole drive can't be copied to another drive with a 
different sector size because then the number of sectors stored in the 
partition table make an incorrect partition size in the destination drive.

Probably you should have partitioned /dev/sdc beforehand and then copy 
/dev/sdb1 to /dev/sdc1.

> Device     Boot Start       End   Sectors   Size Id Type
> /dev/sdc1         256 732558335 732558080 349.3G  7 HPFS/NTFS/exFAT
>
> Question1: Is there any way to fix that now without running it again?

Probably, if you manage to resize /dev/sdc1 without modifying its start 
position.

> Question2: How do you currently specify destination sector size? It
> does not seem to be possible - no mentioning of that in your manual.

Specifying the destination sector size would have no effect. The problem is 
of incorrect data, not of incorrect sector size. The first sector of 
/dev/sdb can't be copied to /dev/sdc and expect it to work.


> Many thanks for your great work,

You are welcome.

Best regards,
Antonio.