blocksize 4096 even for floppy and CDROM?

blocksize 4096 even for floppy and CDROM?

[JPT]

Hi,

sorry for bothering. I fear I need help by a block device pro ;)

I try to read several bad floppies and DVDs using safecopy.

I wonder why safecopy always says
Reported hw blocksize: 4096
Reported low level blocksize: 4096

even if the medium is floppy (512) or CDROM (2048)

is this a kernel issue always assuming min 4k block size?

Does anybody have an idea if there is a Unix out there that doesn't have
this limitation?

or which Linux version dropped support for smaller sectors?

Or is this simply safecopy's fault?


thank you very much for your help.

Jan

Re: blocksize 4096 even for floppy and CDROM?

[Randy Dunlap]

[adding the linux-block mailing list]


On 2/22/22 12:08, JPT wrote:
> Hi,
> 
> sorry for bothering. I fear I need help by a block device pro ;)
> 
> I try to read several bad floppies and DVDs using safecopy.
> 
> I wonder why safecopy always says
> Reported hw blocksize: 4096
> Reported low level blocksize: 4096
> 
> even if the medium is floppy (512) or CDROM (2048)
> 
> is this a kernel issue always assuming min 4k block size?
> 
> Does anybody have an idea if there is a Unix out there that doesn't have
> this limitation?
> 
> or which Linux version dropped support for smaller sectors?
> 
> Or is this simply safecopy's fault?
> 
> 
> thank you very much for your help.
> 
> Jan

-- 
~Randy

Re: blocksize 4096 even for floppy and CDROM?

[Martin K. Petersen]

Randy,

>> I wonder why safecopy always says
>> Reported hw blocksize: 4096
>> Reported low level blocksize: 4096
>> 
>> even if the medium is floppy (512) or CDROM (2048)
>> 
>> is this a kernel issue always assuming min 4k block size?

Not sure how safecopy queries the block size. The kernel supports
devices with 512, 1024, 2048, and 4096-byte logical blocks.

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: blocksize 4096 even for floppy and CDROM?

[JPT]

Hi,

seems that safecopy always assumes 4096, while ddrescue always assumes 512.
you have to specify the blocksize manually for both programs.

thanks

Jan


Am 23.02.22 um 05:00 schrieb Martin K. Petersen:
>
> Randy,
>
>>> I wonder why safecopy always says
>>> Reported hw blocksize: 4096
>>> Reported low level blocksize: 4096
>>>
>>> even if the medium is floppy (512) or CDROM (2048)
>>>
>>> is this a kernel issue always assuming min 4k block size?
>
> Not sure how safecopy queries the block size. The kernel supports
> devices with 512, 1024, 2048, and 4096-byte logical blocks.
>