[rescue] IDE SSDs? I never knew...

[Mike Spooner]

I feel that HDD Emulator is fair, rather than SCSI Emulator.

- Mike

On 28 June 2024 15:20:30 BST, Dave McGuire via rescue <rescue at sunhelp.org> wrote:
>On 6/28/24 10:04, Jonathan Chapman via rescue wrote:
>>> Another is that they don't talk directly to the hardware; they speak
>>> some other disk interface protocol, such as SATA, out the other side.
>> 
>> Moreover, they are often talking to something FAT32 formatted, and storing the SCSI targets as files. They can also be CD-ROMs, Ethernet adapters, etc.
>> 
>> Compare to an ACARD SCSI to IDE [to SATA] bridge, where you talk to the disk 1:1 w.r.t. blocks. Those are closer to a host interface bridge, IMO. More like a HVD <-> LVD bridge than whatever you want to call the modern iterations.
>> 
>> I think calling something like the BlueSCSI, ZuluSCSI, SCSI2SD, etc. an "emulator" is probably not wrong.
>
>  Most if not all SCSI hard drives have a processor on them, frequently an i80186 or an Hitachi SuperH.  What gets stored on the platters is completely opaque, and in many cases contains error control information, block remapping data, etc etc, i.e. a lot more than end-user data. There may be some form of filesystem involved, who knows?  But even that term has a loose definition.
>
>  The interface to the platters is something very different from SCSI. Somewhere there's a dividing line between "analog" and "digital", but the line where it becomes "SCSI" is a good bit further in the same direction.  Nearly all SCSI hard drives store data in an RLL format. The SCSI layer is unaware of it.
>
>  My point is, there's always stuff going on under the hood.  The difference here is that with a ZuluSCSI or similar, we can see what's under the hood.  So it's an SD card, something that we recognize as being also available for other applications.  Does that make the whole assemblage an "emulator"?  No.  It's not emulating a SCSI mass storage device, it IS a SCSI mass storage device.  Not an emulation, but an implementation.
>
>               -Dave
>
>-- 
>Dave McGuire, AK4HZ
>New Kensington, PA
>
>
>_______________________________________________
>rescue list - http://sunhelp.org/mailman/listinfo/rescue_sunhelp.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sunhelp.org/pipermail/rescue_sunhelp.org/attachments/20240630/57fd3ec9/attachment.html>