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USB/SCSI-2 interface chip ?

Started by Robert Lacoste May 23, 2012
Dear all,
We are looking for an USB to SCSI-2 bus interface chipset. Not a ready-made 
interface cable, but either a dedicated bridge chip (I'm afraid they no 
longer exist...) or a microcontroler/FPGA with the associated firmware SCSI 
stack. Any available reference design or commercial solution somewhere, or 
should we start from scratch, which is of course possible but quite long ? 
Custom host-side drivers would not be a huge problem in that case.
Thanks,
Robert
www.alciom.com


On 23/05/12 18:54, Robert Lacoste wrote:
> Dear all, > We are looking for an USB to SCSI-2 bus interface chipset. Not a > ready-made interface cable, but either a dedicated bridge chip (I'm > afraid they no longer exist...) or a microcontroler/FPGA with the > associated firmware SCSI stack. Any available reference design or > commercial solution somewhere, or should we start from scratch, which is > of course possible but quite long ? Custom host-side drivers would not > be a huge problem in that case. > Thanks, > Robert > www.alciom.com > >
That's an odd requirement - parallel SCSI was never particularly popular, and SCSI-2 was outdated before USB 2.0 came on the scene (if I've got my history right). I doubt if a dedicated bridge chip ever existed for something like that. Are you looking for a one-off solution? I would think the realistic solution is to put together an embedded PC card with a SCSI interface card, running Linux, and pass the disk on as an iSCSI disk on the network rather than USB.
David Brown <david.brown@removethis.hesbynett.no> writes:
>On 23/05/12 18:54, Robert Lacoste wrote: >> Dear all, >> We are looking for an USB to SCSI-2 bus interface chipset. Not a >> ready-made interface cable, but either a dedicated bridge chip (I'm >> afraid they no longer exist...) or a microcontroler/FPGA with the >> associated firmware SCSI stack. Any available reference design or >> commercial solution somewhere, or should we start from scratch, which is >> of course possible but quite long ? Custom host-side drivers would not >> be a huge problem in that case.
>That's an odd requirement - parallel SCSI was never particularly >popular, and SCSI-2 was outdated before USB 2.0 came on the scene (if >I've got my history right). I doubt if a dedicated bridge chip ever >existed for something like that.
?? Parallel SCSI never popular? Where were you? It was huge in the PC server, workstation (back when they were separate than desktops), and RISC server markets, with almost total penetration? There are many commercial USB to SCSI bridges you can buy. Unfortunately, they are all old designs, based on chips that have long since been end-of-lifed. (ie. I think Prolific had one. Maybe Oxford Semi, etc). The OP is looking for a still current maker, which may be quite a no-go.

"Doug McIntyre"  a &#2013265929;crit dans le message de groupe de discussion : 
4fbd6e9d$0$74663$8046368a@newsreader.iphouse.net...
>The OP is looking for a still current maker, which may be quite a no-go.
That's exactly the problem... I guess that there is no longer any active USB-to-SCSI2 chip available, but we were hoping that someone has already developped that on an FPGA or ARM micro, to replace such a chipset. There are still plenty of old SCSI peripherals that some customers want to keep using... Robert
On 24/05/2012 01:11, Doug McIntyre wrote:
> David Brown<david.brown@removethis.hesbynett.no> writes: >> On 23/05/12 18:54, Robert Lacoste wrote: >>> Dear all, >>> We are looking for an USB to SCSI-2 bus interface chipset. Not a >>> ready-made interface cable, but either a dedicated bridge chip (I'm >>> afraid they no longer exist...) or a microcontroler/FPGA with the >>> associated firmware SCSI stack. Any available reference design or >>> commercial solution somewhere, or should we start from scratch, which is >>> of course possible but quite long ? Custom host-side drivers would not >>> be a huge problem in that case. > >> That's an odd requirement - parallel SCSI was never particularly >> popular, and SCSI-2 was outdated before USB 2.0 came on the scene (if >> I've got my history right). I doubt if a dedicated bridge chip ever >> existed for something like that. > > ?? Parallel SCSI never popular? Where were you? It was huge in the PC > server, workstation (back when they were separate than desktops), and > RISC server markets, with almost total penetration? >
I meant relative to the alternative - IDE/ATA - parallel SCSI was of limited popularity. It had, as you say, almost total penetration in particular markets for a while, but it was still only a tiny percentage of the total disk market.
> There are many commercial USB to SCSI bridges you can buy.
Judging from the history (with SCSI-3 in 1996, SAS in 2001, and USB 2 in 2000) I would have thought that parallel SCSI-2 would be well out of date before USB disk adaptors started becoming popular. Based on the relatively low number of parallel SCSI (rather than SAS) installations still in use since USB 2 became mainstream, and the low percentage of those that would be interested in a USB-SCSI adaptor (think about the use-cases - they are much less than for USB-IDE or USB-SATA), I find it surprising to think that it would be worth making such a bridge chip at all. Of course, if you know of such devices, then I'll just have to be surprised!
> Unfortunately, they are all old designs, based on chips that have > long since been end-of-lifed. (ie. I think Prolific had one. Maybe > Oxford Semi, etc). > > The OP is looking for a still current maker, which may be quite a no-go. >
David Brown <david@westcontrol.removethisbit.com> writes:
>Judging from the history (with SCSI-3 in 1996, SAS in 2001, and USB 2 in >2000) I would have thought that parallel SCSI-2 would be well out of >date before USB disk adaptors started becoming popular.
Just because the spec was out, doesn't mean everything instantly cut over. I was buying parallel SCSI based servers well into 2006-2007 timeframe.
>relatively low number of parallel SCSI (rather than SAS) installations
I'd have to say that parallel SCSI installations far outnumbered SAS given how many years it was available.
>Of course, if you know of such devices, then I'll just have to be surprised!
I can't find one *in stock*, and I can't find the one I have here to see what chip is in it. But there are store listings for them.. http://www.buy.com/prod/cables-to-go-usb-to-scsi-2-adapter-cable-type-a-male-usb-hd-50-male/10264492.html http://www.allwaytech.com/catalog/index.php?main_page=product_info&products_id=660http://www.alibaba.com/product-gs/417916645/Cables_To_Go_USB_To_SCSI.html