SUMMARY: SWIS/S v. SunSwift cards

From: Donn MacCara (
Date: Mon Mar 17 1997 - 15:38:32 CST

Thanks to all who responded. Everyone agrees that the SWIS/S is more
expensive and of course does not have the ethernet function. Some
people have obtained better performance using the SWIS/S when several (4
or more disks ) are attached, though one response suggests the
performance difference only shows up if you are using the ethernet
function as well. There is a conflict if you use both SWIS and SunSwift
on the the same machine. (See below for Bugid # and workaround.)
Original question:

I want to attach a Sun Multipack ( 7 x 2.1 GB disks ) to an Ultra 2
server. I am told, and it makes sense, that it should be attached to a
dedicated fast/wide SCSI interface.

Sun sells both a SWIS/S (f/w SCSI) and a SunSwift ( f/w SCSI + 10/100 Mb
ethernet). The SunSwift is slightly less expensive, but I can not find
any difference between the two cards as far as SCSI specifications are

Even though I do not need the extra ethernet, is there any reason (e.g.
performance) to choose the SWIS/S card over the SunSwift card?

The Responses:
I'm not sure which sun cards you are comparing, but if one of them
  is the X1062A, then the biggest difference is DIFFERENTIAL. The
  SunSwift card is Fast/Wide/SINGLE-ENDED, and the X1062A is

  Hope this helps,


I had the same situation here. The only issues are:

1) SWIS/S and SunSwift card have an interoperability problem. Use all
of one
or the other.

2) The SWIS/S card has problem in systems with hme ethernet interfaces.
same problem as its DWIS/S cousin) Its easy to work around.

Add these lines to /etc/system

* Begin BUGID 1261590
set hme:hme_64bit_enable=0
set fas:fas_enable_sbus64=0
* End BUGID 1261590

Btw, I have Ultra 2's with SWIS/S cards and the 12 drive MultiDisk Pack.

Had same config and same dillema. I asked Sun Express and the reason is
that they are trying to discontinue the earlier product and push for
the newer, that is why the high price on the old one.

I had no use for the ethernet part but hey!


I just bought a SunSwift card it works great. I think one limitation is
that it's only supported
by Solaris 2.X. But it's a better value card.


We looked at each of these products as well. As I recall, the SWIS/S
is an "intelligent" SCSI host adapter, meaning that it offloads some
of the I/O processing from the CPU onto the SBus card. The SunSwift
does not do this -- the CPU handles most of the I/O. I believe that
translated to roughly 20-30% less work for the CPU using the SWIS/S

That would explain the cost difference -- the SWIS/S is just capable
of doing more.

This is from (somewhat fuzzy) memory. You may want to check with your
Sun Engineer for verification...
The performance of both cards is exactly the same if you use only the
interface. If you start using the ether interface on the swift, then
may find that SCSI perf is affected. It's up to you, performance or the
convenience of a spare ether interface.


           We are in exactly the same situation and I would be keen to hear any
summary. (Our order went in on Thursday so the piont is now academic for
us ;)
Accroding to our Sun sales man the SWIS/S has some inbuilt smarts
and can slightly reduce the load on your cpu. They estimated an extra 5%
load on
one cpu if we went with a SunSwift.

In your case, I'd go with the dedicated card. The SunSwiftcard is
a RISC chip that the SWIS/S card has. Without this chip the
card performs badly under hight I/O loads. It only takes 4 disks for
performance to begin dropping off noticeably - as much as 30%.

Get the SunSwift. There is a problem with SWIS/S card running in a
I tried to add a SWIS/S card to an Ultra 2 that already had a SunSwift
and my machine kept panicinig. I called SUN tech support and they told
me that there was a bug with the isp firmware on SWIS/S cards.
Their work around was to turn off 64 bit mode or only use the fas
firmware which comes on SWIS/S card. I traded my SunSwift card in for a
SWIS/S card and now my machine work great and I added 3 more disk.

Thanks to:

 "Robert D. Worsham" <>
 "Matthew Stier" <> (G. Dimitoglou)
 "Cheng, Bruce" <>
 "Michael R. Zika" <>
 Francis Liu <>
 "Palmai, Zoltan (zspa)" <>

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