SUMMARY: sBus I/O Boards - slots, population

From: Caparrosso, Nelson T. (
Date: Fri Aug 18 2000 - 11:23:28 CDT

Thanks very mucho to the early replies.

The boards are called Dual-SBus boards because of the two SBus channels
going into the UPA backplane. I got confused as I thought the "slots"
correspond to the SBus "channels", apparently, the 3 "SBus slots" plus the
other on-board "slots" (FC GBIC, FAS, Hme) somehow are allocated in some
way to the 2 SBus channels. No one could confirm whether which of the 3
"available slots" allocate to which SBus channel.

Regarding Question 2: For purposes of redundancy and avoidance of board
saturation, it is best to spread FC-AL I/O adapters among all the boards.
Apparently, each SBus I/O board only has a 120MB/sec bandwidth and having 2
- 100MB/sec device adapter in a single board could easily saturate it.

Many thanks for enlightening me with this issues...


> -----Original Message-----
> Esteemed Gurus:
> Just a tech question on sBus I/O boards of EXXXX enteprise servers -
> what's the maximum no. of sBus slots on each board? I noticed that each
> board has three slots but these boards (as well as prtdiag) are called
> 'Dual-SBus? Are the middle slots not sBus slots? Should they not be
> populated with I/O cards? Is there a reason why I/O contollers use mostly
> the left and right slots and not the middle slot?
> Second Question: Is it optimally better to distribute Fibre Controllers
> among different I/O boards or populate the first board first then go on
> the next, etc...?
> As always, TIA and I will simmarize...
> ------------------------------------------------------------------
> UNIX/Microsoft/GIS Consultant
> Decision Consultants, Inc
> Internet :
> Disclaimer: All views & opinions in this e-mail are mine alone!
> ------------------------------------------------------------------

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