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{{Short description|Computer internal interconnect architecture}}
{{about|the computer technology|the use of aircraft to combat wildfires|aerial firefighting}}
'''Fireplane''' is a computer internal [[interconnect]] created by [[Sun Microsystems]].
The Fireplane interconnect architecture is an evolutionary development of Sun's previous [[Ultra Port Architecture]] (UPA). It was introduced in October 2000 as the processor I/O interconnect in the [[Sun Blade (workstation)|Sun Blade 1000]] workstation, followed in early 2001 by its use in the [[Sun Fire]] and [[Sun Fire 15K]] series [[enterprise server]]s.<ref>{{Cite web
|title=SUN FIRE 4810 Midframe Server
|url=https://archive.icann.org/en/tlds/org/applications/unity/appendices/pdfs/sun/SunFire_4810.pdf
}}</ref> These coincided with the popular expansion of the [[World Wide Web|web]] in the [[dot com boom]] and a shift of Sun's main market from [[Unix workstation]]s to [[datacenter]] servers such as the [[Sun Starfire|Starfire]], supporting high traffic web sites.
Peak performance (in the Sun Blade 1000) reached 67.2&nbsp;GBytes/second or a sustained 9.6&nbsp;Gbit/s (2.4&nbsp;Gbit/s for each processor).<ref>{{Cite book
|title=System Performance Tuning
|author1=Gian-Paolo Musumeci
|author2=Michael Kosta Loukides
|publisher=O'Reilly Media
|year=2002
|isbn=059600284X
|edition=2nd
|pages=69–70
}}</ref>
Each generation of Sun architecture had involved upgraded processors and matching upgrades to the bus or interconnect architectures that supported them.<ref>{{Cite web
|title=The Sun Fireplane System Interconnect
|first=Alan
|last=Charlesworth
|url=http://www.sc2001.org/papers/pap.pap150.pdf
|year=2001
|publisher=ACM
|page=2
|access-date=2015-03-18
|archive-url=https://web.archive.org/web/20150402153007/http://www.sc2001.org/papers/pap.pap150.pdf
|archive-date=2015-04-02
|url-status=dead
}}</ref><ref name="Farrell" >{{Cite web
|title=The Sun Fireplane System Interconnect
|first=Ryan  |last=Farrell
|date=October 2005
|url=http://www.cs.umd.edu/class/fall2005/cmsc714/Lectures/farrell-SunFire-2up.pdf
|page=2
}}</ref> By this time, fast access to memory was becoming more important than simple CPU instruction speed for overall performance. [[Multiprocessor]]s, [[shared memory architecture|shared memory]], [[memory caching]] and [[uniform memory access|switching between CPU and memory]] were technologies necessary to achieve this.
The Sun Fire 15K series frame allows 18 combined processor and memory expander boards. Each board comprises four processors, four memory modules and I/O processors. The Fireplane interconnect uses 18×18 [[crossbar switch]]es to connect between them.<ref name="Oracle, 15k" >{{Cite book
|title=Sun Fire 15K/12K Systems Introduction
|section=1.3.1 Sun Fireplane Interconnect Architecture
|url=http://docs.oracle.com/cd/E19065-01/servers.12k/806-3509-13/1__Introduction.html
}}</ref> Overall peak bandwidth through the interconnect is 43&nbsp;Gbytes per second.
As memory architectures increase in complexity, maintaining [[cache coherence]] becomes a greater problem than simple connectivity. Fireplane represents a substantial advance over previous interconnects in this aspect.<ref name="Charlesworth, 3" >{{harvnb|Charlesworth|2001| page=3 }}</ref> It combines both [[snoopy cache]]<ref>{{Cite book
|title=PCI System Architecture
|page=Appendix A
|section=Snooping
|year=1995
|publisher=Addison-Wesley Professional
|isbn=0201309742
}}</ref> and point-to-point directory-based models to give a two-level cache coherence model.<ref>{{harvnb|Charlesworth|2001| page=1 }}</ref> Snoopy buses are used primarily for single buses with small numbers of processors; directory models are used for larger numbers of processors.<ref name="Farrell" /> Fireplane combines both, to give a scalable shared memory architecture.
Each expander board implements snooping across the board, with directory coherence across the interconnect. Each board is considered as a 'snooping coherence domain'. Small to mid-sized Fireplane systems, up to 24 processors, use a single coherence domain.<ref name="Charlesworth, 3" /> Larger systems with more processors use multiple coherence domains across their backplane interconnect.<ref name="Charlesworth, 3" /> Competing systems from makers such as [[Silicon Graphics International|SGI]] or the [[HP Superdome]] series<ref>{{Cite web
|title=HP Superdome White Paper
|publisher=Hewlett Packard
|date=September 2000
|url=http://www.hp.com/products1/unixservers/highend/superdome/pressroom/whitepapers/wp_superdome-technical.pdf
|archive-url=https://web.archive.org/web/20010612120713/http://www.hp.com/products1/unixservers/highend/superdome/pressroom/whitepapers/wp_superdome-technical.pdf
|archive-date=2001-06-12
}}</ref> use only a single level of coherency support and so require the more complex directory coherence to be used throughout.
Fireplane used for smaller servers and workstations is optimised for their single domain performance. They use an increased system clock by 50% to 150&nbsp;MHz. Snoops per clock cycle are also doubled from one half to one. Together these allow a snooping bandwidth of 150 million addresses per second.<ref name="Oracle, 15k" />
== References ==
{{Reflist|colwidth=35em}}
==External links==
* {{Cite journal
|url         = http://csdl.computer.org/comp/mags/mi/2002/01/m1036abs.htm
|title       = The Sun Fireplane Interconnect
|author      = Alan Charlesworth
|journal     = IEEE Micro
|date        = 2002
|volume = 22
|pages = 36–45
|archive-url  = https://web.archive.org/web/20070312013056/http://csdl2.computer.org/persagen/DLAbsToc.jsp?resourcePath=%2Fdl%2Fmags%2Fmi%2F&toc=comp%2Fmags%2Fmi%2F2002%2F01%2Fm1toc.xml&DOI=10.1109%2F40.988688
|archive-date = 2007-03-12
|doi         = 10.1109/40.988688
|url-status     = dead
}}
* {{Cite web
|title=Sun Fire 280R Server – Just the Facts
|publisher=Sun Microsystems
|date=September 2002
|page=16
|url=http://web.anl.gov/ECT/djs/green-network/sun-jtf-280r.pdf
}}
* {{Cite web
|title=Sun Fire 15K Server Redefines the High-end
|date=September 25, 2001
|url=http://www.taborcommunications.com/sponsors/sun/sunfire.html
|access-date=March 19, 2015
|archive-url=https://archive.today/20150319153712/http://www.taborcommunications.com/sponsors/sun/sunfire.html
|archive-date=March 19, 2015
|url-status=dead
}}
{{Sun Microsystems}}
[[Category:Computer-related introductions in 2000]]
[[Category:Sun Microsystems hardware]]
[[Category:Computer buses]]