IBM Releases Redpapers on New POWER7 Servers

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Users now have access to detailed technical information on the world's most technologically advanced server platform.


IBM released a pair of "technical overview and introduction" Redpapers this week that detail the new line of POWER7 servers, information users will need to evaluate upgrades to POWER7.


The first Redpaper (REDP 4638-00) discusses the IBM Power 750 Express and Power 755 servers. The second (REDP-4639-00) discusses the IBM Power 770 and Power 780 units. Both Redpapers examine the servers in detail from a technical viewpoint—server architecture, energy utilization, virtualization capabilities, memory handling, and processor modes. The publications also take a close look at the architecture of the POWER7 processor, its ability to handle simultaneous multithreading, and memory access.


The Power 780 server has some unique new technology, and while it is the largest of the new POWER7 servers and therefore probably is going to appeal only to larger organizations, its new technology features make it even more newsworthy than its smaller siblings.


Summarizing and extracting some material directly from the Redpapers, we will try to give you an introduction to the unique features of the new Power 780. The server is unique because it has the ability to switch between a standard throughput mode and its unique TurboCore mode. Performance per core is boosted in TurboCore mode because the computer provides access to both additional cache and additional clock speed. Depending on the type of job it will be doing, the Power 780 can be booted in standard mode—otherwise known as MaxCore—or TurboCore. In MaxCore, the user can enable up to a maximum of 64 processor cores running at 3.86 GHz. In TurboCore mode, the user can enable up to 32 cores running at 4.14 GHz. Note that in TurboCore the server still has access to all available cache, which means that it will have twice the cache per core.


The Power 780 has 16 Double Data Rate 3 (DDR3) memory DIMM slots available per processor card; six hot-swappable 2.5-inch, small form factor, SAS or SSD disk bays per enclosure; one hot-plug, slim-line SATA media bay per enclosure (optional); redundant hot-swap AC power supplies in each enclosure; and a choice of integrated I/O options (one per enclosure)—quad 1 GB Ethernet, dual 10 GB optical and dual 1 GB Ethernet, or dual 10 GB copper and dual 1 GB Ethernet. The unit has one serial port, three USB ports per enclosure (max nine per system), two HMC ports per enclosure (maximum four per system), and eight I/0 expansion slots per enclosure (32 max per system). This is comprised of six PCIe 8x slots plus two GX++ slots per enclosure. It has dynamic LPAR support, processor and memory capacity upgrade on demand (CUoD), and PowerVM virtualization software. PowerHA high availability for AIX, IBM i, and Linux are optional, but most customers today are at least going with PowerVM, which allows for micro-partitioning. It includes Virtual I/O Server (VIOS), support for automated CPU and memory reconfiguration within dedicated and logical (LPAR) groups, and advanced features in the PowerVM Enterprise Edition. The Power 780 has various combinations of disk-only I/O drawers, depending on feature set. It comes with IBM Systems Director Active Energy Manager.


The Power 780 is configured with up to four separate enclosures that all work together. Each of the four contains one POWER7 processor card with two single 64-bit processors with up to eight cores containing 2MB of L2 cache (256 KB per core) and 32 MB of L3 cache (4 MB per core).


Note that while there are two types of processor cards on the Power 770, the Power 780 has only one type of processor card but two processing modes: the aforementioned MaxCore and TurboCore modes. (The Power 770 offers both a card with two six-core POWER7 single-chip modules (SCMs) and another with two eight-core SCMs. The six-core card runs at 3.5 GHz and has 48 MB of L3 cache while the eight-core card runs at 3.1 GHz and has 64 MB of L3 cache).


The POWER7 processor is essentially an eight-core processor. Part of the architecture allows for differing numbers of processor cores to be active. The processor can run with four cores, six cores, or the full eight cores operational. The L3 cache, however, is dependent upon the number of active cores—at least in MaxCore mode. So for a six-core version, there will generally be 24 MB of L3 cache available, and 16 MB for a four-core version. With TurboCore, a limited number of cores can access the full 32 MB of cache.


In standard or MaxCore mode, the Power 780 system uses all processor cores running at 3.86 GHz and has access to the full 32 MB of L3 cache. In TurboCore mode, only four of eight processor cores are available but run at a higher frequency, 4.14 GHz. So in TurboCore, the Power 780 has fewer cores running at a higher frequency. Because fewer cores are engaged, it now has a higher core-to-L3-cache ratio since all the cache is still available.


The point of offering both MaxCore and TurboCore modes is to optimize various workloads. Database workloads, for instance, are likely to benefit from very fast processors run at high transaction rates and high speeds. TurboCore utilizes four cores per POWER7 processor but continues to access the full 32 MB of L3 cache. This means each core has access to 8 MB of cache. For those applications that are licensed per core, TurboCore mode may dramatically save on software costs as well.


Workloads on the Web, on the other hand, will benefit from processes that have many threads to allow Web requests to be broken up into parts so that they can be processed in parallel. MaxCore provides up to eight cores and up to 32 threads per processor. The MaxCore mode is for workloads that benefit from a higher number of cores and threads handling multiple tasks simultaneously.


The Redpaper authors note that a breakthrough in material engineering and microprocessor fabrication enabled IBM to implement the L3 cache in embedded dynamic random access memory (eDRAM) and place it on the POWER7 processor die. This is significant for several reasons, according to IBM. There are improvements in latency, bandwidth, interface requirements, energy conservation (the on-chip eDRAM uses only 20 percent of the standby power of SRAM), and a smaller physical footprint.


The POWER7 processor includes intelligent energy features that help to dynamically optimize energy use and performance. Energy features in the processor work with IBM Systems Director Active Energy Manager software to dynamically optimize processor speed based on thermal conditions and system utilization.


There are many new and exciting features in the four new POWER7 servers. For those eager for technical detail and a clear explanation of the advanced technology in the POWER7 servers, you will want to read the IBM Redpapers.

Chris Smith

Chris Smith was the Senior News Editor at MC Press Online from 2007 to 2012 and was responsible for the news content on the company's Web site. Chris has been writing about the IBM midrange industry since 1992 when he signed on with Duke Communications as West Coast Editor of News 3X/400. With a bachelor's from the University of California at Berkeley, where he majored in English and minored in Journalism, and a master's in Journalism from the University of Colorado, Boulder, Chris later studied computer programming and AS/400 operations at Long Beach City College. An award-winning writer with two Maggie Awards, four business books, and a collection of poetry to his credit, Chris began his newspaper career as a reporter in northern California, later worked as night city editor for the Rocky Mountain News in Denver, and went on to edit a national cable television trade magazine. He was Communications Manager for McDonnell Douglas Corp. in Long Beach, Calif., before it merged with Boeing, and oversaw implementation of the company's first IBM desktop publishing system there. An editor for MC Press Online since 2007, Chris has authored some 300 articles on a broad range of topics surrounding the IBM midrange platform that have appeared in the company's eight industry-leading newsletters. He can be reached at



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