InfoWorld review: Intel Xeon Nehalem-EX lives large

Blurring the lines
One of the major differences between x86/x64 servers and most RISC servers and mainframes is the ability of higher-end RISC platforms to handle error detection, correction, and recovery at the system level. This is not a matter of simply determining that a DIMM has gone bad and displaying the location of the failure, but automatically blocking off that memory segment and permitting the DIMM to be hot-swapped with another, then resuming normal operations with the replacement without any downtime. The MCA (Machine Check Architecture) in the Nehalem-EX provides this capability, as well as other enhanced reliability features.

Providing these features isn't as simple as it may sound. The OS needs to play a significant part in this dance too, since the processor needs to inform the operating system of a RAM failure and allow the OS to either restart a process that was using that memory or otherwise shuffle data away from the bad RAM prior to isolation and replacement.

There's also support in the Nehalem-EX for hot-add RAM and CPUs, meaning that RAM and processors can be added on the fly to an existing system without a reboot. Naturally, this also requires close communication with the operating system and firmware to enable, so don't expect these features to be available on older OS platforms, though most major operating system vendors have said they will support these features at the processors' release.

There are more RAS features too, such as QPI packet retry and QPI CRC checking that bolster the reliability of QuickPath Interconnects, I/O hub hot-add, and memory thermal throttling. Suffice it to say, Intel has thrown a whole bunch of extremely high-level reliability functions into the new Xeon.

Although the Nehalem-EX doesn't offer the fastest clock rates, it offers more cores per CPU than any other Intel processor, it can address massive amounts of RAM, and it adds a whole host of reliability features -- features previously only found in the Itanium. We'll soon see what AMD's just-arrived Magny Cours can deliver, but whatever the outcome, it's clear that x86/x64 computing has never been better.

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This story, "InfoWorld review: Intel Xeon Nehalem-EX lives large," was originally published at InfoWorld.com. Follow the latest developments in servers, processors, and other hardware at InfoWorld.com.