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Apple plays catchup with Nehalem EP-powered Xserves

But Mac servers still short on memory

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Apple has announced that it is delivering Intel's quad-core Xeon 5500 "Nehalem EP" processors in its Xserve server lineup starting today.

Apple jumped the gun on the Xeon 5500 launch by a few weeks, saying in early March it would add Nehalem EPs to the two-socket Mac Pro high-end PCs. That Apple is making a two-socket Xserve box available is noteworthy only because Mac shops, unlike Windows and Linux shops, are hitting a performance ceiling because Apple only sells two-socket machines.

Companies using Windows and Linux can move up their server makers' lines to four-socket machines, which adds between 60 and 100 per cent more oomph on various workloads, and if they need more memory, CPU, or I/O performance, there are a handful of companies (IBM, Unisys, and Sun Microsystems) that sell machines that scale up to 8, 16, or 32 sockets.

The two-socket Xserves are also, like their x64 brethren running Windows and Linux, constrained when it comes to memory capacity and bandwidth, and as we explained last week, memory bandwidth has more than tripled compared to the prior "Harpertown" Xeon 5400-based machines and on many workloads - after tuning performance for the new Nehalem features - are seeing a doubling of performance. By some metrics, the two-socket Nehalem EP servers are delivering about the same performance as a four-socket server using Intel's six-core "Dunnington" Xeon 7400 processors.

Suffice it to say, Xserve customers have been waiting for a significant performance boost for quite a while, and today they got it.

The Xserve machines Apple is shipping today can be equipped with one quad-core 2.26 GHz Xeon E5520 in a base configuration, and larger setups with two of these E5520s or two 2.66 GHz X5550s or two 2.93 GHz X5570s. The lower speed Nehalem EP chips burn 80 watts of juice, while the faster ones burn 95 watts. Apple is not shipping low-voltage L5506 or L5520 quad-core parts (which run at 60 watts), is not shipping the E5502 dual-core part, and doesn't seem to be too interested in the high-end W5580 part, which runs at 3.2 GHz and which burns at 130 watts. Apple has dropped a number of other possible Xeon 5500 SKUs just to keep its sales simpler.

All of the Xeon 5500 processors used in the new Xserves have 8 MB of L3 cache and HyperThreading simultaneous multithreading; while not all of the Xeon 5500s support the Turbo Boost function, which allows the clock speed of a chip to be cranked up if the thermals of the machine allow it, all of the Xeon 5500 chips that Apple is selling in its servers are supporting it. On the 2.93 GHz X5570s, Turbo Boost allows the speed of the core to be stepped up to 3.33 GHz, thermals permitting.

Apple is supporting only 1.07 GHz DDR3 main memory in the Xserves, even though faster 1.33 GHz is available. Each server has six memory slots per processor socket, which should mean that the machine supports up to 48 GB of main memory when fully loaded with 4 GB DDR3 DIMMs and double that to 96 GB with 8 GB DIMMs (which other server makers are touting but not quite shipping yet in all cases).

However, with Mac OS X Server v10.5, Apple warns that the Nehalem EP Xserves will only be able to support a maximum of 32 GB of main memory. And the company is only selling machines that use 2 GB DDR3 DIMMs right now, limiting maximum memory to 24 GB. Hopefully, the "Snow Leopard" Mac OS X v10.6 release, perhaps due in early June at Apple's annual Worldwide Developers Conference, will break through that memory barrier up to 96 GB and beyond with both hardware and software. If Apple wants to virtualize Mac OS X workloads - and allow customers to add Windows and Linux virtual machines to their machines if they so choose - then the Xserve machines will need larger main memory capacity. It is that simple.

Like prior Xserve machines, the Nehelam EP version has three hot-plug disk drive bays. Apple supports 160 GB and 1 TB 7,200 RPM SATA drives as well as a 450 GB 15K RPM SATA drive in these bays. RAID disk mirroring support is built into Mac OS X Server and there is an optional RAID 5 disk controller for the drives. Customers who want solid state disks can also buy a 128 GB SSD for these disk bays, which can radically improve I/O performance. In terms of I/O, the new Xserve has two PCI-Express 2.0 x16 slots, two Gigabit Ethernet ports, two FireWire 800 ports, and two USB ports. The machine comes with an nVidia GeForce GT120 graphics card with 256 MB of graphics memory.

A base configuration of the new Xserve comes with a single quad-core 2.26 GHz Nehalem EP chip, 3 GB of memory, a 160 GB SATA drive, and an unlimited client edition license to Mac OS X Server v10.5; it costs $2,999. Adding a second quad-core Xeon E5520 processor bumps the price up to $3,599. Loading this machine up to two 2.93 GHz X5570 processors, 24 GB of memory, two 1 TB hard disks and one 128 GB SSD (which sells for $500), and redundant 750-watt power supplies rockets the price up to $12,149. ®

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