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Xserve vs "Thumper"

When Apple's Xserve first came out it stood head and shoulders over the competition on every measure applicable in its markets - markets that were defined by the entertainment, education, and pre-press industries and therefore rewarded extensive optimization for image and streams processing. Thus Apple's Xserve was the first machine to introduce purpose specific RAID arrays made with truly cheap disks and optimized for continuous data flows, while later dual G5+ models offered multi-threaded support for up to four Altivec short array processors.

In August of 2004 I compared that original X-serve and Xraid storage combination to offerings from Sun and Dell to find the Apple product significantly faster and cheaper:

  Price Configuration
Apple X-Serve $4,399 2GB, 160GB, 2 x 2Ghz G5, unlimited users; MacOS-X
Dell 2850 $9,370 2GB, 2 x 73GB, 2 x 3.2Ghz Xeon, Windows 2003/XP Server 25 users
Sun V20Z $5,699 2GB, 2 x 73GB, 2 x Opteron 248, Solaris x86

That was then; today Apple has just announced completion of their Mactel conversion with the release to sales of pricing and specifications for their Xeon based Xserve and matching Xraid array.

Price out a processor broadly similar to that 2004 offering and it ends up costing quite a bit less - $3,647 for the 2Ghz Xeons today versus $4,399 for the dual G5 then. Note, however that the 2004 product had integrated connectivity and stood at the top of the performance heap while today's 2Ghz model is an entry level product lacking most of that integrated connectivity.

Thus a fairer comparison is based on complete, current, systems. Right now that means:

and lists for $37,137 - versus $26,400 for a dual G5 with two 3.5TB Xraids in 2004.

Of course, the new machine is a lot faster than the old one: four cores versus two, 16GB vs 2GB, internal SAS (and Xraid SATAII) versus ATA. All great, but the rest of the industry changed too, so these gains only contribute to Apple's strategic position if the product maintained Apple's G5 based technical lead over companies like Dell and Sun.

Unfortunately it doesn't: a similarly configured Dell SC1435 with four AMD opteron cores at 2.8Ghz, 16GB, and a 7TB Powervault MD1000 now costs only about $36,180 inclusive of the $3,299 Windows license.

In other words, Apple has gone from beating Dell on performance at about half Dell's price to roughly tying it on performance, but charging about a thousand bucks more.

At the time of my 2004 comparison Sun really didn't have a matching product - that V20z was really a workstation more than a server. Today, however, Sun has the leading product in the group: the X4500 "thumper" data server. Here's what you get for about $4,000 less than Apple what charges:

All for $32,995 at list - with 18TB more disk than Apple offers (but missing the two internal SAS drives in the XServe.)

But what about performance? Sun's CPUs are Opterons - combining lower power use with performance advantages over the Xeons on heavily multi-threaded code but losing to the Xeons on single threaded code. For most purposes, therefore the CPU issue is pretty much a wash right now (but only until AMD goes 65nm and raises the bar again).

As a result any general performance difference we're going to see has to come from comparing Apple's Xraid to the combination of ZFS with Thumper's six internal controllers.

Here's how Apple describes the Xraid's I/O capabilities:

Xserve RAID features dual 2Gb Fibre Channel ports for ultrafast data transport between the storage system and the host computer. Previously available only in high-end RAID systems, this industry-standard interconnect technology provides superior bandwidth, availability and deployment flexibility over earlier-generation SCSI technology. 400MB/s throughput

Each 2Gb Fibre Channel port offers 200MB/s bandwidth for a total throughput of up to 400MB/s. Fibre Channel is the only storage connectivity technology that provides guaranteed bandwidth, so the host computer receives data at the same high speed as the RAID system sends it out.

That's about where Dell puts their box too - and this sounds great except that Apple's other claims, noteably the ones pronouncing the Xeons five times faster than their G5+ predecessors on the basis of a non altivec enabled result - cast doubt on this one.

Sun's comparable marketing claim is that the maximum across all six controllers in the thumper can reach 2GBytes per second (five times Apple's claim) from disk to memory and about half that from disk to network.

I couldn't find real numbers on either Apple's new Xserve/Xraid combination or Dell's SC1435 with a PowerVault, but quite a lot of people have been benchmarking the ZFS/SATA combination on the X4500. Here's an example from a guy named Jason Hoffman who got this summary from a filebench run:

IO Summary: 5544761 ops 91746.2 ops/s, (29594/2961 r/w) 499.3mb/s, 60us cpu/op, 0.0ms latency

Hmm ? nearly ~100,000 operations/sec and a disc IO of ~500MB/sec.

My God.

That's 4Gbps.

Which is pretty good for a little, light benchmark.

In other words real results with the ZFS/X4500 combination easily exceed Apple's marketing claims - and you get two thirds more disk for $4,000 less.

So, bottom line, what's happened in the two and a half years since my earlier review? Mactel - with the result that Apple fell from leading the market on both price and performance to trailing the market on both price and performance.

The Apple press, of course, thinks the XServe Xeon a great success - but Apple went from market leading performance for less than Dell and Sun to market trailing performance for more than Dell and Sun; and, you know, With success like that, who needs failure?

Paul Murphy wrote and published The Unix Guide to Defenestration. Murphy is a 25-year veteran of the I.T. consulting industry, specializing in Unix and Unix-related management issues.