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Testing Participants

As we were writing this review we recalled a small island of Sipadan located near Borneo. This island is the top of a very high cliff that rises up from a depth of 600-700 meters. It is in fact a cliff column about 1500 meters in circumference and rising a little above the sea level. In its top part the cliff is circled with a 50m high live coral reef. The vertical coral walls are the distinguishing feature of the island.

This island, a pearl of Malaysia, offers best places for diving, particularly the Barracuda Point. There are many, very many barracudas there. Indeed, there are thousands of them in there!

Just imagine you are hanging somewhere between the sea surface and the blue abyss. Thousands of fish are spiraling all about you. And then they come… Swift and relentless killers. And you realize there’s only a thin layer of the water costume’s rubber separating you from the hostile environment and there are thousand of wary eyes and jaws around you… Catch your breath now but beware, there’ll be a lot of barracudas in this review, too. We’ll start out with the largest and most dangerous of them!

Seagate Barracuda 7200.10

The table below lists the whole Barracuda 7200.10 series that comprises as many as 25 different models that differ in the interface and cache buffer size as well as in the number of platters and heads. They share one thing in common, though. They all use the perpendicular recording technology (for details on perpendicular recording technology see our article called Seagate Momentus 5400.3 160GB Hard Disk Drive with Perpendicular Recording Technology).

You can note that the right branch of the family tree is shorter by one limb. Seagate decided not to make a 250GB ATA model with a 16MB cache buffer. Well, the user is their judge…

Theoretically, the use of perpendicular recording should have considerably increased the areal density and given Barracuda 7200.10 drives an unheard-of speed of linear reading. Let’s see what speed is provided by the ST3750640AS model that has the highest areal density in the Barracuda 7200.10 series:

It is almost 80MB/s – an astonishing speed indeed!

But the graph has a queerly straight shape. Could Seagate have abandoned adaptive formatting on the transition to perpendicular recording? In theory, such disks should have a reserve in areal density. Let’s check it out. Here’s the zone map for the disk:

So, adaptive formatting is still here. Each head has its own zone distribution. The diagram shows two graphs that reflect the zone distribution for the best and worst heads. In the zero zone, the difference between the surfaces in terms of sectors per track is 110 sectors, which is a big enough difference.

Note also the number of tracks – there are almost 150 thousand of them on the ST3750640AS’s platters!

 
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