Storage on the Outside of a HDD Yields Faster IO?

I was talking to a guy last week about SATA II and he mentioned that if you create a partition on the outside of a SATA drive you can boost the performance by 50%.

This sounds like an urban legend. Tailrank doesn’t need a lot of disk but we need FAST seeks…. hacks like this seem like an interesting idea.


Destroking seems to be the term here. Seagate has a PDF which talks about it but doesn’t go into much depth:

Some IT departments may attempt to meet their online application needs with 10K SAS drives, employing unorthodox techniques to wrest improved performance from them. For example, they might deploy lower-capacity drives to ensure each drive accesses less data, thus lowering drive access times. In effect, these departments would be purchasing more actuators to simultaneously access their data.

Or they may resort to storing data only on the outer diameter of the disc, a practice referred to as short-stroking (or destroking). This reduces the distance the actuator must move to access the data, thus improving disc seek time at the cost of severely limiting effective capacity.

  1. He’s talking about destroking or “short stroking” a disk. “Boost the performance” = “reduce track-to-track latency”, not “increase throughput”. Basically, if you can localize data that will be accessed together to a small set of contiguous tracks, then you reduce the total distance the disk heads have to travel on average during random I/O.

  2. OK.. wait… how is this different than just having a contiguous block ANYWHERE on the disk? I don’t understand why it needs to be on the edge….

  3. There are more bytes/track on the outside of the disk, so you use fewer tracks and, now that I think about it, you also get higher transfer rates on the outside of the disk.

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