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The Complete Handbook of Hard Drive Arrays
A practical reference for professionals, businesses, and serious enthusiasts who design, deploy, and maintain storage systems that actually work
by Alumigogo Books
Chapter 1: Understanding Hard Drive Arrays
When we talk about a hard drive array, we're talking about taking multiple physical disk drives and making them act as a single, logical storage unit. The whole point of doing this is to solve a fundamental problem: a single drive is a single point of failure, and its performance and capacity are fixed. An array is a way to mitigate that risk and build a storage system that's larger, faster, or more resilient than any single disk could be on its own.
Consider a concrete example. A video editor has a 1 TB drive holding a project they're working on. The drive is full, so they buy a second 1 TB drive and copy the project to it. Now they have two drives with the same data. They've created a very simple array, a mirror, where the logical result is still a 1 TB volume, but the data exists on two physical drives. This has no performance benefit for writing, but the read performance can be improved because data can be read from either disk. More importantly, if one drive dies, the other holds a complete copy. No data is lost.
This is the essence of the array. It's not a product category in the sense of a specific gadget, but a method of combining components to achieve a goal. The most common implementation is a RAID array, but the concept is broader. A Just a Bunch Of Disks, or JBOD, is an