Storage Devices and RAID for A+

This A+ topic covers technician-level recognition and selection of common storage devices, storage form factors and interfaces, removable/portable media, and the basic RAID levels used in typical installation and upgrade scenarios. The focus is on identification, compatibility checks, and simple tradeoff decisions (performance vs cost vs redundancy). This topic explicitly excludes deep filesystem administration, SAN/NAS architecture design, backup policy design, and RAID controller configuration/management.

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5 lessons in this topic

HDD vs SSD Storage Basics

Recognize the basic differences between hard disk drives and solid-state drives and choose the better fit for a simple use case.

Storage Form Factors & Interfaces

Distinguish storage form factor from interface and avoid common compatibility mistakes such as confusing M.2 with NVMe itself.

Flash, Optical & Removable Storage

Recognize common removable or portable storage types and match them to straightforward support scenarios.

RAID Levels & Tradeoffs

Recognize RAID 0, 1, 5, and 10 and choose the level that best matches a simple performance or redundancy requirement.

Storage Selection & Installation Logic

Make practical storage choices by checking capacity, form factor, interface support, and whether RAID is appropriate for the requirement.

Common mistakes to avoid

Technicians often conflate form factor and interface (e.g., assuming a 2.5" device is always an SSD). Another confusion: assuming an SSD always yields maximum speed regardless of the interface (a SATA SSD is limited by SATA bandwidth; an NVMe SSD requires NVMe...

Learners often say "M.2 equals NVMe" or "all small drives are NVMe". Another frequent mistake is assuming that physical fit guarantees full performance (for example, putting an NVMe drive into an M.2 slot that lacks enough PCIe lanes).

Treating optical media as common modern install media or assuming all devices can read any memory card without an adapter.

Confusing RAID 5 as having no performance cost-parity imposes write overhead. Mixing up RAID 10 and RAID 0+1: while related, RAID 10 requires mirrored pairs that are striped and provides clearer rebuild behavior.