NAS / NAS Pro

Hard drive manufacturers design drives that will perform well for their largest customers, or sets of customers. This is why “classes” of drives exist.

Design Expectations

The information below is a high-level set of expectations the drive manufacturers have when designing, testing, and selling “NAS and NAS Pro” drives.

Power On Hours	24 hrs/7 days (8760 POH)
Write / Read Ratio	60/40
Block Sizes	Random
Seek Profile	80% Random / 20% Sequential

Design Details

Performance needs are in balance with cost. NAS usage may include: a RAID file system, 24/7 usage, data backup, multiple drives in one chassis, file sharing, OS/remote desktop or virtual machine hosting, and media streaming.
NAS drives are built to be more tolerant of adjacent drives in the chassis, run longer, and be more reliable than desktop client drives, and are tuned specifically for small systems using RAID technology.

While NAS drives are technically capable of performing in a data streaming environment, they are not tuned for this and may be under an undetectable form of stress as they attempt to keep in sync with the expectations of the host.
If your system is primarily a media server, you would be better off using AV/surveillance class drives. NAS class drives are designed for small systems using 4 or fewer drives.

NAS Pro Drives

While also tuned for NAS systems, the NAS Pro basically represents a higher quality drive that is intended for medium to large business use (above 8 drives per chassis), where the NAS drive would be recommended for home and small business (8 or fewer drives per chassis).

Drive Comparison Table

The table below is an excerpt from the HDSTOR Drive Comparison Table, which shows features (or lack thereof) of the different classes of drives, as well as relative performance, reliability, and cost.

	Network Attached Storage	NAS Pro
Production Screening?	YES	YES
Rated for 24/7 Use?	NO	YES
Fixed Shaft Spindle?	NO	YES
RV Feed Forward Sensors?	NO	YES
Time Limited Retry Tables?	YES	YES
Workload Rating	MEDIUM	HIGH
Firmware Tuning	Random Access/ RAID	Random Access/ RAID
Performance Capabilities	MEDIUM	MEDIUM
Reliability Ratings	MEDIUM	HIGH
Cost	MEDIUM	HIGH