Originally Posted By: uc50ic4more
WD has a Purple range that is supposed to be designed for always-on operation for servers. The prices are about the same as the Blue range.
As blu mentioned, you do not want to use purple drives for NAS setups. Right from WD's site:
Recommended use
WD Purple storage is tested and recommended for use in surveillance and security systems up to 8 bays and optimized for 32 HD cameras. For additional surveillance capacity, look at WD datacenter hard drives. WD Purple is not recommended for use in NAS environments, please consider using WD Red hard drives for desktop RAID and NAS environments or WD datacenter hard drives for rackmount or large RAID configurations.
A reviewer explained the reason why here:
THE REASON FOR THIS IS BELOW
The A/V drives ignore errors, the normal drives will do an error recovery to attempt to get back any data from the platter.
When recording video (security cameras etc) you want an A/V drive that will just record whatever you throw at it, and keep going even if it misses a byte or two. An error in a couple of bytes just causes a minor blip in the video stream, but the rest won't stop. On a normal drive it could go into an error recovery mode and stop recording for 10-30 seconds - and this is much worse for security.
However if you store documents, a single byte error could corrupt megabytes or even gigabytes of important data.