The Best Hard Drive For Surveillance Is...

"It depends."

At least according to Tom's Hardware, which just released their test results benchmarks of WD's Purple and Seagate Surveillance hard drives.

Overall, deciding between the Purple and the Surveillance HDD comes down to your application. With fewer than eight drives, under a known read/write workload, the WD Purple stands out. Going beyond eight drives with a write-only workload definitely favors the Seagate Surveillance HDD. In both cases, the two drives offer great surveillance performance, exceeding what you'd see from mainstream desktop drives, while selling for far less than their enterprise-class siblings.

This qualification seems silly, however, as most surveillance systems are predominantly write-intensive, since most users rarely search for video, seemingly making Seagate the best choice overall.

It's also worth nothing that these tests were performed using benchmarking tools, not with actual cameras or even real video streams, so no real world performance issues were discussed.

WD Purple for Small Systems

One other key point in these tests: According to WD, the Purple line is not intended for rack mount use, only small drive count standalone systems:

Specific to the Purple, WD suggests no more than eight in a system, and they're not intended for rack-mount applications. This is mainly due to a lack of Rotary Acceleration Feed Forward (RAFF), a technology that overcomes the effects of vibration introduced by other drives in an enclosure. In server applications, where dozens or hundreds of drives can share the same rack, RAFF is necessary. Clearly, WD doesn't believe that functionality is required for the Purple's target market.

Readers may see our original overview of WD Purple and Seagate Surveillance drives for more background.

"It's also worth nothing that these tests were performed using benchmarking tools, not with actual cameras or even real video streams, so no real world performance issues were discussed"

So this is a "Surveillance Hard Drive Shoot-Out" without using surveillance cameras? OK.

In the article they used a utility provided by Western Digital that is supposedly designed to mimick surveillance camera throughput, with emphasis on large block writes and very little reads. The writer said they vetted the software to make sure they didn't try to skew results, but true they did not get actual cameras to do the testing.

The funny part of the article were the comments at the end with some in almost child like wonder going "ohhh, I want to put together a surveillance system now", and a number of posts speculating why SSD's might be a good consideration for surveillance.

Gee, an awful lot of the drive's specific workload is determined by the design of the recording software being used as well as the architecture of the recording system. Not all recording software lays down the video in the same way. Not all recording systems use drives the same way.

Small single drive or JBOD systems usually introduce other workloads on top of writing video to disk. An OS, a database for recording motion data or analytics data, etc. A multi-drive array is a different animal than is being simulated in this study as well.

We can all agree video surveillance drives are write intensive. Benchmarks that show good throughput are valuable. But I'm not sure this kind of study really tells me anything about how these drives are going to perform in my particular application.

Drive selection in commercial products tends to be

1. Does it have the overall throughput to meet my needs? (where back-of-the-envelope type numbers are a good start)

2. Does it have the right industrial characteristics (i.e, heat, mechanicals, power, etc)?

3. Does it have the right warranty?

4. Is it the right price?

Qualify, test (with your software!), monitor return rates, repeat.