Saving a little power by writing to SSD first?

May 16, 2017
20
2
UK
Hi,

My new set-up storage-wise consists of a 128GB SSD and a 2TB WD Purple HDD, and currently 2 cameras (about 6MP in total) recording continuously. I've read on here (and it seems logical), that there's no performance gain in writing video to the SSD first, so I just used that for system disk and BI Db, and I write the video / image files directly to HDD.

I have been wondering though, if it might be worth writing to the SSD first to save a little bit of power. At the moment, I assume both the SSD and HDD are constantly active, the SSD writing to its DB directory, and the HDD writing video/image files. The SSD currently has 75GB free. If I set my "New" area to be on SSD, set the size limits to say 50GB, after which they get moved to "Stored" on the HDD, then this would surely mean that only the SSD is in constant use. The HDD would get chance to to go idle, and just be woken up occasionally to transfer some files. It looks like I'm producing about 120GB of files a day, so the HDD would only be woken around twice a day, for I reckon less than 20m.

Looking at the WD Purple spec sheets, I see the 2TB one drops from 4.4W (higher for bigger drives) to 0.4W when it sleeps. That seems like a power / heat saving worth having. I assume the SSD won't use much more power for the somewhat more constant writing, and I believe the SSD write cycles lifetime thing is less of an issue these days.

I'd be grateful to hear any thoughts. If people don't point out any obvious flawed thinking, I may look to experiment and record the power usage over time...
 
In case you're interested, SanDisk wrote a lengthy but informative 'white paper' (=> here <=) that extols the virtues of using SSDs also for storage of the video files.
 
I have been wondering though, if it might be worth writing to the SSD first to save a little bit of power.

The amount of money saved would be negligible. The added wear and tear to the HDD from the constant temperature changes could be significant.

A WD Purple uses about 6W of power when it's active. According to the Energy.gov calculator, using that much power 24/265 would cost an "average" of $5.26 a year. Personally I don't think maybe saving $5 is worth the risk of maybe killing your hard drive off faster.