HDD and SSD Power-On-Hours (POH) and MTBF

[Doombot1]

Hello!

I just recently build a PC with a whole bunch of drives in it. I have 4 500GB HGST Deskstars (used, about 63.3K hours each from Craigslist), a Samsung 950 PRO SSD, and a 4TB Seagate Barracuda (new as of a year ago when I purchased it), among a few other unimportant drives. I have my computer set to turn off the drives after a certain amount of time (as per the default Windows 10 settings). However, after only slightly more than a year, my SSD is already showing 9K hours and my 4TB HDD is showing about 7.5K (I bought it a few months after the SSD). The HGST drives, all four of which I am using in a RAID-1+0 array, I am just using as reference. They had about 63,275 hrs. when I bought them three days ago. Now, they have about 63,350 hours each. Meaning, that they aren't actually turning off when my PC hibernates or goes to sleep. I'm a little bit concerned, not so much about the HGST drives (not any important data on them), but about my 4TB HDD, because I feel that it should be turning off, when in reality it never actually turns off. (This data all came from CrystalDiskInfo). So, I have 2 questions: 1. Is this a normal thing that happens, and 2. Should I be concerned about this high POH count (and if it is not normal, is there a way to fix it, and if so, how)? And how long should I expect these drives to last? I know that the HGST drives have an MTBF of about 1 million hours, but does this correspond to how long they will actually work for? Thanks in advance!

~Doombot1

 

[Solandri]

For most electronics and mechanical devices with rotating parts like HDDs, it's the start/stop cycles which put more wear and tear on them, not how long they've been powered on. Every time you power down and power back up, the temperature change causes expansion and contraction, putting stress on the materials and components. The sudden surge of electricity into the circuits can cause high transient voltages which may cause weak circuits to pop. For mechanical systems like HDDs, it gives lubricants a chance to drip down and away from the places they're supposed to be lubricating.

Unless power consumption is a concern or (for HDDs) there's a noise issue, I generally leave my electronics on all the time. I've experienced about a half dozen cases where I was called in to maintain a system which had been powered on for months or years, and it failed shortly after a reboot (usually due to the HDD failing to spin up or starting an awful grinding noise).