windows 7 - Powering Off Hard Disks, is a life saver or life depleter?

Hardware description and problem introduction:

I'm a Home user and I use Windows in a Home PC, I have 4 internal hard disks connected and running, 1 hard drive is for the OS, and the other hard drives are 'secondary' (They are single partitions, any RAID).

For life circumstances I need to keep my PC ON every 24 hours of every day of every week of every year (I don't have money to buy expensive things such as NATs), the PC does not sleep and does not hibernate and does not turn off, but like I've said, I'm a home user, please don't threat this question like an intensive working PC of a company.

The hard drive that stores the OS is working every minute all day, the others hard drive aren't but I access to those secondary hard drives like 20 times each day to navigate through their folders.

I would like to be sure that I'm doing things the most safe possible that I can, I would like to keep alive the life of my hard drives the maximum time possible, so taking the information that I've explained above I would like to know if in my circumstances it's better to turn off the power of the secondary hard drive devices to save power or not, in the power management configuration that provides Windows.

I ask this also 'cause I'm confused about opinions, an expert hardware 'mechanic' (I don't know the English word, sorry) said me that turning off the power of drives is not the most safer decission IN ANY CIRCUNSTANCES 'cause it depletes the total life time of the device each time that the device re-initializes, for example when a disk is turned off automatically by Windows and then I open the Explorer to navigate inside the hard drive folders it needs to wait some seconds to turn on the device to list the folders, and he said me that those insignificant seconds at the end depletes/waste away the total life time of the disk, and it's safer to don't turn off the power of the devices NEVER.

The question:

Then, what is better and safer for me? let windows power management turn off devices when they are not working, or keep on the power every time?

If turning off the power of the devices at the end it's a life-time consumer then why Windows puts an unsafe checkable option in the power management?

I'm very worried about the future state of my hard drives by let Windows turned them off/on every day 20 times when I need to read those secondary hard drives, so I'm only searching and I only can accept an answer of a professional hardware expert that could clarify my question.

Answer

This is really an opinion based question, so not sure of its suitability, and the answer is, as always "it depends" - on a lot of things. Some of the key elements include -

1. How often do you access the drive ?
   I know you said 20 times per day, however does the OS also access them directly, and are the 20 times per day spread throughout the day ?




2. What environment is it stored in ?
   If there are extremes in temperature, it may be that running the hard drive constantly provides a more constant environment making the drives less prone to failure.

On the flip side, drives are mechanical devices and eventually wear out. There is no "one correct" answer - save as to ensure you have good backups (and RAID1 helps - not sure if you have RAID one, it sounds like you have more RAID0 or JBOD)

Of-course, laptop drives are aften turned off to save power.

I disagree with your "Mechanic" that turning the drive off and on is a bad idea in any circumstances, although he is probably correct in your particular circumstance - When you turn on a drive there is an inrush of current, and the drive spinning up causes stress on it, so it might be an idea to avoid doing this too frequently.

My inclination would be to keep the drives spun up and to install S.M.A.R.T monitoring tools (as well as doing backups), but there is no silver bullet. If you are very concerned about wear, try putting a fan on the drives - although don't be paranoid about temperature [within reason]. Historically higher temperatures were believed to correlate to failure - but that is no longer as true as it used to be.

I also put to you that consumer drives are designed to be turned on and off - and particularly "green" drives. This article is on point and may be worth a read.