What are the essential care to maintain a Hard Drive healthy and consequently to preserve the Data? From care, tips, best brands/models of hardwares and best softwares to often test the HD health.

- Backup (Unfortunately the most of the people, only think about it when it happens some problem);
- Best Power Supply?; (Cost-benefit ratio)
- Best UPS?; (Cost-benefit ratio)
- Best Hard Drive brands/models?; (Cost-benefit ratio)
- Enable S.M.A.R.T. feature in the BIOS for all Hard Drives connected to the Computer and
- Scans the Hard Drive for Bad Blocks/Bad Sectors and different types of errors using: HDD Tune Pro, CrystalDiskInfo and GSmartControl.

How often it is good to scan errors on the Hard Drive?

TL:DR - just see adminzen.org especially http://adminzen.org/adminzen.png

Healthy hard drive doesn't guarantee data preservation; verified backups do.

If data are important to you:
Have a backup plan. Follow that plan religiously.
Daily, Weekly, Monthly, Offsite etc
Test that you can actually recover using the backups.

(seen a university come unstuck backing up to the same tape for years. No one understood that magnetic media had a lifespan of a few months. Tried to recover from tape that was almost transparent there was such a level of degradation).

---

that aside

Power:
Keeping a system up and running, always start with good supply of electricity and work through that chain up to and including the PSU in the PC.

Suitable AC mains /(if critical, a Backup generator too) -> substantial capacity UPS -> quality PSU specced to include any possible upgrades and additions.

One of the main pitfalls i see is domestic customers buying the "best bang for the buck" machine and then adding components with no thought to the power required for stable operation.
Machines often get here, clogged with carpet fluff and dust (overheating) with additional multiple small drives added as they ran out of space, extra DVD trays to cope with ripping, card readers, sound cards, extra USB hubs and allsorts of whatnot. It's like expecting the pet hamsters wheel to hook up the entire house.
http://i.imgur.com/RkJEtVc.jpg

Original "off the shelf" machine will be specced with the cheapest available PSU, and ancillary gear, that meets the required retail price point.

Drive Quality:
Domestic/Consumer grade drives aren't built with stability or reliability foremost in mind.
They are built to provide, as reliably as possible, storage within the confines of what the current price point is.
Treat them as disposable or buy enterprise quality gear.
Enterprise quality still requires a backup plan.

As usual, and with most things you are ok as long as you don't breach Wheaton's Law.

_________________
Когда хочется кушать – съешь всё.
Голод не тётка!