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[fordem]

Interesting comment - a couple of points...

1 - The majority of disk wear occurs at start-up and spin-down - when the platters are not rotating, the heads are actually in contact with them, and it takes a couple of revolutions for the platter to build up enough "lift" to get the heads airborne - I figured you knew this - based on your previous post.

2 - Spool up/spool down also causes repeated heating/cooling cycles which is also not good for the disks - better you run them at a constant temperature.

The only reason I know of for hibernation is energy saving - on a consumer NAS which is probably not in use for more than a few hours a day (when do you use your's - I'd guess in the evenings when you get home from work), you can save quite a few bucks over a year.

[conq]

Frodem,   I mentioned the wear issue with spin up in my pervious post.  The simple fact is a disk is less likely to fail if it's OFF. This is true with all electronics since heat is the enemy. I've seen many a disk fail from just being a hot standby. While this is an interesting discussion let's get back to the problem at hand instead of deflecting.

[hilaireg]

conq,

Heat is only a problem in a poorly ventilated environment where the DNS-323 metal casing - which is intended to serve as a 'heat sink' - cannot disperse the heat from the HDD's.

If you notice, the DNS-323 draws air from a vent located on the front bottom of the panel and exhausts via the rear.   If you're not convinced, wet your finger and place it near the bottom front.  As long as the front air intake is not blocked and there is sufficient space around the outside of the DNS, there should be no issue with leaving them on 24x7x365.

The average lifespan of a consumer HDD is approximately 3-5 years - which is typically based on approximately 60%-70% read/write activity.  Most HDD manufacturers provide this data in the detailed specifications.  The lifespan of HDD's are typically reduced in the following conditions:

- spindle spin up/down
- stepper motor lift/park (spool up/down)
- insufficient ventilation
- sudden power loss
- expansion/contraction (heatup/cooldown)
- controller board failure
- high RPM (10K+)
- poor quality control (or 'lemon')


Nowadays, HDD manufacturers create two distinct classes of HDD's; 1) low usage and 2) high usage.  For example, Seagate HDD with NAS in the model number are intended to run at high I/O capacity 24x7x365 and are typically used in RAID-based environment.

Most professionals and businesses design their RAID solutions with a Hot-Spare and a Cold-Spare.  This ensures that when an HDD RAID member fails, the RAID controller immediately 'fails-over' to the Hot-Spare.  Most IT professionals typically configure their RAID devices:

- to set a 'Failed' indicator on the failed member
- to send an alert to a monitoring system so as to notify someone that the RAID device requires attention
- to have someone replace the failed HDD with the Cold-Spare and purchase a new Cold-Spare in preparation for the next failure.


Lastly - to save costs - most home users select 'Low Usage Class' HDD's in low-end NAS solutions ... including myself.  As a rule, I always purchase an extra HDD which I keep handy in preparation for the time when one of the HDD's fail.

In short, 'fordem' is not deflecting but pointing out that disk wear is subject to environmental factors and usage.  As a professional, I replace an HDD a month in my home equipment ... as a result of the excessive I/O that I place on my HDD's.

Best,