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I am, planning a NAS upgrade. We are currently running dozens of low capacity, cheap drives. We are upgrading to a Synology NAS with far fewer, higher capacity drives. As such, these drives will have a higher cost per TB that our lower capacity drives if bought today.

Based on the BackBlaze drive stats report that just came out, prices per TB have leveled out, so assuming that trend remains the same for the next few years to come, there little risk of buying drives a t price per TB far greater than what it will be in a few years.

So, assuming drive price per TB remains relatively constant, is there a standard rule/guidance/practice for planning capacity for a NAS? In other words, how should I determine if I should buy capacity for 1, 2, 3, 4, or 5 years from now for storage requirement that is growing year over year?

I realize this question could be seen as subjective, however, I am asking for an objective standard rule/guidance, or commonly accepted IT best practice for planning NAS capacity, which hopefully, makes it more of an objective ask.

It has been pointed out that this question may be a duplicate of an existing question on Server Fault, but the only answer that comes close to addressing my question references an "Axiom" that summarizes one should just buy large drives instead of small ones. My concern is around for how many years in the future should one buy drive capacity. Based the the responses so far, it may be that there isn't an IT standard rule/guidance/practice for planning such a thing. If that is the case, then that is my answer.

Thank you.

marked as duplicate by DanBig, Tim Brigham, Gerald Schneider, kubanczyk, Andrew Schulman May 18 '18 at 20:14

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.


Plan for a sliding sequence of buys, phased such that you're replacing existing drives before their MTBF runs out (;-))

At that point, buy sizes chosen for the lowest cust over MTBF years: you'll need to spreadsheet that each time, as prices wander around a lot.

To make this easy, buy cabinets that have more empty space than you need, so you can roll stuff into place, and see if you can figure out how not to have a whole cabinet of disks, all the same age.


The industry says that data growth rate for the next 10 years is 40% / year increase.

EMC Report: https://www.emc.com/leadership/digital-universe/2014iview/executive-summary.htm

Older Gartner study: https://www.computerworld.com/article/2513954/data-center/data-growth-remains-it-s-biggest-challenge--gartner-says.html

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