Comment by pjdesno

I work with storage, and "how long does it take" questions come up a lot - filling an HDD, wearing out an SSD, etc.

A day is about 10^5 seconds. 10^6 seconds is about a fortnight. A year is about 10^4 hours, or 310^7 seconds, so a billion seconds is about 30 years.

Typically the numbers you're multiplying are vague enough that these numbers are more than accurate enough - e.g. if you want to support 20MB/s for a year, back of the envelope says 600TB, exact says 630.72. You typically picked "20" out of thin air, and unless you have a very* specific use case (e.g. fixed-rate video streams) it's probably only accurate +/- 50% at best.