An exercise on binomial coefficient identities

Recently, I received an email asking how I got the closed form of a summation in one of my publications. I checked my archive and did not find the calculation back then. Here I do it again, so I will have it.

Resolving ix4-300d being stuck at 0% of RAID reconstruction with 4 drives

Lenovo ix4-300d is a cost-effective 4-bay network attached storage (NAS) for home use. It does not support hot swapping, but offers otherwise most commonly used NAS features. I have 4 3TB Western Digital Red drives running a RAID-5 array with it now, but when I first put the drives in, I did come across some gotchas.