7200 vs 5400

[Raevyn]

Hello

So I have the chance to buy some 10TB drives, WD Reds, for a decent price but they are 5400 speed. I am curious if that is something that would make any read difference in my build. I would be using 5 drives in raidz3 and using SSD for L2ARc and SLOG. The other option is from what I can tell, I can make a pool and grow the size by replacing drives of larger sizes without having to make an entirely new pool, so I could just buy smaller drives to start.

 

[Apollo]

If you are using raidz3 with only 5 drives, this means you are not looking much for space but toward more reliability.
I think your setup goes backward as L2ARC and SLOG will most likely not benefit you in any way.
You have to consider redundancy, IOPs.
If you have enough RAM and depending on the type of data being accesses, having enough RAM could leverage your concern.
Depending on your workload and snapshot schedule, you may find 5400 RPM is more than enough or you could end up with an under performiung setup if you have many connected users requesting non ARC stored data.

 

[BR14]

I think 5400 rpm reds are much better priced than 7200. Consider extra heat and noise that comes with 7200 - you do not describe the case they go in. Also, WD 8TB ( and bigger) externals contain what most agree to be re-labeled 5400 reds at much better prices.