Direct Attach vs Expander backplane

[spall]

So..  my main server took a hit from a water pipe I didn't know existed. I have no idea what (if anything) lived through the ordeal, but I'm thinking it's a good time to get away from my Norco 4224 anyway.

 

Looking at Supermicro chassis, I see I have a backplane option of direct attached or expander.  I understand that using an expander will divide up available bandwidth amongst the drives, but the crux of my question is this: Does it split that bandwidth when drives are inactive? Since I'm often only using a couple drives at any given moment (aside from parity checks) would I even notice? Or is it always bandwidth/#connected drives no matter what they're doing? This seems especially critical for the cache drives.

 

Thanks

[JorgeB]

14 hours ago, spall said:

Does it split that bandwidth when drives are inactive?

Nope, devices in use simultaneously.

 

[spall]

@JorgeB

Thanks so much!  I just ordered a chassis with the BPN-SAS2-846EL1 expander backplane. I'll give it a whirl. Based on what you said, it sounds like for my normal usage I'm only gonna maybe see perf hit on parity checks/rebuilds.