[SAC] New parts order osgeo3/4, quick question

[Alex M]

A quick check before I put the order in.

The replacement PSU are straight forward:
2x $35 = $70 +Tax
https://www.amazon.com/dp/B00456W6A2/ref=cm_sw_r_tw_dp_U_x_voaaDbABVTDES

The new hard drives are a little more complicated.
How much capacity do we actually need? OSGeo7 has a capacity of
4x8TB=32TB before redundancy. With 6 slots on osgeo4 the closest match
would be 6x6TB=36TB for ~$1290 +Tax

Seems like a lot to spend on such and old machine (2010), and I wonder
if we should consider osgeo3 + osgeo4 ~ osgeo7 capacity
6x2TB=12 TB $709.86
OR
6x4TB=24 TB $1019.94

Drive options
https://www.amazon.com/dp/B07D98C9XB/ref=cm_sw_r_tw_dp_U_x_KYaaDbHS3TGFS

Opinions?

I suppose even though the hardware is old, the drives could be moved to
another system later if we wanted. Plan to order in 24 hours.

Thanks,
Alex