> Another issue is performance : you'll get 4x more IOPS with 4 x 2TB drives 
> than with one single 8TB.
> So if you have a performance target your money might be better spent on 
> smaller drives

Regardless of the discussion if it is smart to have very large spinners:
Be aware that some of the bigger drives use SMR technology.
Quoting wikipedia on SMR:
"shingled recording writes new tracks that overlap part of the previously 
written magnetic track, leaving the previous track thinner and allowing for 
higher track density.”
and
"The overlapping-tracks architecture may slow down the writing process since 
writing to one track overwrites adjacent tracks, and requires them to be 
rewritten as well."

Usually these these disks are marketed "for archival use".
Generally speaking you really should not use these unless you exactly know 
which write workload is hitting the disk and it is just very big sequential 
writes.

Cheers,
Robert van Leeuwen
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