If you're gonna build for redundancy, avoid WD Red. They use SMR platters and it doesn't play nice with RAID configs. You'd have to get a WD red plus or red pro to get a CMR drive which actually works in a RAID array. You don't have to worry about accidentally getting an SMR drive with ironwolf though since that whole section is Seagate's branding only uses CMR.
If you're gonna build for redundancy, avoid WD Red. They use SMR platters and it doesn't play nice with RAID configs. You'd have to get a WD red plus or red pro to get a CMR drive which actually works in a RAID array. You don't have to worry about accidentally getting an SMR drive with ironwolf though since that whole section is Seagate's branding only uses CMR.