And that nicely wraps up the case for consumer HA-/HM-SMR drives. Thanks, but no thanks.
I was just coming to ask that question after seeing the 16Tb Ironwolf pro drives are on sale at a pretty nice price in the UK, so thank you 
On a related have there been any public road map releases about these new drives? I imagine IX need to be on top of that; if the major producers are forcing any new tech which clashes with ZFS it will have to be designed around and I only see that taking timeâŚ
Personally I see a couple of these drives in my future as a very size efficient back up system for replicationâŚ
Yeah the Mozaic drives are a different kettle of fish. They apparently appear as two independent drives to the OS so a whole new world of issues arrives with deciding how to use them.
Iâve recently gone to market and 24TB was as good as it gets atm for conventional CMR drives.
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Are the Mozaic drives multi-actuator like the Exos 2X series? It doesnât carry the same MACH.2 branding, so it might just be increased areal density.
Itâs important to disambiguate between MA meaning âMicrowave-Assistedâ vs MA meaning âMulti-Actuatorâ - which I believe is part of the reason they went to HAMR (Heat-Assisted) as the abbreviation of choice there.
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Ah perhaps Iâm confusing the two then apologies.
Itâs seems that 24TB was as big as I could get just recently so perhaps theyâre not available to purchase in bulk just yet or the price is just 
Agreed that if weâre only talking a difference of 2TB then best keep away from SMR at least for now.
I thought shingling was supposed to yield a 20% delta at best. To OEMs, thatâs huge as it allows the potential deletion of a platter while costing virtually nothing. Hence WD doing its users dirty by surreptitiously shipping SMR drives while festooned with the traditional red NAS line sticker.
Does it have fewer spindles; is it dramatically cheaper?
I donât disagree with the conclusion, but I agree thatâs curious.
Exactly.
âŚwhere can you buy one?
Unless your name is Google, Amazon, Facebook or Microsoft, I donât think you canâŚyet
Iâd just be happy with better priced 20 TiB drives
Price per TB (edwardbetts.com)
Itâs getting better, but still $10/TiB is a sweet spot that we havenât seen yet.
But 4TiB SSDs have come down really far in price these days, which may be even more enticing, but weâre still like 1/8 the size for 4x the cost.
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HmmâŚ
Theoretically you can get close to 100%, if all space is shingled. That of course is not practical because it implies needing to re-write an entire platter if you need to start at the wrong side. That is why they would use guard tracks between shingled groups to reduce the amount of re-write.
But, only 20%? I guess if it eliminates a platter, (and associated head, with electronics), it could be enough of a savings to be worth it to a vendor.
I am NOT however condoning what Western Digital did to their NAS Red line. That is unforgivable and unforgettable! But, I find it quite amusing that WDâs Web site page for NAS Reds is STILL broken after week;
https://www.westerndigital.com/products/internal-drives/wd-red-sata-hdd?sku=WD40EFAX
Hereâs hoping the WD Reds die a miserable death!
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The Wikipedia entry for SMR claims about 25% but like you said, it will depend on how many guard tracks you put down between sectors to retain at least some real world performance.
Reading that, I also found out that hardware-wise CMR vs. SMR are actually different because the write head is bigger for SMR than CMR.
But clearly SMR must be cheaper on a $/TB basis than CMR or WD wouldnât have pulled the Red switcheroo stunt with its users.