The lowest density chips are still going to be way smaller than even a E1.S board. The only thing you might be able to be cheaper as you’d maybe need fewer SSD controllers, but a 3.5" would have to be, at best, a stack of SSD boards, probably 3, plugged into some interposer board. Allowing for the interposer, maybe you could come up with maybe 120 square centimeter boards, and E1.L drives are about 120 square centimeters anyway. So if you are obsessed with most NAND chips per unit volume, then E1.L form factor is alreay going to be in theory as capable as a hypothetical 3.5" SSD. If you don’t like the overly long E1.L, then in theory E3.L would be more reasonably short with 85% of the board surface area. Of course, all that said I’ve almost never seen anyone go for anything except E1.S, which is more like M.2 sized.
So 3.5" would be more expensive, slower (unless you did a new design), and thermally challenged.
The market for customers that want to buy new disks but do not want to buy new storage/servers with EDSFF is not a particularly attractive market to target.
Chips that can’t fit on a 76mm board do not exist in any market. There’s been some fringe chasing of waferscale for compute, but it’s a nightmare of cost and yield with zero applicable benefits for storage. You can fit more chips on a bigger board with fewer controllers, but a 3.5" form factor wouldn’t have any more usable board surface area than an E1.L design, and not much more than an E3.L. There’s enough height in the thickest 3.5" to combine 3 boards, but that middle board at least would be absolutely starved for airflow, unless you changed specifications around expected airflow for 3.5" devices and made it ventilated.
Given that there are already 32TB 2.5” SSDs, what does a 3.5” buy you that you couldn’t get with an adapter?
A better price as low density chips are cheaper.
And you can fit in more of those in a bigger space = Cheaper.
The lowest density chips are still going to be way smaller than even a E1.S board. The only thing you might be able to be cheaper as you’d maybe need fewer SSD controllers, but a 3.5" would have to be, at best, a stack of SSD boards, probably 3, plugged into some interposer board. Allowing for the interposer, maybe you could come up with maybe 120 square centimeter boards, and E1.L drives are about 120 square centimeters anyway. So if you are obsessed with most NAND chips per unit volume, then E1.L form factor is alreay going to be in theory as capable as a hypothetical 3.5" SSD. If you don’t like the overly long E1.L, then in theory E3.L would be more reasonably short with 85% of the board surface area. Of course, all that said I’ve almost never seen anyone go for anything except E1.S, which is more like M.2 sized.
So 3.5" would be more expensive, slower (unless you did a new design), and thermally challenged.
Native slotting into server drive cages. No concerns about alignment with the front or back.
The market for customers that want to buy new disks but do not want to buy new storage/servers with EDSFF is not a particularly attractive market to target.
What kind of server? Dell’s caddies have adapters, and I’m pretty sure some have screw holes on the bottom so you don’t need an adapter.
They should be cheaper since theres a bunch more space to work with. You don’t have to make the storage chips as small.
Chips that can’t fit on a 76mm board do not exist in any market. There’s been some fringe chasing of waferscale for compute, but it’s a nightmare of cost and yield with zero applicable benefits for storage. You can fit more chips on a bigger board with fewer controllers, but a 3.5" form factor wouldn’t have any more usable board surface area than an E1.L design, and not much more than an E3.L. There’s enough height in the thickest 3.5" to combine 3 boards, but that middle board at least would be absolutely starved for airflow, unless you changed specifications around expected airflow for 3.5" devices and made it ventilated.
A big heat sink like they used to put on WD Raptor drives.
Build quality