Concept for high density JBOF units to be used in AI datacenters and by hyperscalers.
Publishing date: 10/06/2026
Last updated: 20/06/2026
Small disclaimer: I don't know if this is possible yet. I'm not an engineer in his field, if any engineer reads this he/she can explain why this would or wouldn't work in the "Discussions" tab.
This concept is designed to help AI datacenters and Hyperscalers with their growing needs of storage but also efficiency in both power and reducing water consumption.
- Core:
The concept is built over the existing Seagate Exos EX4U74 and Exos DC4U100, two 4U JBOD-SAS units that have respectively 74 and 100 hotswap bays for SAS HDDs.
- Power, storage, design:
Since enterprise SSDs like the Solidigm D5-P5336 can reach the capacity of 122.88TB in both U.2 15mm and E1.L 9.5mm it could make for previously unseen levels of storage density, but we'll get back to this later on.
Enterprise SSDs are also more power efficient than HDDs: HDDs idle at around 5W and peak at roughly 10-15W under load, while enterprise SSDs still idle at 5W and peak at 24W (Solidigm specs, SSDs usually idle slightly lower than HDDs). Despite the fact that HDDs draw less power when under load, the speeds are limited by the RPMs and the data is both written and accessed slower when compared to SSDs. Additionally HDDs need more power to spin up when turning on, wearing on the internal motors, and have an higher chance of failing (from 1.5-2% annual failure rate) due to their moving parts. The heat, and vibrations, generated by HDDs are also a problem since the failure rates jump up 30% for every 5°C above 40°C. SSDs, on the other hand, can be liquid cooled to reduce the heat output, are quieter since they don't rely on mechanical parts and have a higher speed output: something needed when accessing AI data sets and is generally nice to have.
As I previously mentioned the storage capacity of a singular D5-P5336 can reach 122.88TB, and since it's slimmer than an enterprise HDD, more can be fitted in a 4U chassis. So let's say that we can fit 110-115 SSDs in one chassis and we get a raw storage capacity of 13.2-13.8PB. And with the possibility of using specifically designed water blocks a whole rack can be liquid cooled through a CDU for maximum capacity, or through an internal loop sacrificing capacity. This concept can be also used for other formats such as E3.S 7.5mm for higher read/write speeds and even more slots, maybe 120-125 slots.
For formats such as E1.L 9.5mm, E1.S 9.5mm and E1.S 15mm there is the possibility of putting them in 1U chassis and fitting them with an opposed central midplane, with the possibility of 24 slots per row and either two or three rows depending on various factors like engineering and cooling requirements. Alternatively there is the option to have the SSDs parallel to the front of the chassis and have either a left or right sideplane with a realistic capacity of 11 maybe 12 slots. This option is aimed to be more serviceable than its counterpart, aimed for maximum storage density instead.
So in total for the midplane design with dual row design, 48 slots (2 rows of 24 slots), a singular 1U rack can reach a density of roughly 5.76PB per rack with the option to be either liquid cooled through external CDU or air cooled. The sideplan design with 11-12 slots can have 1.3-1.47PB of density, with the added benefit of easy serviceability.
For all the air cooled variants of these designs I'd suggest fans in a push-pull configuration: one set of fans stays at the front of the units while the other set sits at the very back of the unit.
- Back I/O connectivity:
For connectivity I was thinking 4-6 QSFP-DD ports, able to support anywhere from 100GbE to 800GbE by simply swapping out the transceiver, making serviceability easy and fast in the event of a port failing.
Sketch of the 1U sideplane design, made with diagrams.net (draw.io). Temporary measure as I'm trying to make a proper model.
Links:
- Seagate Exos EX4U74: https://www.seagate.com/it/it/products/data-storage-systems/scale/ex4u74/?store=1
- Seagate Exos DC4U100: https://www.seagate.com/it/it/products/data-storage-systems/scale/dc4u100/?store=1
- Solidigm: https://www.solidigm.com/
- D5-P5336 U.2 15mm: https://www.solidigm.com/products/data-center/d5/p5336.html#form=U.2%2015mm&cap=122.88TB
- D5-P5336 E1.L 9.5mm: https://www.solidigm.com/products/data-center/d5/p5336.html#form=E1.L%209.5mm&cap=122.88TB for the other form factors used in the concept consult the "products" section
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