Samsung hails the rise of ruler SSDs for the data centre

Samsung has introduced its first ‘ruler’ SSD and says the new format opens the door to large increases in server flash capacity.

The Samsung PM9A3 SSD uses the E1.S enlarged gumstick format. In a flash-optimised 1U server reference design, 32 x 7.68TB drives fit in the front bays of a 1U server, to give 245.76TB of capacity.

Jongyoul Lee, Samsung SVP for memory software development team, who presented the drive at the OCP Virtual Global Summit on May 12, said: “Offering the most 1U server-optimised form-factor, the PM9A3 will improve space utilisation, add PCIe Gen4 speeds, enable increased capacity and more. We see it eventually becoming the most sought-after storage solution on the market for tier one and tier two cloud data centre servers, and one of the more cost-effective.”


The PM9A3 has a PCIe gen 4 interface and uses Samsung’s sixth generation V-NAND with 100+ layers and TLC (3bits/cell) format. Capacities range from 960GB to 7.68TB.

SNIA E1.S diagram

E1.S – S for ‘short’ – is an SNIA-approved variant of the EDSFF or ruler form factor and measures 111.49mmx31.5mm. The current M.2 gumstick format is 110.0mm long by 30.5mm wide. According to Intel, the E1.S design is said to be three times more thermally efficient than U.2 (2.5-inch) form factor SSDs. It is also hot-pluggable.

The E1.L – L for ‘long’ – form factor measures 318.75mm x 38.4mm wide. The greater surface area cand hold three to four times as many flash chips – potentially 30.7TB per drive and 983TB in a 1U server. Intel says the E1.L is twice as thermally efficient as U.2 drives.

Supermicro U.2, M.2, E1.S and E1.L diagram

Samsung is making the PM9A3 available in E1.S, M.2 and U.2 formats. E1.S and U.2 performance is: 900,000/180,000 random read/write IOPS, up to 6.5GB/sec sequential reads and 3.5GB/sec sequential writes.

It is slower in the M.2 form factor, reflecting the PCIe gen 3 and gen 4 speed difference; 500,000/70,000 random read/write IOPS, up to 3.5GB/sec sequential reads and 1.75GB/sec sequential writes.

E1.S reference design

Samsung is open sourcing an E1.S platform reference design to help data centre managers adopt and deploy the E1.S-based storage system. An Inspur-built reference system is available.

Blocks & Files thinks Intel, Kioxia, Micron, SK hynix and Western Digital will have E1.S designs in their pockets and bring them to market this year and next. The E1.L format will enable a bigger jump in 1U server capacity than E1.S, but adoption may be held back by concerns about the effects of drive failure. A drive crash would put more data at risk, increasing the so-called failure blast radius.