While NVMe flash storage has gone mainstream in the enterprise, form factors and connectivity best suited to larger-scale use cases have lagged a little.
Now, however, the Enterprise and Data Centre Standard Form Factor (EDSFF) for NVMe flash drives is well along the on-ramp to datacentre adoption.
Here we look at EDSFF, some basics of its spec, the variants it comes in, who supplies the drives, and the storage array products EDSFF is available in.
EDSFF was developed by 15 companies as a form factor for flash drives that use the NVMe protocol, the solid state successor to the SCSI-based disk input/output methods that were designed for spinning disk. NVMe is now pretty much ubiquitous in shared flash storage, and offers access speeds tens or hundreds of times quicker than possible with SCSI protocols.
Meanwhile, EDSFF drives make use of PCIe gen 4 or gen 5 specification connectivity. Gen 4 delivered double the transfer rate of the previous generation, which meant around 128GBps. Gen 5 doubles that again to a theoretical 256GBps. That’s potentially more than 100TB per hour from one drive.
EDSFF was preceded as an NVMe flash connect by U.2 and M.2. Just as a recap, U.2 is a 2.5” – “traditional”, i.e. dating back to spinning disk – drive format and can be NVMe, but also the SCSI-based SAS or SATA.
Meanwhile, M.2 comes in a range of form factors – but basically a “gumstick” – aimed at internal laptop, PC and server mounting with a physical footprint of up to 22mm x 110mm.
There are numerous EDSFF form factors. One that gets noticed is the ruler-style E1.L – short for EDSFF 1U Long – which as its designation suggests, is made so that up to 32 can be slotted into a 1U array. The “ruler” bit comes from the fact it’s about a foot long (325mm) and something like the width of a steel rule (38.6mm). They can be arranged 12.5mm apart and such density – with 36 media chips on the E1.L – sees capacity of 1PB in 1U claimed. It is hot-pluggable and front access serviceable.
Then there is E1.S – S being short for short – at just over 110mm long and slated as a successor to the use of M.2 form factor drives, which are popular in hyperscale datacentres. They’re about the same length as M.2 drives – so a good fit in servers – but pack in more media laterally and come in a range of widths with varying amounts of media and cooling capability.
Finally, EDSFF E3 family drives – in short and long variants – are aimed as successors to U.2 2.5” format drives in servers and storage subsystems.
Intel, Kioxia and Samsung
EDSFF drives are available from Intel, Kioxia and Samsung, with PCIe 4.0 and 5.0 connectivity available and TLC and QLC media on board.
Intel’s E1.L can provide up to 30.72TB per drive, and uses QLC flash. Intel claims 2x to 3x thermal efficiency improvements over U.2 drives.
Kioxia seems keener to highlight E1.S and E3 drives, with a range of specs available. At the time of writing, Kioxia and Samsung seem to be leaving the E1.L field to Intel for now.
EDSFF in storage and server hardware: Not much yet
Those putting EDSFF drives into hardware systems include:
Supermicro, with 1U storage servers based on E1.L and tellingly named the Petascale E1.L server, plus an E1.S-based member of its SuperStorage portfolio.
Dell EMC allows for EDSFF drives in its XE2420 Edge Server, while IBM mentions using EDSFF drives, among other NVMe formats, in its Power System servers.
EDSFF hasn’t made an appearance in any arrays from the big six yet, leaving SuperMicro’s storage server clear in the field so far. This will undoubtedly change.