storage Difference between SSD via Sata, M.2 SSD and SSD via PCIE

[Gurky]

Afternoon all so this is probably going to be me doing some babbling to try and get my question out in a way that can be answered.

 

Just to start I know (and I hope most people do) that in terms of speed HDD is the slowest followed by SSHD (Hybrid drive) then fastest being SSD.

So what exactly are all these other types of a believe SSD. Such as M.2 which i think plugs directly in to the motherboard and also PCIE drives such as I think Intel Optane drives.

 

I'll attach a few photos so maybe that can help.

 

Thank you in advance

Gurky 

 

[Dujith]

M2 is an interface and not a SSD type. SSD type would be TLC, MLC ect.

They can be connected by SATA, M2 or PCIE (and some others, but those are rare). The interfaces will dictate the maximum speed you can get.

 

So depending on which interface you will want to use you pick a SSD with that interface. Only the very high end SSD's will need M2/PCIE for their transferspeed.

 

[mariushm]

m.2 is a connector that has the wires required for pci-e , sata and usb

 

a sata ssd or a m.2 ssd that uses the sata interface to transfer data would be limited to 6 gbps (~580 MB/s maximum)

 

a m.2 ssd which uses the pci-e side of the m.2 connector would be limited in speed to what the memory chips on it are capable of, then what the controller on the ssd is capable of and last by the number of pci-e lanes active in the m.2 connector and the pci-e version used.

 

The maximum number of pci-e lanes in the m.2 connector is 4, so you have the equivalent of a pci-e x4 slot in the m.2 connector.

This means you have a maximum theoretical speed of 4 x 970 MB/s if it's pci-e v3.0 , or 4 x 500 MB/s if it's pci-e v2.0

 

For example, if you connect your m.2 ssd to a m.2 connector that's connected directly to your Ryzen or Threadripper cpu, those pci-e lanes come from the processor so they're pci-e v3.0 , which means you'll get up to 4 GB/s

If the motherboard has two m.2 connectors, then if the second m.2 connector even has the pci-e side active, it's 99% guaranteed to be pci-e lanes coming from the chipset. At least n the case of B350 and x370 chipsets, these two chipsets only create pci-e v2.0 lanes, so the second m.2 connector would use up to 4 x pci-e v2.0 lanes, leaving you with a maximum of 4 x 500 MB/s = 2 GB/s

 

In some motherboards, the BIOS will let you restrict the m.2 connector to use just one lane or - i think it's possible but not sure - just two lanes, instead of 4.

For example, let's say a chipset only creates 10 pci-e lanes and the motherboard manufacturer uses one for onboard audio, one for onboard network and so on, leaving with only 5 pci-e lanes left.

The motherboard maker could add a pci-e x4 slot and a m.2 connector on the motherboard and then give you the option :  use m.2 connector at maximum speed (4 lanes)  but disable the pci-e x4 slot or limit it to x1 speed, or restrict the m.2 connector to one lane or only sata and leave the x4 slot at maximum number of lanes (for example let's say user wants to install a 10gbps network card, where having 4 lanes would matter)

[Jurrunio]

SATA SSD: limited by the 600MB/s bandwidth of the SATA standards. nowhere near as fast as PCIe ones

 

M.2 SSD: Two types, SATA and PCIe. M.2 is just the connector or form factor, it's M.2 versus 2.5", not M.2 versus SATA. SATA ones are slow as 2.5" SATA ones, PCIe ones are fast as PCIe x2 or x4 SSDs directly on PCIe slots.

 

PCIe SSDs directly on PCIe slots: with PCIe connector rather than M.2 because many servers do not have M.2 connectors. In other words, they are meant for professional users and RICH enthusiasts, not general consumers.

 

NVMe: it's a technical standard for the storage drive controllers used by PCIe based storage. Its analog is AHCI, on SATA based storage. People refer M.2 PCIe SSDs as NVMe SSDs for clarification, but it's technically wrong.