[conspire] Taxonomy of SSD sticks for M.2 sockets

[Rick Moen]

----- Forwarded message from Rick Moen <rick at linuxmafia.com> -----

Date: Tue, 25 May 2021 13:53:31 -0700
From: Rick Moen <rick at linuxmafia.com>
To: golugtech at diypython.us
Subject: [Golugtech] 500 GB WDC M.2 2280 _NVMe_ is $64.99 (was: 500 GB
	Western Digital M2-2280 is $54.99)
Organization: If you lived here, you'd be $HOME already.

Quoting Alex Finkel (alex.finkel at gmail.com):

> I agree and for not much more money ($70), you can get the an NVMe
> drive with the same capacity: 
> https://www.newegg.com/western-digital-black-sn750-nvme-500gb/p/N82E16820250109

I note from the picture that this stick has an M.2 edge-connector with
subtype M keying, hence will require a motherboard that has a subtype-M
socket, rather than a subtype-E one.  (Again, check compatibility before
buying.)

This particularly unit shares with the earlier WDC unit reliance on 
cheaper, denser-packed, shorter-service-life 3D TLC NAND storage.
On the plus side, unlike the SATA-type stick's 3-year warranty, this one
has a 5-year warranty.

I note the product page's caution that it may be desirable, depending on
application (but mostly for desktop machines), to use the variant with
attached _heatsink_, costing a bit more.  Intuition suggests that if
you're not sure, and it's not destined for a well-ventilated server,
shell out $20 more for the version with heatsink.

As a point of clarification:  Upthread I spoke of the difference between
SATA-interface SSDs on M.2 and PCIe-interface SSDs on M.2 (making the 
point that the latter is much preferable).  My understanding is that
NVMe is an advanced _data-transfer_ protocol for PCIe-physical-interface
devices.  So, NVMe data addressing _implies_ the PCIe physical bus.

NVMe was concocted in 2011 to replace the very successful but aging 
AHCI data-addressing protocol that emerged with early SATA -- revamped
to take advantage of PCIe electrical signaling.  More at:
https://www.partitionwizard.com/partitionmanager/pcie-nvme.html

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