Jimmy Wilkinson Knife wrote:
Everybody seems to be getting excited about the nvme interface SSDs on
M2 connectors. And everybody says they're so much faster than SATA 3
which is limited to 6Gbps. But it isn't. SATA 3.2 came out years ago
and it's 16Gb/s. So is there any point in buying an M2 shaped SSD? I
can't find any sensible comparisons online anywhere.


I can give you a simple metric for comparison.

NVMe uses four lanes.

SATA uses one lane (for the regular flavor).

All of these technologies borrow ideas from
one another. As the rates go skyward, the ideas
transfer from one standard to another.

But it's the lane count that decides which one
ultimately has the highest rate. For example,
PCIe Rev.4 is coming out soon, which could, potentially,
make an NVMe double in speed.

There's a Samsung NVMe that does around 2.5GB/sec.
And the reason it stops there, is PCI Express has
a buffer dependency, and the chipset doesn't use
big enough buffers. The wiring supports ~4GB/sec,
the buffers, not so much.

What even comes close, as a competitor ? AFAIK, NVMe
is winning right now.

If a storage tech comes along that used 8 lanes
to connect to the motherboard, then it will be the
next winner.

*******

How fast does my software go ?

1) Naively written program written by home user: 300MB/sec
2) HxD hex editor, when searching for a string: 600MB/sec
2) 7ZIP CRC32 right-click checker: 1500MB/sec

What this means is, there's really no consumer that I know
of, that uses the 2500MB/sec the Samsung gives.

Regular SATA covers "regular" programs, the ones that
aren't particularly optimized for any purpose.

So while the fanbois love their NVMe and "let me RAID0 that for you",
there aren't a lot of other bits in the computer that put the
speed to good usage.

Even an Areca RAID controller, probably delivers around 2GB/sec.
So RAIDing hard drives isn't the answer. Connecting only
four SATA III SSDs would saturate the engine.

And anything faster than that, is probably too expensive to own :-)

There's all sorts of tech out there... that has absolutely
no presence on the web at all. Black technology belonging
to three letter government agencies. I got a view of such
a piece of gear at a storage conference (it wasn't particularly
classified, and was more of a stage prop kind of thing), and
even if I don't know what's current, I know they have better
stuff than we do :-)

Perhaps doing some research on CERN and their Internet 2 storage
schemes, would give some idea what more bleeding edge stuff
looks like.

Summary: Do the lane count, decide who is the (eventual) winner

Paul