Why is mSATA slower than SSD on T430s and W530

[BobA]

I have a T430s system and a W530 system .. each with a Samsung850 EVO mSATA drive. Using CrystalDiskMark, I'm getting sequential read/write speeds on the mSATA about half the speed of my Samsung SSD 840 Pro. All the sites I go to say they should be comparable in speed. Am I missing something? Is the interface that the mSATA plugs into down-level since it's PCIe 2.0? I didn't think the PCIe mattered - that it was a straight through to the SATA channel - or whatever. My ignorance on the hardware is showing, I'm sure ..
Any ideas? Is this normal? Will a later version system behave better?
Thanks ..

[Python.p]

I think the main reason is there in T430s is thinking for WWAN. Same in T420 and X220, slower than E520.

[Cigarguy]

AFAIK Lenovo's 20 and 30 series (i.e. T420, X220, W530, T430, etc) is SATA II speed on mSata. So you should be benching 250-280 MB/s in ATTO. For me SATA II speed is plenty fast enough and is unnoticeable between SATA II vs III during normal everyday usage.

[BobA]

AFAIK Lenovo's 20 and 30 series (i.e. T420, X220, W530, T430, etc) is SATA II speed on mSata. So you should be benching 250-280 MB/s in ATTO. For me SATA II speed is plenty fast enough and is unnoticeable between SATA II vs III during normal everyday usage.

Thanks .. That's the answer for what I was looking for. And I appreciate your thoughts on the speed comparison during normal usage.
When did Lenovo up that to SATA III for the mSATA?

[jdrou]

When did Lenovo up that to SATA III for the mSATA?

Pretty sure they didn't; instead they switched to M.2 slots in later systems (e.g. my T440p). Those are either SATA III or, in the latest generation, PCIe/NVMe. Dell continued to use mSATA in some later systems but I think those were still only SATA II. Unfortunately Thinkpads mostly seem to use the 42mm M.2 which has fewer options than the more common 80mm size.

[ajkula66]

When did Lenovo up that to SATA III for the mSATA?

Pretty sure they didn't; instead they switched to M.2 slots in later systems (e.g. my T440p).

Correct. SATA II is all we'll get from an mSATA slot on any ThinkPad.