Does interface bandwidth and/or interface type (SATA/NVME) affect IO and Random 4KB RW performance

James Hopwood

12/16/23, 8:13 PM

TLDR: The advertised IOPS of NVME drives is leaps above any SATA SSDs, but how much of this is due to limitations of the:

Interface (SATA/NVME)
Interface Bandwidth (PCIE Gen 4, Gen 3, SATA 3, SATA 2)
Or Memory Controller Quality?

Premise: I've got an old - old Dell PowerEdge T410 server I've brought some upgrades for, 64GB of DDR3 1333Mhz RAM, and 2x Intel X5675 6/12 Xeons. But ultimately the main bottleneck in putting some extra life into this thing comes down to the storage... With only:

SATA 2 ports
PCIE Gen 2
No NVME ports

There's only so snappy I can make the old-timer. Currently, with a few somewhat old, low-capacity, desktop SATA SSDs (240GB WD Green, and 2* 128GB SanDisk Plus) it does surprisingly well over SATA 2, but hardly bares comparison to my desktop's Samsung 980 Pro (512GB, PCI-E Gen 3 NVME). I don't really care about sequential performance, it's nice to have but doesn't really have a real-world impact when used for the OS or VMs which is the main thing I'm looking for here, and from what I'm aware, this primarily comes down to IOPS and Random 4KB RW performance.

I know that SATA SSDs are all but legacy these days and any good memory controller is going straight into an NVME SSD, and that's why I'm considering getting a single PCI-E Gen3x4 NVME M.2 adapter and running at Gen 2 bandwidth with a modern NVME SSD like the 970 Evo Plus. That's still a theoretical maximum of 2GBps, plenty for the rare sequential workload.

What I really care about is the IOPS and Random 4KB RW performance. Would such a legacy system meaningfully reduce the "real-world" performance of a modern NVME SSD in such a configuration and if so, how much?

And when it comes to SATA 2 vs SATA 3, is it a similar story? Would these older SATA 3 SSDs see an improvement in IOPS and/or Random 4KB RWs when upgraded to a SATA 3 interface?

How much of the non-sequential performance improvements of SATA SSDs to NVME SSDs come down to the quality of the memory controllers rather than the AHCI vs PCI-E interfaces?

I really couldn't find anything online about this specific aspect of modern storage performance on slower interfaces so technical explanations would be appreciated.

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storage

sata

pci-express

nvme

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