If we take the supported PCIe 2.0 speed, that's 5GT/s, i.e. equivalent to 5Gbit/s for the x1 interface. It's not enough to saturate even a single SATA 6Gbit/s link, but current HDDs are not going to exceed roughly 250MBytes/s and will be much slower than that for random workloads (i.e. can only reach that as a peak transfer rate or when streaming contiguous blocks). Even when the individual drives are limited by the PCIe bandwidth, it should still easily saturate the 1Gbit/s Ethernet under the right workloads. Copying between two drives might just about saturate a 2.0 x1 link if the copying is performed as large contiguous transfers.I'd be interested in that too. With five drives on a single PCIe lane performance is going to be interesting. If all the drives are active you'll be lucky if you can saturate the ethernet connection. And copying data between two drives is going to be half that speed.
For completeness, PCIe 3.0 is 8GT/s, if the link is being overdriven. In practical terms, that's nearly enough to saturate 4 typical (e.g. IronWolf) HDDs via a x1 link. I'm also ignoring the cache on the drives themselves, which can obviously briefly saturate a SATA link, just looking at the rate of transfer to/from the magnetic media, as that will usually dominate performance considerations.
Statistics: Posted by Murph9000 — Sat Jan 11, 2025 12:40 am