NVME aborting outstanding i/o and controller resets

Patrick M. Hausen hausen at punkt.de
Fri Apr 12 19:22:28 UTC 2019

Hi Warner,

thanks for taking the time again …

> OK. This means that whatever I/O workload we've done has caused the NVME card to stop responding for 30s, so we reset it.

I figured as much ;-)

> So it's an intel card.

Yes - I already added this info several times. 6 of them, 2.5“ NVME „disk drives“.

> OK. That suggests Intel has a problem with their firmware.

I came across this one:

Is it more probable that Intel has got buggy firmware here than that
„we“ are missing interrupts?

The mainboard is the Supermicro H11SSW-NT. Two NVME drive bays share
a connector on the mainboard:

	NVMe Ports ( NVMe 0~7, 10, 11, 14, 15)

	The H11SSW-iN/NT has tweleve (12) NVMe ports (2 ports per 1 Slim SAS connector) on the motherboard.
	These ports provide high-speed, low-latency PCI-E 3.0 x4 connections directly from the CPU to NVMe Solid
	State (SSD) drives. This greatly increases SSD data- throughput performance and significantly reduces PCI-E
	latency by simplifying driver/software requirements resulting from direct PCI-E interface from the CPU to the NVMe SSD drives.

Is this purely mechanical or do two drives share PCI-E resources? Which would explain
why the problems always come in pairs (nvme6 and nvme7, for example).

This afternoon I set up a system with 4 drives and I was not able to reproduce the problem.
(We just got 3 more machines which happened to have 4 drives each and no M.2 directly
on the mainboard).
I will change the config to 6 drives like with the two FreeNAS systems in our data center.

> [… nda(4) ...]
> I doubt that would have any effect. They both throw as much I/O onto the card as possible in the default config.

I found out - yes, just the same.

> There's been some minor improvements in -current here. Any chance you could experimentally try that with this test? You won't get as many I/O abort errors (since we don't print those), and we have a few more workarounds for the reset path (though honestly, it's still kinda stinky).

HEAD or RELENG_12, too?

Kind regards,
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