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Date:      Tue, 6 May 2025 13:31:23 -0400
From:      Charles Sprickman <spork@bway.net>
To:        Colin Percival <cperciva@tarsnap.com>
Cc:        freebsd-stable@freebsd.org
Subject:   Re: NVMe (U.2) hot-swap support status?
Message-ID:  <5530E3D8-B2F8-4101-91B1-D8BAC17D2FDA@bway.net>
In-Reply-To: <01000196a3fb8737-9e591147-f4fd-439d-85bc-5f155be4bebb-000000@email.amazonses.com>
References:  <2E8A7BC6-6C3F-431F-B6F0-2611577B8028@bway.net> <01000196a3fb8737-9e591147-f4fd-439d-85bc-5f155be4bebb-000000@email.amazonses.com>

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> On May 6, 2025, at 1:04=E2=80=AFAM, Colin Percival =
<cperciva@tarsnap.com> wrote:
>=20
> On 5/5/25 21:54, Charles Sprickman wrote:
>> Anyhow, we're trying purchase a few servers (likely this Supermicro: =
https://www.supermicro.com/en/products/system/UP/1U/SYS-111E-WR) and =
since manufacturers don't seem to validate for FreeBSD these days, I was =
hoping for some community input.
>> Last time I looked into this NVMe (specifically the "U.2" format for =
servers that includes hot swap) was supported in FreeBSD but hot swap =
was kind of iffy. I don't think too many FreeBSD users/developers at =
that time had the hardware, most people seemed to just be using an =
on-board NVMe drive on desktop or laptop systems, and there's not any =
real call for hot swap in that segment.
>> I have a thread on the forums linked below, but really what I'm =
looking to find is some larger orgs that are running NVMe drives and can =
confirm hot swap works as expected, if there's any gotchas to be on the =
lookout for, etc. Trying not to overcomplicate it, but we don't want to =
be stuck with a bunch of servers that might be less stable than our =
current SAS/SATA servers. We exclusively use ZFS, if that's useful info.
>=20
> I can't speak to *physical* hotplug, but I've put a lot of energy over =
the
> past few months into making sure that nvme "hotplug" is 100% =
functional in
> Amazon EC2.  If you run into problems it's probably going to be due to
> broken firmware,
[...]

Can you explain a bit here if you've got a few minutes?=20

I'm used to the old world concept of IDE/SCSI/SAS controllers (esp. RAID =
controllers) where you've got a lot of processing going on in the card =
to go from the drive interface to whatever kind of bus the controller =
sits on in the PC. But in the case of NVMe, what even is a "controller"? =
Is it not just a card that's combining/arbitrating PCI-e lanes from a =
bunch of drives to the PCI-e bus? Where would be the firmware and what =
would be the compatibility issues? I admit I don't use any NVMe stuff =
anywhere, so I'm not very familiar with it, and especially not with this =
setup where we have a "controller" involved...

Thanks,

Charles

[...]
> so unless anyone has experience with that specific server
> I think the best answer you can get is "it should work but you need to =
test
> it and find out".
>=20
> --=20
> Colin Percival
> FreeBSD Release Engineering Lead & EC2 platform maintainer
> Founder, Tarsnap | www.tarsnap.com | Online backups for the truly =
paranoid
>=20
>=20




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