Date: Tue, 14 May 2019 08:59:01 -0700 From: George Hartzell <hartzell@alerce.com> To: Matthew Seaman <matthew@FreeBSD.org> Cc: freebsd-questions@freebsd.org Subject: Re: Suggestions for working with unstable nvme dev names in AWS Message-ID: <23770.58821.826610.399467@alice.local> In-Reply-To: <08660a2a-489f-8172-22ee-47aeba315986@FreeBSD.org> References: <23770.10599.687213.86492@alice.local> <08660a2a-489f-8172-22ee-47aeba315986@FreeBSD.org>
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Matthew Seaman writes: > On 14/05/2019 03:35, George Hartzell wrote: > > Can anyone speak to the current state of device names for nvme disks > > on AWS using the FreeBSD 12 AMI's? Is name-stability an issue? If > > so, is there a work-around? > > I don't know about device name stability in AWS instances, but if you > are using ZFS, then shuffling the disks around should not make any > difference. With physical hardware it should be possible to eg. pop the > disks out of one chassis and insert them into another in whatever order, > and the system will still boot correctly. This sounds like the virtual > equivalent of that. > [...] Thanks for the response! Yes, once I have them set up (ZFS or labeled), it doesn't matter what device names they end up having. For now I just do the setup by hand, poking around a bit. Same trick in the Linux world, you end up referring to them by their UUID or .... The tricky bit is the automated setup. Say I ask for two additional devices, "this" and "that". I intend to use "this" for high performance what-cha-macallit so I specify high IOPS and etc.... I intend to use "that" for less important stuff, so I specify "lower" performance. Now as the machine's provisioning itself (e.g. Ansible), how can I reliably decide which to `zpool create` or `glabel` or ... with which names? The Linux world worked around this with the `udev` rules and *etc* that I described earlier. There are hacky ways to work around it, I could ensure that they're different sizes and use that to decide. I could do it in two stages. *etc...* I'm just wondering if there's a way to leverage the bit of info AWS has tucked away for us. g.
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