Question Medium-sized NVMe array setup suggestions?

_Rick_

Diamond Member
Apr 20, 2012
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I'm taking the next step with my storage setup, and will in the near future buy 8 M.2 SSDs - DRAM-less 2TB drives, ideally MLC, but potentially even QLC. Trying to get the best deal, and I can wait a while.

My intended use case is in my home NAS, to host home directories across my other machines - and potentially be able to free up the SSDs installed there mostly for steam libraries. I do expect the steam client to not enjoy having to share the directory, so we will see about that.
Also will likely host some game servers, own-cloud-style services and such - hoping to run either single node k8s or just plain docker/compose, and avoiding VMs.
Got 16 Zen4c and 128 GB of RAM on the machine, but no plans to run 100-concurrent-users-databases on the array - instead it will mostly be media. Worst case will be stuff like Windows AppData.
OS is Gentoo, I've neen running btrfs without major issue for a while (although i got annoyed with it refusing to mount when degraded, unless you specify it, which broke booting off of a single disk.
I heard good, bad and ugly about ZFS - since I am not chasing IOPS significantly, I doubt it will matter.
Will have a local spinning rust backup, so if the worst happens, I should be able to recover most of it. Bonus points, if I can get snapshots of the volumes.

Main considerations:
Don't eat my data please - and allow me something like RAID5/6 so I don't need to throw half the capacity away for RAID 1/10.
Don't eat the SSDs: write amplification of SSDs should not be multiplied significantly. It's bad enough as it is, on these cheap drives.
Make drive swaps easy: The disks will be mounted in an externally accessible bay, and I am looking into NVMe somewhat-hot swapping them, if they break - if the setup then makes me faff around with more than two lines of shell, I'll be annoyed.
Don't get slower than HDDs - regardless of what I am doing. I know that SSDs will already degrade horrendously once you eat through their cache - I need a storage setup where that condition remains the worst case.
Support TRIM - which probably throws out classic SW-RAID, as it gets much harder to track which blocks are used, if the FS needs to pass the information through.

My current default would be BTRFS with "RAID 1", so that all files are replicated exactly once, without any kind of parity overhead - and maybe I'll create a throw-away volume without replication, for scratch data, if needed.
If you have any additional input, on read-heavy "low-cost" NVMe arrays (the disks only cost as much as it costs to get them wired and installed...)

Why am I doing it? It's pretty cool, and I had too many HDDs die on me lately. And disk spin-ups need to go back into the 2000s :D
 

sdifox

No Lifer
Sep 30, 2005
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Umm how are you going to hook up 16 nvme? If you are sharing pcie through bifurcation, you may as well go with SATA SSD. Media content doesn't need high throughout.
 

_Rick_

Diamond Member
Apr 20, 2012
3,956
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Umm how are you going to hook up 16 nvme? If you are sharing pcie through bifurcation, you may as well go with SATA SSD. Media content doesn't need high throughout.
I built a machine around that:
Lot's of PCIe is fairly easy to get, once you're off the gimped gamer platforms, I'm looking at PCIe v4 SSDs mostly,
both for power/heat reasons with that enclosure, and to have a chance in hell, to get them wired up.
Going to bifurcate one 16x PCIe and two 8i MCIOs into 8 4-lane connections.
Should still be 10x faster than SATA, and SATA SSDs actually aren't that much cheaper these days.
 

Shmee

Memory & Storage, Graphics Cards Mod Elite Member
Super Moderator
Sep 13, 2008
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Have you considered buying pulled u.2/u.3 enterprise SSDs? Or do they have to be m.2?
 

sdifox

No Lifer
Sep 30, 2005
99,462
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I built a machine around that:
Lot's of PCIe is fairly easy to get, once you're off the gimped gamer platforms, I'm looking at PCIe v4 SSDs mostly,
both for power/heat reasons with that enclosure, and to have a chance in hell, to get them wired up.
Going to bifurcate one 16x PCIe and two 8i MCIOs into 8 4-lane connections.
Should still be 10x faster than SATA, and SATA SSDs actually aren't that much cheaper these days.
wait, you said 8 nvme totally 16tb, not 16 nvme right?

Get two of these and call it a day

I don't think hotswap nvme is a good idea to start with.
 

_Rick_

Diamond Member
Apr 20, 2012
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It's definitely not a good idea, but proper external access to my storage devices has become a priority for me as of late.
Taking down the machine, and trying to figure out which device (by missing serial number in sdparm) is the one that I have to pick out got old pretty fast after the third or fourth time, and is not going to get much better with a card-style mounting options.

It would still leave most of the questions I actually have around getting a neat storage setup out of it just as unclear as before.

Since hotplug mostly works for u.2 and u.3, I do think that with should be able to eventually expect success - and if after 14 days of messing around I cannot get a stable setup, I may just send the whole thing back to the retailers, and opt for U.2 after all - maybe grab some used ones with some PBs of write endurance left on them.

M.2 as a consumer standard leaves me with much better options in the future to low-cost expand, and availability of deals with warranty is a sure thing. The same cannot be said for used U.2 - so currently I prefer M.2 for that reason.