Comment by geerlingguy | Hacker News Reader

Comment by geerlingguy | Hacker News Reader

There are a few people currently working on NAS boards based on the CM4. A few different approaches in terms of chipsets used and performance targets.

I'm trying to track them in this GitHub issue [1] but a couple people have remained more or less anonymous as they don't want to attract attention too early.

The single PCIe lane is the biggest limitation if you're looking for raw speed (350 MB/sec is kind of the upper real-world sustained transfer limit), though since the gigabit Ethernet port is on a different interface, you can still expect to get 80-100 MB/sec network transfer speeds.

Something like this, with the right case and OMV or other adequate software would be a relatively competitive replacement for low-end NASes.

I'm also exploring building a 2.5G NAS with a CM4, but the PCIe bus speed limitation is what kinda hamstrings that. Hopefully the next Pi revision has a 4x (at least) lane, like the RockPro64.

[1] https://github.com/geerlingguy/raspberry-pi-pcie-devices/iss...

"There are a few people currently working on NAS boards based on the CM4."

I continue to appreciate the time and attention you are paying to these new boards on your blog and in your comments here at HN - thank you.

I am having trouble sourcing maxed out CM4 parts - that is, 8 GB ram and 32 GB onboard storage[1]. They are either sold out until August or October or something silly like that or they are only available in 200+ quantity.

Do you have any suggestions as to where I could source those ?

[1] CM4008032, I think ...

80MB/sec is actually quite fine for most NAS applications.

Anyone trying to get 10G speeds out of a high end NAS won’t be looking to Raspberry Pi solutions right now, anyway.

The real advantage, IMO, is that this helps kick off the popularity of DIY NAS solutions based on ARM hardware. It’s not the first solution in this space, but Raspberry Pi is great for taking things mainstream.

I imagine that a few years from now we’ll have an even faster Raspberry Pi to build a NAS around. These current-gen solutions might be just what we need to get the software sorted out before the powerful hardware arrives.

Its sorta hard to justify those at the moment, since the XHCI interface on the base Pi4B is more than capable of maximizing the PCIe x1 interface. Basically, you can run a NAS at the capabilities of the machine with random USB3 JBODs.

So a $100 5+ bay USB3 JBOD, RPi4B run over the 1G nic, and a 64-bit arm64 distro (because rasbian will die with modern SATA disks in a larger capacity JBOD) and you have a fairly reasonable low end NAS for basically the price of the disks.

(or just plug in 4 of USB3 easystores/etc and save on the enclosure).

I’ve done this (JBOD with USB 3.0 drives on a Pi 4) and it’s surprisingly effective.

I can easily saturate the 1G NIC which is more than sufficient for my use case.

I don’t use RAID or ZFS so neither the CPU or RAM are limiting factors.

Have you come across anyone producing a PoE board for the CM4 - just looking for a network port, USB and perhaps SD card (similar to a Ubquiti Cloud Key)?

(the Gumstix camera board is overkill for my needs)

Why not use the regular Raspberry Pi 4 with the PoE module?

The CM4 is only useful in most cases if you want to use the PCIe bus for something else, or if you’re trying to embed it in another product.

The existing PoE module is noisy as hell, and due to it's design it's a PITA to fit a different fan

CM4 on a PoE baseboard offers far more cooling options

Waveshare has one. Haven't used it personally but it seems to suit your needs. Though at ~$50 you're probably better off just getting a Pi 4B + PoE hat.

https://www.waveshare.com/compute-module-4-poe-board.htm

Can POE provide enough power to turn SATA drives? I kind of figured for a NAS it probably makes sense to go with a regular power supply, especially since it’ll be mounted in an easy to access location for drive replacement.

802.3at specifies max 30W at the output port at 600mA so in theory you could shunt that to 5V and get about 5A after losses. Enough to spin up a 3.5" SATA.

But most consumer retail PoE switches are only .3af compliant which give 15W minus transmission losses.

802.3bt can provide higher power, easily enough to run a few HDDs but there are few switches on the market that offer 802.3bt. Almost nothing available for the residential/consumer space.

A regular Raspberry Pi with a cheap POE USB-C splitter from Aliexpress works very well.

https://a.aliexpress.com/_mMpvxGV

"Have you come across anyone producing a PoE board for the CM4 ..."

Wait, I thought the official CM4 breakout/dev board (the one with the PCIe slot on it) had PoE, right ?

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