Linux-Fan wrote:> From my experience, RAID1 on USB does not work reliably. > See https://lists.debian.org/debian-user/2014/09/msg00602.html > > For NAS-style use cases, I consider single board computers to have an > advantage mainly in terms of power consumption. In case one is going to > run two (or even more?) rotating disks in conjunction with such a board, > from my point of view, power consumption raises significantly making the > use of an energy efficient "regular" system a viable alternative to > consider. So the conclusion is to take the SATA extention/expansion board. I saw some of them (4 ports) are coming with external power supply. IMO it doesn't matter what "regular" system you take, cause the disk has the same power consumption be it on the "regular" or on the rpi.
I said "regular" so unspecifically, because for most people, RPI / ARM SBC style computers are not "regular". From my experience, it is more difficult to install Debian on them and even then less software is comptabile -- mostly if you need proprietary stuff, but this can include self-written¹...
Consider my "regular" system: An amd64 PC with a "regular" tower-style case: It has a single ATX PSU (only one power connector needed, attaches problemlessly to any UPS) and offers space for at least two 3.5" internal HDD drives -- all neatly organized, single PSU solution.
Consider a Raspberry PI: External PSU for the Raspberry PI, two external PSU for two external HDDs. It gets easier with the SATA hat, but even then you need to somehow power the whole system. A single PSU at the USB input for the RPI is likely not to be sufficient etc. Much more thinking about electricity and the case to embody all those components. And then you have not solved the software side yet.
Also, never underestimate the OS disk: RPIs boot off a microSD card. I am surprised that my Banana Pi M2+EDU still runs on its first card after more than two years, so it seems to be possible to get some reliability out of the cards. Still, if thinking about a RAID1 of HDDs, to comploete the reliability consideration, one would possibly like to boot the OS off a RAID1 as well; impossible with RPI AFAICT...
I don't understand how power consumption can raise significantly because of the board? Do you mean that processing the data demands more power on the CPU?
Processing data on ARM may even be more efficient than on amd64. I meant the relation between the board's operating power and the disks'. If you calculate 4W for each disk and 4W for the board you already spend two times the power on disks than on the board. I know that there are amd64 systems available with ~15W idle power consumption. Add two disks: ~23W -- still maybe twice as much as for an equivalent RPI system, but much easier to setup and from my personal point of view it is more the kind of technolgoy to which I am used (i.e. simplified maintenance).
Look here exactly for the purpose: https://shop.allnetchina.cn/products/dual-sata-hat-open-frame-for-raspberry-pi-4
They seem to recommend using an ATX PSU for 3.5" HDDs, so it is getting more similar to a "regular" PC and finding a case for all this is getting more difficult? :)
¹) Yes, I was already bitten by this; details available for interested parties
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