booting freebsd on raspberry pi from external USB drive

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OK, I'll answer my own query. I finally hit on the right set of buzz-words for the search engine, and found the answer at

The usb disk is slow enough to need extra boot delay before / is mounted. So I've put into loader.conf kern.cam.boot_delay="10000"

and all is well.

(Footnote: the loader.conf files /must/ be root-owned, or they are silently ignored during boot. Took ages to find that somehow loader.conf was owned by my non-root persona. Wierd. But all's well now.)

This thread piqued my interest enough to search for an answer. As you imply, it takes too much sleuthing to discern the proper keywords to obtain meaningful results.

Beings you've already done the heavy lifting, is it possible for you to share the /etc/fstab syntax to auto mount a usb file system? TIA.

Thank you,

WEIRD.

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Thank you. I have a habit of getting that one wrong. Most wierd :-}

Nothing special; from the PI:

/dev/da0p2 / ufs rw,noatime 1 1

But I think the noatime can go - I believe it's to save additional wear on an SD card.

It breaks not only the 'i before e', but also the 'except if it sounds like the sea'

So does rein. and reign.

and a few other excamples.

Yes, but performance will be better with it too, unless the drive is an SSD.

if you were to perform a thorough check of the dictionary you would find that there are actually more words that break the rule than follow it this is one of the reasons why it is no longer taught is schools.

I before E except after C, or when it says "A" as in "neighbour" and "weigh".

(Plus a few weird exceptions which may seize your attention.)

If I'm not mistaken, that gives you the kernel from the microSD card but userland from the USB storage device. That may not be a bad thing depending on what you're doing. If the machine is intended to build its own world and kernel I think it'll make mischief.

I'd be pleased to learn this is untrue.

I elected to use the microSD for / but put /usr /var swap and /tmp on usb partitions on the notion that / is seldom written to.

bob prohaska

Thanks for the comment.

TBH I don't know. I've always found the info for loader confusing; and with ubldr it's not exactly got clearer. Possibly just me - but I'm trying to use the OS, not learn about how it ticks.

My understanding, which is more than likely flawed, is that loader reads the fstab file, and mounts / accordingly, and I think the kernel is then loaded from /boot/.... which would mean (in this case) off the external drive.

But in my case, they're identical anyway, and it makes not one jot of difference in practice for my application.

But it would be good to know for sure!

(I'm not entirely convinced that running 'make buildworld' or whatever on the rpi would be a Good Idea in any event. :-} )

As I've noted elsewhere, the problem I had was due to a race condition for recognising the USB drive and mounting / off it. Suggests to me something not quite kosher in the design of the boot procedure.

This depends on one's definition of "good" 8-) For a minimal power and hardware setup it works fairly well. A complete build/install cycle can be finished in a day.

Hopefully somebody will chime in with an accurate answer. I wanted to do the very same thing a couple of years ago and reluctantly concluded it was impossible. It would be good to learn that something has changed, but I've come across nothing to suggest it.

In point of fact, I've spent the last two years trying to wear out a microSD card and USB flash filesystem and there's no hint (sound of knuckles rapping forehead) of a problem. If you hook up a serial console and play around with the u-boot prompts you'll find a "boot usb" command.

By no longer care, but maybe you do. The name certainly holds promise.

bob prohaska

On Fri, 14 Jul 2017 23:12:21 +0000 (UTC), bob prohaska declaimed the following:

Run multiple variations of the HINT benchmark setting up a swap file on the SD card...

That will shorten the SD card life significantly!

I don't doubt that flash can be worn out. I simply wanted to see if it's a problem in my application. Seemingly not yet.

How it fails may be more significant.

bob prohaska

We use Pi's to drive serial and USB smartcard multiplexers, it runs a tiny python server sitting on top of a standard Raspbian wheezy, no additional writes over and above what the OS does by default. The cards are now starting to fail after 4 years of 24/7 uptime.

---druck

What failure modes are you observing? Presumably I have another year or so to get ready 8-) It would be good if I could recognize the symptoms.

bob prohaska