Pi boot from SSD or HDD

Hi all.

Has anyone managed to get their Pi to boot directly from USB attached SSD or HDD with (importantly) two (or more) devices attached?

I still use an SD card for the /boot partition to differentiate between USB attached devices.

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Chris Elvidge, England

I don't have an answer for you, but this sounds interesting, can you please explain why you want this feature, what's the advantage?

TIA, NoReply

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Am 18.01.2019 um 14:54 schrieb NoReply:

Probably the aim for a defined boot sequence in case of multiple (bootable?) SSDs/HDDs ?

- Udo

120GB SSD for System and Music (boot on SD card); I do a lot of temporary files. 5TB HDD for media (TV/Radio downloads, TV/Radio recording) files, with a 50GB partition for backup.

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Chris Elvidge, England

Thats a smaller backup partition that I'd expect. What are you backing up: just /home, and how many backup copies?

You do realise, of course, that a permanently online backup scheme like that is fairly unsafe because lots of scenarios can kill it along with the rest of the system. A better plot would be to backup over an ethernet connection to removable storage on a separate system, keeping the backup offline when not actually being accessed, and preferably having at least tow generations of backup devices.

I've just bought a pair of 1TB WD Essentials USB drives. Yes, I know, I should have bought them separately so they come from separate production batches. So far they're looking good - quite a bit faster than the 320GB

2.5" WD Blue drives they replace and that will be too small fairly soon. I make offline weekly backups of four systems (3 x 64 bit Fedora, 1 x RPi model B) using rsync to put all four backups on the same disk. Both backup disks are in a fire safe when not being used, so there is always one backup copy in the fire safe.

Paranoid? You bet, when backups are involved.

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I do, but didn't think it was relevant to the question "NoReply" asked.

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Chris Elvidge, England

out of curiosity, what OS is on your /boot SD card?

(please don't say windows, please don't say windows...)

Assuming Linux, you could simply use the 2nd hard drive as a mount point and access it like part of the normal file system, whenever it's present. You don't need to boot FROM it in order to use it. Just set things up so whenever you hotplug it, the thing mounts to the correct place, and all of your applications know where that is.

If you want to go against "what THEY say are the defaults" you might have to shut off auto-mounting, and then write a daemon to look for the drive being attached. when it's attached, using the gpt ID to match against your list, then issue a 'mount' command. pretty simple, 5 second polling would probably do it.

But if it's being auto-mounted you'd have to shut that off, yeah. I shut off auto-mount anyway. I can type the 'sudo mount' command myself...

and if you put an entry into /etc/fstab you can just specify the mount point, like 'mount /media/my-mount-point' or whatever. A few caveats, but basically make sure the device name matches whenever you plug something into a USB port. Typically it will. Or, you can just 'mount /dev/whatever /media/my-mount-point' with your daemon script. Simple.

Then whenever you plug the removable media in, it will mount. You could also force a dismount with a separate script. Your first script would have to recognize that it mounted the device, and not try to re-mount it after you unmount it. A little tricky, not too hard. Just wait until it's unplugged before trying to re-mount.

Anyway, it'd be a fun little test project, wouldn't it?

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I just use LABELs to make sure thing are mounted (automatically) where I want them (except on mmcblk0p1). Then bind mount to various other directories. Also sshfs mount to "other" computers.

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Chris Elvidge, England