Flash emonSD in Hard disk USB HDD, Possible?!

Daoudi_imad · 2018-09-12T09:09:34.952Z

Hi
How can i flash EmonSD in Hard disk USB?
I flash it with Etcher but when i connect the hard disk USB with my raspberry, i got this messages :

sda attached SCSI DISK
crng init done
It still blocked.
Thank you for your help.

danbates · 2018-09-12T14:38:33.008Z

Might be worth asking here: https://forums.resin.io/c/etcher

Bill.Thomson · 2018-09-12T18:29:05.046Z

This should get you started:

Moving the emonSD Linux partitions to a USB HDD emonSD

Various users have described moving the SD card root operating system image to an external HDD to better protect the SD card from corruption when subjected to uncontrolled power downs. Indeed, the requirement to maximise SD card life has spawned a great deal of effort on the part of the developers to create a low-write SD card image. This topic is intended to discuss the issues relating to moving away from the SD card to external USB HDDs, which are considered more robust to power failures

Bill.Thomson · 2018-09-12T18:38:24.238Z

danbates:

Might be worth asking here: https://forums.resin.io/c/etcher

From the Etcher forum:

Flashing disk images to partitions isn’t supported by Etcher at this time, and given that disk images are full-disk images, and contain their own partition tables, bootloader code etc. this would involve quite a bit of manual fiddeling to pull off, and might even be rather hard if the filesystem in the image isn’t resizable or isn’t implemented by your host OS.

So unless he wants to use the entire HDD, it won’t work.

If perchance he does want to use the entire HDD, all he has to do after putting the image on it
is edit his config.txt file and /etc/fstab file to tell his RPi where to find the root partition.

borpin · 2018-09-13T06:59:46.897Z

Here are 3 different tutorials on this. To my mind, the third is the most interesting but only available on a Pi 3 ~~(and is a oneway operation - cannot be undone).~~ (see below).

https://www.raspberrypi.org/documentation/configuration/external-storage.md

https://www.maketecheasier.com/boot-up-raspberry-pi-3-external-hard-disk/

https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/msd.md

Daoudi_imad · 2018-09-13T12:03:08.007Z

Thank you for your response, But according to the tests I have done, I find that these methods work only with rasbian versions and not with Emoncms (debian) !!!
it’s normal?!

borpin · 2018-09-13T12:39:27.857Z

The EmonSD card is based on Raspbian Lite (Jessie rather than Stretch for the moment). If you are using the RFM card that may make a difference.

I have an installation of EmonCMS running on a Pi B+ with the system on a USB HDD but I used a process that moved it from an SD card. It is possible but not a standard setup.

You could start with a clean Raspbian Lite image and follow the build guide to self install EmonCMS.

Bill.Thomson · 2018-09-13T15:03:59.050Z

borpin:

(and is a oneway operation - cannot be undone).

To avoid any possible confusion…

Indeed it is a one-way operation. But, an RPi so modified can still boot from an SD card.

(in case anyone gets the idea that a Pi modified in that manner can no longer boot from an SD card)

borpin · 2018-09-13T15:21:44.698Z

Bill.Thomson:

borpin:

(and is a oneway operation - cannot be undone)

Indeed it is a one-way operation. But, an RPi so modified can still boot from an SD card.

There is a line in this link that states

“… This will set a bit in the OTP (One Time Programmable) memory in the Raspberry Pi SoC that will enable booting from a USB mass storage device. Once this bit has been set, the SD card is no longer required. Note that any change you make to the OTP is permanent and cannot be undone.” (my emphasis).

@Bill.Thomson - Does this statement mean that although the SD card is no longer required an SD card can still be used to boot from instead of an USB mass storage device? I took it as the former but the ambiguity in the above does exist. If so, I wonder why the warning? Would it mean that if an USB mass storage device was plugged in it will only boot from the USB mass storage device whether there is an SD card in there or not?

Bill.Thomson · 2018-09-13T15:26:34.183Z

borpin:

Does this statement mean that although the SD card is no longer required an SD card can still be used to boot from instead of an USB mass storage device?

Correct. It can boot from either media. I modified one of my Pi 3s, and it can boot from SD card or
a USB thumb drive, hard disk, etc. I’ve got USB to Compact flash adapters that I’ve put 1-inch microdrives in, and they work like a champ.

borpin · 2018-09-13T15:28:40.463Z

Bill.Thomson:

Correct. It can boot from either media.

Interesting, thanks. What if both are plugged in, does it have a priority of boot locations?

Bill.Thomson · 2018-09-13T15:30:40.812Z

The modification makes the Pi wait for several seconds (I forget the exact number) before trying the
USB boot. (to ensure the SD card slot is empty) So if both are inserted, the Pi will boot from the SD card.