jfabernathy wrote: ↑Sat Aug 10, 2019 6:54 pm
Can you explain more about just using the micro SD card for the boot? In my application I'll use the USB3 ports for 256GB Flash Keys. Once the RP3/4 is booted it's going to run mostly out of RAM since mythtv-backend is all that is running. Where is setting up the SD card to do this documented?
I find that if I want a RP3 to do Kodi, I use 18.3. If it's a FE only I use LibreELEC 9.1.002. Very stable
Jim A
mythbackend is constantly writing to disk, and even more so when recording, mariadb is also doing some disk writing as well and of course the operating system will be doing its thing as well.
Here in UK, roughly 2GB per hour per recording for HD, 0.7GB per hour SD for OTA, satellite can be much higher for HD.
Whilst there are many posts around on how to move rootfs from microSD card to an external drive, a lot of them are old and out of date, and in many cases very manual. I have a helper script (attached, just download it, unzip and make sure it is executable) which does most of it.
EDIT 30 March 2020
The latest version of the script is now available from my github repository at
https://github.com/MikeB2013/pi-utils
You just need to start with a working Pi4 install, copy the helper script over to it (put it in /home/pi/)
If using an external hard disk power down Pi BEFORE connecting to a USB port,
You should be ok connecting a single SSD or several USB flash drives to USB ports whilst Pi is powered, assuming official power supply (for Pi4, 1.2A is available over the 4 USB ports).
Everything is done in a terminal session either locally or via SSH.
I use lsblk command to view partition and mount point information.
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pi@raspberrypi:~ $ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 1 57.3G 0 disk
└─sda1 8:1 1 57.3G 0 part /media/pi/f88f7e1a-e0f2-4348-a185-f89955eeffa7
mmcblk0 179:0 0 14.7G 0 disk
├─mmcblk0p1 179:1 0 256M 0 part /boot
└─mmcblk0p2 179:2 0 14.4G 0 part /
The above shows default for /boot (mmcblk0p1) and / (mmcblk0p2)
If flash drive/Hard disk/SSD shown in MOUNTPOINT, usually sda1 (unless you have more than 1 external drive or the external drive has more partitions) in /media/pi/ it needs to be unmounted before running the helper script (script will abort if it finds mounted disk in /media/pi/).
e.g.
now run the script, WARNING all data on target will be destroyed.
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sudo ./pi-SDtoHD-helper.sh -d /dev/sda
after you reboot
you should see from lsblk
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pi@raspberrypi:~ $ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 1 57.3G 0 disk
└─sda1 8:1 1 57.3G 0 part /
mmcblk0 179:0 0 14.7G 0 disk
├─mmcblk0p1 179:1 0 256M 0 part /boot
└─mmcblk0p2 179:2 0 14.4G 0 part /media/pi/rootfs
MOUNTPOINT / is now on sda1, /boot is still on mmcblk0p1 (the micro SD card)
The old / (mmcblk0p2) has been automounted on /media/pi/rootfs, I just ignore it
Mike