[Raspberry Pi] I Thought /var/log Was Safe on a Ramdisk, but Docker Logs Were Being Written to the SD Card

Tue, 23 Mar 2021 00:01:29 +0900

To extend the life of the SD card, I configured /var/log to live on a Ramdisk. But Docker logs are output to /var/lib/docker/containers, so of course that did nothing for Docker logs.

Test Environment

Raspberry Pi 4 (8GB RAM)
Ubuntu 20.10 64-bit

$ cat /etc/fstab
LABEL=writable / ext4 defaults 0 0
LABEL=system-boot /boot/firmware vfat defaults 0 1
tmpfs /tmp tmpfs defaults,size=128m 0 0
tmpfs /var/tmp tmpfs defaults,size=128m 0 0
tmpfs /var/log tmpfs defaults,size=64m 0 0

What I Changed

Change Docker's logging driver settings. Check the official site for details.
Reference: Configure logging drivers

[Raspberry Pi] apt Started Failing After I Put tmp on a Ramdisk

Sun, 03 May 2020 12:03:34 +0900

I configured a Ramdisk to extend the life of the SD card.
After that, when I upgraded the kernel with apt, an error occurred because /var/tmp did not have enough capacity.

I did not record the error message, but I think it was No space left on device.
I handled it by setting larger sizes for /var/tmp and similar directories.

$ cat /etc/fstab
LABEL=writable / ext4 defaults 0 0
LABEL=system-boot /boot/firmware vfat defaults 0 1
tmpfs /tmp tmpfs defaults,size=128m 0 0
tmpfs /var/tmp tmpfs defaults,size=128m 0 0
tmpfs /var/log tmpfs defaults,size=64m 0 0

The site I used as a reference for extending the SD card life set /var/tmp to 16MB, and anyone who copied that as-is will probably run into the same thing.

Ramdisk on No Subject - nosubject.io -

[Raspberry Pi] I Thought /var/log Was Safe on a Ramdisk, but Docker Logs Were Being Written to the SD Card

Test Environment

What I Changed

[Raspberry Pi] apt Started Failing After I Put tmp on a Ramdisk