Log2Ram

Log2Ram works just like ramlog for systemd (on Debian 8 Jessie for example).

Useful for RaspberryPi for not writing on the SD card all the time. You need it because your SD card doesn’t want to suffer anymore!

Explanations: The script creates a /var/log mount point in RAM. So any writing of the log to the /var/log folder will not actually be written to disk (in this case to the SD card on a Raspberry Pi) but directly to RAM. By default, every day the CRON will synchronize the contents in RAM with the folder located on the physical disk. The script will also make this copy of RAM to disk in case of machine shutdowns (but, of course, it still won’t do it in case of power failures). This way you can avoid excessive writing on the SD card and extend its life.

Log2Ram‘s script works on every Linux system. If you don’t have Systemd, you can still use Log2Ram with your own daemon manager.

Log2Ram is based on transient /var/log for Systemd. For more information, check here.

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Table of Contents

1. Installation
2. Is it working?
3. Upgrading
4. Customization
5. Troubleshooting
6. Uninstallation

Installation

Via APT (recommended)

echo "deb [signed-by=/usr/share/keyrings/azlux-archive-keyring.gpg] http://packages.azlux.fr/debian/ bookworm main" | sudo tee /etc/apt/sources.list.d/azlux.list
sudo wget -O /usr/share/keyrings/azlux-archive-keyring.gpg  https://azlux.fr/repo.gpg
sudo apt update
sudo apt install log2ram

Manually

curl -L https://github.com/azlux/log2ram/archive/master.tar.gz | tar zxf -
cd log2ram-master
chmod +x install.sh && sudo ./install.sh
cd ..
rm -r log2ram-master

For better performances, RSYNC is a recommended package.

REBOOT before installing anything else (for example apache2)

Is it working?

After installing and rebooting, use systemctl to check if Log2Ram started successfully:

systemctl status log2ram

This will show a color-coded status (green: active/red: failed), as well as the last few log lines. To show the full log (scrolled to the end), run:

journalctl -u log2ram -e

The log is also written to /var/log/log2ram.log.

You can also inspect the mount folder in RAM with:

df -hT | grep log2ram | awk '{print " Name: " $1 "\nMount: " $7 "\n Type: " $2 "\nUsage: " $6 "\n Size: " $3 "\n Used: " $4 "\n Free: " $5}'

Returns:

 Name: log2ram
Mount: /var/log
 Type: tmpfs
Usage: 72%
 Size: 128M
 Used: 93M
 Free: 36M

Or also:

mount | grep log2ram | awk -F'[ ()]+' '{print "   Name: " $1 "\n  Mount: " $3 "\n   Type: " $5 "\nOptions: " $6}'

Returns:

   Name: log2ram
  Mount: /var/log
   Type: tmpfs
Options: rw,nosuid,nodev,noexec,noatime,size=131072k,mode=755,uid=100000,gid=100000,inode64

If you do not get any line as response of these commands, something is not working. Refer to this section.

Upgrading

You need to stop Log2Ram (systemctl stop log2ram) and execute the installation process. If you used APT, this will be done automatically.

Customization

Variables

In the file /etc/log2ram.conf, there are nine variables:

• SIZE: defines the size the log folder will reserve into the RAM (default is 128M).
• USE_RSYNC: (commented out by default = true) use cp instead of rsync (if set to false).
• NOTIFICATION: disables the notification system mail if there is not enough place in RAM (if set to false).
• NOTIFICATION_COMMAND: Specify the command for sending error notifications (By default, it uses the mail command).
• PATH_DISK: activate log2ram for other path than default one. Paths should be separated with a ;.
• JOURNALD_AWARE: enable log rotation for journald logs before syncing. (default is true). Check the comment in the config file or the Troubleshooting section below for journald SystemMaxUse recommendations.
• ZL2R: enable zram compatibility (false by default). Check the comment in the config file. See https://github.com/StuartIanNaylor/zram-swap-config to configure a zram space on your raspberry before enabling this option.
• COMP_ALG: choose a compression algorithm from those listed in /proc/crypto. (default is lz4). See Compressor section below for options.
• LOG_DISK_SIZE: specifies the uncompressed zram disk size

Refresh time

By default, Log2Ram writes to disk every day. If you think this is too much, you can run systemctl edit log2ram-daily.timer and for example add:

[Timer]
OnCalendar=
OnCalendar=Mon *-*-* 23:55:00

Note: The OnCalendar= is important because it disables all existing times (e.g. the default one) for log2ram.

... Or even disable it altogether with systemctl disable log2ram-daily.timer, if you instead prefer Log2Ram to be writing logs only on system stops/reboots.

Compressor

Compressor for ZRAM. Useful for the COMP_ALG of ZRAM in the config file.

Compressor name	Ratio	Compression	Decompress.
zstd 1.3.4 -1	2.877	470 MB/s	1380 MB/s
zlib 1.2.11 -1	2.743	110 MB/s	400 MB/s
brotli 1.0.2 -0	2.701	410 MB/s	430 MB/s
quicklz 1.5.0 -1	2.238	550 MB/s	710 MB/s
lzo1x 2.09 -1	2.108	650 MB/s	830 MB/s
lz4 1.8.1	2.101	750 MB/s	3700 MB/s
snappy 1.1.4	2.091	530 MB/s	1800 MB/s
lzf 3.6 -1	2.077	400 MB/s	860 MB/s

Now, muffins for everyone!

Troubleshooting

Existing content in /var/log too large for RAM

One thing that stops Log2Ram from functioning is if /var/log is too large before starting Log2Ram the first time. This can happen if logs had been collected for a long time before installing Log2Ram itself. Find the largest directories in /var/log (this example command only shows the 3 largest):

sudo du -hs /var/log/* | sort -h | tail -n 3

If the /var/log/journal is very large, then there are a lot of system logs. Deletion of old “archived” logs can be fixed by adjusting a setting. Edit the /etc/systemd/journald.conf file and add the following option:

SystemMaxUse=20M

Or the more radical version of directly flushing the journal to a size that matches log2ram size imediately (Be aware that this flish flush the systemd journal logs imediately to the given size!)

journalctl --vacuum-size=32M

This should be set to a value smaller than the size of the RAM volume; for example, half of it could be fine. Then, apply the new setting:

sudo systemctl restart systemd-journald

This should shrink the size of “archived” logs to be below the newly imposed limit. Reboot and check that Log2Ram now works properly:

sudo reboot

Wait until system reboots...

systemctl status log2ram

Uninstallation :(

(Because sometimes we need it)

Via APT

sudo apt remove log2ram

You can add the --purge argument to remove Log2Ram config files as well.

Manually

chmod +x /usr/local/bin/uninstall-log2ram.sh && sudo /usr/local/bin/uninstall-log2ram.sh