log2ram/README.md

# 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](https://github.com/azlux/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](https://www.debian-administration.org/article/661/A_transient_/var/log).

_____
## Table of Contents
1. [Installation](#installation)
2. [Is it working?](#is-it-working)
3. [Upgrading](#upgrading)
4. [Customization](#customization)
5. [Troubleshooting](#troubleshooting)
6. [Uninstallation](#uninstallation-)

## Installation
### Via APT (recommended)

```bash
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

```bash
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:

```bash
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:

```bash
journalctl -u log2ram -e
```

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

You can also inspect the mount folder in RAM with:

```bash
# df -h | grep log2ram
log2ram          40M  532K   40M   2% /var/log
```
or also:

```bash
# mount | grep log2ram
log2ram on /var/log type tmpfs (rw,nosuid,nodev,noexec,relatime,size=40960k,mode=755)
```

If you do not get any line as response of these commands, something is not working. Refer to [this section](#is-it-working).

## Upgrading

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

## Customization

#### Variables
In the file `/etc/log2ram.conf`, there are five variables:

- `SIZE`: defines the size the log folder will reserve into the RAM (default is 40M).
- `USE_RSYNC`: (commented out by default = `true`) use `cp` instead of `rsync` (if set to `false`).
- `MAIL`: disables the error system mail if there is not enough place on RAM (if set to `false`).
- `PATH_DISK`: activate log2ram for other path than default one. Paths should be separated with a `;`.
- `ZL2R`: enable zram compatibility (`false` by default). Check the comment on the config file. See https://github.com/StuartIanNaylor/zram-swap-config to configure a zram space on your raspberry before enable this option.

#### 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:

```ini
[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 on 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):

```bash
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:

```bash
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!)_

```bash
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:

```bash
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:

```bash
sudo reboot
```

Wait until system reboots...

```bash
systemctl status log2ram
```

## Uninstallation :(

(Because sometimes we need it)

### Via APT

```bash
sudo apt remove log2ram
```

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

### Manually

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