Ajouter miscellaneous/readme_zfs_8gb_arc_limit.md

miscellaneous/readme_zfs_8gb_arc_limit.md

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+To limit the amount of RAM allocated to the ZFS ARC cache to 8 GB on TrueNAS, you can adjust a system configuration setting. Here’s how to do it:
+
+1. **Access the TrueNAS Interface**: Log in to the TrueNAS web interface.
+
+2. **Open the Shell**: Go to the top menu and click on **Shell** to open a terminal.
+
+3. **Modify the ZFS Configuration**:
+   - Enter the following command to limit the ARC to 8 GB:
+     ```shell
+     sysctl vfs.zfs.arc.max=8589934592
+     ```
+   - This command sets the maximum ARC size to 8 GB (8 GB in bytes = 8589934592).
+
+4. **Make the Change Persistent**:
+   - To ensure this setting applies on reboot, add it to the startup configuration file.
+   - Use the following command to append it to `sysctl.conf`:
+     ```shell
+     echo "vfs.zfs.arc.max=8589934592" >> /etc/sysctl.conf
+     ```
+
+5. **Restart the System**: It's recommended to restart TrueNAS to make sure the setting takes effect.
+
+This will effectively limit the ZFS ARC to 8 GB, allowing more RAM to be available for other processes.