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--- en:linux:nfs_unique_machineid [2020/05/06 03:21]
alex created
+++ en:linux:nfs_unique_machineid [2020/05/06 03:59] (current)
alex
@@ Line 1: / Line 1: @@
 ====== Unique machine ID for nfs root systems ======
+When multiple hosts running systemd share the same NFS root, they will also share the same machine-id.  This can cause issues, especially with journald.  Journald logging can be disabled by deleting ''/var/log/journal'' which solves most of the problems, but a better solution is to use unique machine-id values on all of the hosts.  Modern motherboards provide a unique UUID accessible via DMI, so a reasonable option is to write this out to /run during boot and point systemd at that as the machine-id.  Here is a simple way to set that up.
+Create the file ''/etc/initramfs-tools/scripts/init-top/machineid'':
+<code bash machineid>
+#!/bin/sh -e
+PREREQS=""
+prereqs() { echo "$PREREQS"; }
+case "$1" in
+    prereqs)
+    prereqs
+    exit 0
+    ;;
+esac
+# write sanitized motherboard UUID to /run/machine-id
+sed 's/-//g' /sys/class/dmi/id/product_uuid > /run/machine-id
+# requires the following symbolic links:
+# ln -sf /run/machine-id /etc/machine-id
+# ln -sf /run/machine-id /var/lib/dbus/machine-id
+</code>
+Rebuild the initramfs (for example ''update-initramfs -u'') and replace ''/etc/machine-id'' and ''/var/lib/dbus/machine-id'' with symlinks to ''/run/machine-id''.