zfsonlinux/zfs/debian/zfsutils-linux.postinst
Stoiko Ivanov 5b9cd1ad57 zfsutils-linux: persist hostid in postinst script
/etc/hostid does not exist on a minimal debian system.
ZFS reads its contents for MMP (zpool property multihost set to on), and needs
the value to be stable.
Before the SPL->ZFS merge the spl userspace package wrote the file (by parsing/
mangling the output of hostid (1)) Since ZFS provides the zgenhostid script,
which creates a random 4 byte hostid and writes it to /etc/hostid, we use that
instead. (hostid (1) default to mangling a configured ip of the system, which
can be the same across multiple installs (install happens with the same ip)

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
2019-05-24 11:44:34 +02:00

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#!/bin/sh
set -e
# The hostname and hostid of the last system to access a ZFS pool are stored in
# the ZFS pool itself. A pool is foreign if, during `zpool import`, the
# current hostname and hostid are different than the stored values thereof.
#
# The only way of having a stable hostid is to define it in /etc/hostid.
# This postinst helper will check if we already have the hostid stabilized by
# checking the existence of the file /etc/hostid to be 4 bytes at least.
# If this file don't already exists on our system or has less than 4 bytes, then
# a new (random) value is generated with zgenhostid (8) and stored in
# /etc/hostid
if [ ! -f /etc/hostid ] || [ "$(stat -c %s /etc/hostid)" -lt 4 ] ; then
zgenhostid
fi
#DEBHELPER#