HotSync should be considered a beta release. Please test it on your environment before using in production.
HotSync aims to reduce downtime in case of failure, syncing your NethServer with another one, that will be manually activated in case of master server failure.
Normally, when a hardware damage occurs, the time needed to restore service is:
- fix/buy another server: from 4h to 2 days
- install OS: 30 minutes
- restore backup: from 10 minutes to 8 hours
In summary, users are able to start working again with data from the night before failure after a few hours/days. Using hotsync, time 1 and 3 are 0, 2 is 5 minutes (time to activate spare server). Users are able to start working again in few minutes, using data from a few minutes before the crash.
By default all data included in backup are synchronized every 15 minutes. MariaDB databases are synchronized too, unless databases synchronization isn’t disabled. Applications that use PostgreSQL are synchronized (Mattermost, Webtop5) unless databases synchronization isn’t disabled.
- MASTER is the production system SLAVE is the spare server
- SLAVE is switched on, with an IP address different than MASTER
- Every 15 minutes, MASTER makes a backup on SLAVE
- An email is sent to root (admin if mail server is installed)
Install nethserver-hotsync on both MASTER and SLAVE, execute from command line:
yum install nethserver-hotsync
<PASSWORD> must be the same on master and slave.
If mysql or postgresql are installed, they will be synchronized by default. To disable databases sync
Hotsync is enabled by default. To disable it:
and to re-enable it:
Restore: put SLAVE in production¶
The following procedure puts the SLAVE in production when the master has crashed.
switch off MASTER
if the SLAVE machine must run as network gateway, connect it to the router/modem with a network cable
on SLAVE, if you are connected through an ssh console, launch the
screencommand, to make your session survive to network outages:
[[email protected]]# screen
on SLAVE launch the following command, and read carefully its output
[[email protected]]# hotsync-promote
go to Server Manager, in page
Networkand reassign roles to network interfaces as required
launch the command
[[email protected]]# /sbin/e-smith/signal-event post-restore-data
update the system to the latest packages version
[[email protected]]# yum clean all && yum -y update
if an USB backup is configured on MASTER, connect the backup HD to SLAVE
- nethserver-freepbx > 14.0.3
- nethserver-webtop5 (z-push state is not synchronized)