NethServer HotSync Questions

I’m completely new to NethServer, and looking for some insight on some promising features I’ve come to notice.

I’ll be doing a multiple location site to site tunneled network connecting at least 3 buildings, and am curious how exactly your HotSync functionality works. Is it an automatic failover, or does it have to be manually switched over at the disconnection of the master.

Additionally, what is actually synced, is it just settings or is it content as well, for example, does nethserver-mail actually sync the mail accounts and all data, or does it just sync the settings associated with that service.

Does the same go for the NethServer Apache Hosts? Does it only sync configuration, or does that sync data as well. I assume Active Directory syncs, but I know from tests you can do a primary/secondary setup with those controllers over a site-to-site tunnel.

What would be the best way (in your opinion) to do a multiple site-to-site across a domain, where each building would be a failover point, or is that not possible for this software yet.

This is for an emergency services agency, so uptime, functionality, and reliability are absolutely crucial.

Your insight would be greatly appreciated.


Did you read documentation about hotsync? Which is now currently unsupported, but only from the community?


First of all: Welcome to the NethServer Community!

I’m plan and build networks for 20-30 SME clients. Among them are doctors, hotels and other clients, some need high availability, but all need a general high annual availibility, and fast disaster recovery, even if say a NAS or Server goes poof…

HotSync is a nice feature, but not quite “there” yet, and not the right foundation for high availability!

For starters, I’d suggest in virtualizing your environment on Proxmox, or something else. That’s one of the first steps in flexibility and availability. Live Backups, Snapshots and a lot of features in Proxmox gives peace of mind, once you’ve tried them out and see how well and fast it all works!

One of my larger clients has three sites, Zurich (35 users), Geneva (10 users) and Lugano (2 users). The head office is in Zurich, and all servers are in Zurich. The other two offices have NAS. All sites backup to the other two, so data is at all times available on three NAS.

Each NAS has an external USB3 Disk, with 8 generations of dtata/config of each NAS. This as a fast backup of the whole NAS - and as additional protection against Cryptolocker Ransomware. These external USB3 disks (Seagate Backup Hub plus with 8TB) are NOT accessible from the Network, only from the NAS. And the NAS are NOT AD integrated, and have a different admin password than the same AD user.

If you need help in planning a High Available System - I can help.

My 2 cents

I have read it. It does not mention that it’s unsupported. Nor does it answer any of the questions I posted, which is why I was curious.


It does state that HotSync still has BETA status! :slight_smile:


As I read at the linked docs, you have to do it manually

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.

Also at the linked documentation

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.

Perhaps @giacomo could help here.

Here’s the answer from the docs:

By default all data included in backup are synchronized every 15 minutes

You’d need to refer to the data backup page ( for more detail, but in short, yes, it’s content too.

I’m going to list the best ways, regardless of the cost.

If you’re talking about Active Directory domain, use 2 Windows Server Active Directory machines.
Regarding the HA in general, every application should implement it.

Finally, if you need a fully redundant infrastructure, you should think about a multi node cluster for virtual machines with a SAN which supports geographical replication.

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Clustered Proxmox with CEPH Storage would make do for a distributed, clustered HA SAN, and could also run easily 3 Microsoft AD Servers (current 2019…)

My 2 cents

That’s a really good suggestion! :wink:


Yeah, pity the entry level regarding hardware is a bit steep!

CEPH Hardware Requirements, Network: Starting with a 10 GBe LAN in your Network Center…

My 2 cents

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