Low cost Disaster Recovery for small businesses

[lucapsg]

The need is the classic one:
- file sharing between Windows machines in Workgroup environment (no AD)
- total data volume: 2TB
- average file size: 5MB
- RTO: <= 1 hour
- RPO: <= 1 hour
- maximum amount of data modified in 1 hour: 500MB
(RTO/RPO: https://en.wikipedia.org/wiki/Disaster_recovery)

I evaluated the ZFS replication between my two servers but, from what I understand, it must be considered a backup solution because the data on the target system is not available without intervening on the configuration (snapshot clone + smb share).

In my case, given the numbers, I think I have two alternatives: rSync or SyncThing.
Although SyncThing has the advantage of synchronizing data in "real-time" I would prefer rSync for its historical robustness.

The only doubt I have about rSync is the issue of permissions mentioned here: https://www.ixsystems.com/community...rmissions-support-for-windows-datasets.43973/

Other suggestions/ideas?
Thank you.

 

[danb35]

it must be considered a backup solution because the data on the target system is not available without intervening on the configuration

Could you explain your concern here a bit further? Because once you've replicated the data to the target system, it's "visible" there the same as it is on the primary.

 

[lucapsg]

Before trying the replication of ZFS, initially very attractive option, I looked for some information on the net and I saw this video https://youtu.be/Ge8eLR2FvDU?list=PLjGQNuuUzvmug2-LMfh43ehP9nt8gmCSf&t=323
The author states that by trying to work on the target system "You'll mess things up if you do. So there's not a way to do anything but read-only all the files that are on the destination of the replication."

It also says there is no "easy way to push data back".

My need instead is to have two synchronized systems, let's say one master and one slave, in order to switch to the other in case of malfunction.

So, if I understand correctly, ZFS replication is an exceptional tool to perform backups quickly and consistently, but still backups.

 

[danb35]

My need instead is to have two synchronized systems, let's say one master and one slave, in order to switch to the other in case of malfunction.

Yeah, if you need two-way replication, ZFS replication isn't the tool you're looking for.

 

[Patrick M. Hausen]

You could use two identical systems and replicate hourly. In case of failure of your primary you simply switch to the secondary. Once the former primary is repaired you make it the new secondary and re-initialise replication.

 

[lucapsg]

if you need two-way replication

No, I don't need a two-way synchronization, but a "primary-secondary" solution so that I can get back to work quickly, with minimal data loss and, possibly, without laborious interventions.

My need (and also that of many others) is best described on this thread https://www.ixsystems.com/community/threads/tips-for-a-redundant-freenas-server.71548/post-495254 and the solution suggested in post # 4 is exactly what I would like to achieve!

 

[lucapsg]

You could use two identical systems and replicate hourly. In case of failure of your primary you simply switch to the secondary. Once the former primary is repaired you make it the new secondary and re-initialise replication.

Yes, it would certainly be the best solution but, from what I have read, the replica is accessible in read-only mode.
So if the primary isn't usable, how do you enable write access on the secondary?