Setting up replication

[zenn68]

Other than the official documentation is there any other good resources for setting up replication between 2 boxes. Going over different configuration options, what to use, different setup scenarios, Best practices.

 

[Basil Hendroff]

Good question. If it's out there, I haven't seen it yet. I guess that's because it's not on the agenda for the majority of FreeNAS users so it has a limited audience. Some ideas based on my own experiences follow.

Business considerations:
Data types fall broadly into two categories:
Type A: Critical and/or dynamic data, smaller data chunks
Type B: Non-critical and/or slowly varying data, larger data chunks

Technical considerations:
- Bandwidth and Replication
- Periodic snapshot frequency and retention
- Data

Bandwidth and Replication
Assuming there is limited bandwidth between the two boxes, I'd tend to move the replication of Type B data to off-peak hours, though I'd make sure that replication window doesn't overlap with scrubs and extended SMART tests, which for me occur during the wee hours of the morning. I tend to allow Type A data to replicate across peak hours as well as off-peak hours, with the same caveat on the maintenance window.

Periodic snapshot frequency and retention
I have a higher snapshot frequency during peak times (for Type A data) and a lower snapshot frequency off-peak (both Type A and B data). A higher snapshot frequency also lends itself nicely to setting up shadow copies on FreeNAS shares containing user data (a subset of Type A).

Snapshot retention requires some thought. I've got mine set to 2 weeks. However, when planning extended leave, I might alter the retention period to a few days longer than the length of my leave. This will help provide a degree of immunity against cryptolocker type viruses.

Data
The more you're able to compartmentalise Type A and B data across datasets, the more granular the control you have on how those datasets get snapshotted and replicated.