I'm setting up a high-availability failover cluster by directly connecting two Hyper-V or ESXi servers to a shared SAN storage device. Is it necessary to set up a witness node to prevent split-brain scenarios? Thanks in advance for your help!
5 Answers
In Linux clustering setups, they often use a quorum disk for similar purposes. There might be an equivalent for Microsoft that could help you out. It’s worth looking into!
Absolutely! They’re basically the same concept.
If you're working with an even node cluster, having a witness is a must! Ideally, something like a cloud witness would work well, but there are various setups to consider that can fit your needs.
You can use a small 1GB disk on the SAN as a witness. This is a simple solution for managing cluster quorum without needing a dedicated VM.
Had a coworker who jokingly suggested using God as a witness. Spoiler: it didn’t work out as a tiebreaker!
A witness is crucial to avoid chaos in case of disconnection. If both servers think they’re the master, you can end up with a situation where both are making conflicting changes, which leads to data corruption. The witness gives a clear majority to one side, so only that server continues to take resources for clients.
Yes, having an even number of nodes like this definitely requires a witness. It helps prevent the split-brain problem by ensuring only one server can make changes if they lose communication with each other.
Yeah, MS clustering can also utilize a shared quorum disk as a witness!