Survival

This tool simulates survivable failures in different homogeneous network topologies in a CockroachDB cluster.

This is done by simulating a single range and placing its replicas following the default diversity rules of Cockroach for maximum survivability. It then finds the maximum number of failures that the cluster can suffer without experiencing any unavailability.

There are 4 levels, Regions, Data Centers, Availability Zones and Nodes. But these are just placeholder names. They just represent the topology of the network and can fit whatever topology you have. If you want to ignore one level, just set it to 1.

You can select whichever failure mode you're interested in. Note that each failure mode occurs at a different level. Region failures show how many regions can fail, plus an extra lower level of failures. But it cannot be combined with Availability Zones failures. i.e.:

If you have a 3 Region, 2 DC per Region, 3 AZ per DC and 3 Nodes per AZ setup with a replication factor of 9x, you can survive the following scenarios:

• 1 Region and 1 additional AZ
• 1 DC and 1 additional AZ
• 4 Availability Zones
• 4 Nodes

But note that these are different scenarios and cannot overlap.

Limitations

Non-Homogeneous Clusters

This tool doesn't handle non-homogeneous clusters. If you are trying to look at the survivability of clusters that have a different number of DCs per region, or AZs per DC or nodes per AZ, then just pick the smallest number of the options. This should approximate the failures.

Constraints

If there are Required or Prohibited constraints (see here) on the cluster, you must treat each constraint zone differently as they will have different failure modes. Just setup the cluster as if the constraint is being followed. (i.e. remove any prohibited DC or only include required ones)

Per replica constraints cannot yet be handled by this tool, but it should provide a good starting point.

Instructions

Requirements

• Node v14.4.0 (or later)
• NPM v6.14.5 (or later)
• yarn v1.22.4 (or later)

To Run

1. clone the repo
2. install all dependencies: yarn
3. start the server yarn start

Bugs, improvements, etc

Please feel free to issue PRs and/or issues for bugs.

All help is appreciated!