What is the zNode data limit size for Apache ZooKeeper?

1GB? 10MB? 1KB?

zNode Limit = 1MB.

This is the default size of a single zNode or key/value pair within ZooKeeper.  It should be noted that both the Key and the Value are combined into this equation.  ZooKeeper is designed as a high read, high throughput system for small keys.  It is not designed as a large data store to hold very large data values.  As such this 1MB value is a default config option and can be overridden.  It is not advised to do so – but increasing the size a little bit will probably not damage your system (it all depends on your unique access patterns and these changes should be made with care and at your own risk).