The vBucketMap value within the returned JSON describes the vBucket organization. For example:

"serverList":["10.1.4.11:11210","10.1.4.12:11210"], "vBucketMap":[[0,1],[1,0],[1,0],[1,0],:,[0,1],[0,1]]

The vBucketMap is zero-based indexed by vBucketId. So, if you have a vBucket whose vBucketId is 4, you'd look up vBucketMap[4]. The entries in the vBucketMap are arrays of integers, where each integer is a zero-based index into the serverList array. The 0th entry in this array describes the primary server for a vBucket. Here's how you read this stuff, based on the above config:

The vBucket with vBucketId of 0 has a configuration of vBucketMap[0], or[0, 1]. So vBucket 0's primary server is at serverList[0], or 10.1.4.11:11210.

While vBucket 0's first replica server is at serverList[1], which is 10.1.4.12:11210.

The vBucket with vBucketId of 1 has a configuration of vBucketMap[1], or[1, 0]. So vBucket 1's primary server is at serverList[1], or 10.1.4.12:11210. And vBucket 1's first replica is at serverList[0], or 10.1.4.11:11210.

This structure and information repeats for every configured vBucket.

If you see a -1 value, it means that there is no server yet at that position. That is, you might see:

"vBucketMap":[[0,-1],[0,-1],[0,-1],[0,-1],:]

Sometimes early before the system has been completely configured, you might see variations of:

"serverList":[], "vBucketMap":[]