Meta server: revise version change and version change roll back, add special version range check variant for stable chunks with partial chunk inventory update protocol. Declare chunks stale in the case if version change fails. Take into the account chunk version roll back when verifying stable chunks with partial chunk inventory / resume hello. Change pending version change to declare failure only in the case if write lease exists at the time of completion in the case of pending replica addition. Perform version roll back in the case of chunk re-allocation failure only with the chunk servers that were participating in re-allocation, in order to prevent sporadic version change failures that could result in chunk replica loss. Optimize chunk inventory processing by avoiding chunk version roll back lookup in the case if chunk version matches.
Chunk server implement special version of stable chunk version range verification with chunk version change RPC.