Meta server: another truncate() optimization: search for the chunk with offset equal or larger than requested, and if found use the file attribute pointer stored in the chunk map entry. Optimize getLastChunkInfo by using b+tree search if the last chunk offset is more than 8 chunks apart from the first chunk, and the number of chunks in the file is greater than 8. Change get alloc with start offset [only] used by get layout to return chunks with offset equal or greater than the specified offset. Minor LayoutManager::UpdateDelayedRecovery() optimization: use scratch vector to retrieve chunks information.