**Use case**

Currently, `system.replicas` table has `total_replicas` and `active_replicas` columns which are useful to check/alert when some replicas are down. One problem, these columns are numbers. They tell when there is a problem, but you need to further check ZooKeeper or query all the nodes to detect what exact replicas (hosts) are down/inactive/have problems.

**Describe the solution you'd like**

Add a replicas column maybe as a map which would contain the replica name, and it's status. Or, add 2 array columns with `replica_names` and `active_replica_names`

**Alternative**

Something along the line

```sql
select path, value from system.zookeeper where path IN (
    select concat(path, '/', name) from system.zookeeper where path in (select concat(zookeeper_path, '/replicas') from system.replicas)
)
and name = 'is_active'
```
}
    ++current_table_fetches;
    SCOPE_EXIT({--current_table_fetches;});
    try
    {
        if (!fetchExistsPart(new_part_name, metadata_snapshot, fs::path(zookeeper_path) / "replicas" / source_replica, disk, path))
            return false;
    }
    catch (Exception & e)
    {
        if (e.code() == ErrorCodes::RECEIVED_ERROR_TOO_MANY_REQUESTS)
            e.addMessage("Too busy replica. Will try later.");
        tryLogCurrentException(log, __PRETTY_FUNCTION__);
        throw;
    }
    return true;
}
void StorageReplicatedMergeTree::executeDropRange(const LogEntry & entry)
{
    auto drop_range_info = MergeTreePartInfo::fromPartName(entry.new_part_name, format_version);
    getContext()->getMergeList().cancelInPartition(getStorageID(), drop_range_info.partition_id, drop_range_info.max_block);
    queue.removePartProducingOpsInRange(getZooKeeper(), drop_range_info, entry);
    
    
    
    
    
    auto metadata_snapshot = getInMemoryMetadataPtr();
    DataPartsVector parts_to_remove;
    {