**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'
```
const String & source_replica,
    const String & new_part_name,
    const DiskPtr & disk,
    const String & path)
{
    if (source_replica.empty())
    {
        LOG_INFO(log, "No active replica has part {} on shared storage.", new_part_name);
        return false;
    }
    const auto storage_settings_ptr = getSettings();
    auto metadata_snapshot = getInMemoryMetadataPtr();
    if (storage_settings_ptr->replicated_max_parallel_fetches && total_fetches >= storage_settings_ptr->replicated_max_parallel_fetches)
    {
        throw Exception("Too many total fetches from replicas, maximum: " + storage_settings_ptr->replicated_max_parallel_fetches.toString(),
            ErrorCodes::TOO_MANY_FETCHES);
    }
    ++total_fetches;
    SCOPE_EXIT({--total_fetches;});
    if (storage_settings_ptr->replicated_max_parallel_fetches_for_table
        && current_table_fetches >= storage_settings_ptr->replicated_max_parallel_fetches_for_table)
    {
        throw Exception("Too many fetches from replicas for table, maximum: " + storage_settings_ptr->replicated_max_parallel_fetches_for_table.toString(),
            ErrorCodes::TOO_MANY_FETCHES);