**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'
```
else
    {
        ops.emplace_back(zkutil::makeCreateRequest(
            fs::path(replica_path) / "parts" / part->name,
            "",
            zkutil::CreateMode::Persistent));
        ops.emplace_back(zkutil::makeCreateRequest(
            fs::path(replica_path) / "parts" / part->name / "columns",
            part->getColumns().toString(),
            zkutil::CreateMode::Persistent));
        ops.emplace_back(zkutil::makeCreateRequest(
            fs::path(replica_path) / "parts" / part->name / "checksums",
            getChecksumsForZooKeeper(part->checksums),
            zkutil::CreateMode::Persistent));
    }
}
ReplicatedMergeTreeAddress StorageReplicatedMergeTree::getReplicatedMergeTreeAddress() const
{
    auto host_port = getContext()->getInterserverIOAddress();
    auto table_id = getStorageID();
    ReplicatedMergeTreeAddress res;
    res.host = host_port.first;
    res.replication_port = host_port.second;
    res.queries_port = getContext()->getTCPPort();
    res.database = table_id.database_name;
    res.table = table_id.table_name;
    res.scheme = getContext()->getInterserverScheme();
    return res;
}
ActionLock StorageReplicatedMergeTree::getActionLock(StorageActionBlockType action_type)