Excuting query during failover in scale out

-- Scale Out  environment

UCS Appliance * 3 Node

one node - one volumn

Node 1 - Master
Node 2 - Slave
Node 3 - Standby

we made a partition table "SALES_P" of Roundrobin Partition type
Partition Data is distributed to Node1 and Node2
we've been testing as following

Senario

1. executing query in MASTER node
    SELECT p.prod_subcategory, SUM(s.amount_sold)
FROM   sales_p s, products p, times t, customers c
WHERE  s.time_id=t.time_id AND s.cust_id=c.cust_id
GROUP BY p.prod_subcategory, t.calendar_month_desc, c.cust_city

2. executing reboot OS in SLAVE node

3. error
The following message is displayed in MASTER node

     Could not execute 'SELECT p.prod_subcategory, t.calendar_month_desc, c.cust_city,
     SUM(s.amount_sold), ...' in 13.473 seconds . SAP DBTech JDBC: [2048]: c
     olumn store error: search table error:  [2613] executor: communication problem

i don't kno why query result is not displayed