no more servers

[BT7268]

hi:
I have deployed a cluster with 1 lead ,2 locators and 27 data servers.
But when i add one or more data servers to the cluster, the create table operation cost so much time, about 1000+sec.

snappy-sql> CREATE TABLE test(col1 int, col2 varchar(25)) using column options();
ELAPSED TIME = 1311210 milliseconds

And during this time, when i execute sql, i got such an error

snappy-sql> select * from test;
ERROR 40XL1: (SQLState=40XL1 Severity=30000) (Server=e8dfc357/11.40..[1527] Thread=ThriftProcessor-127) A lock could not be obtained within the time requested
snappy-sql> select * from test_1;
ERROR 40XL1: (SQLState=40XL1 Severity=30000) (Server=e8dfc357/11.40..[1527] Thread=ThriftProcessor-127) A lock could not be obtained within the time requested

How can I avoid such error or add more data servers?