greenplum 安装异常 psql: FATAL: DTM initialization

greenplum 安装错误 psql: FATAL: DTM initialization:
20111108:17:56:37:gpstart:mdw:gpadmin-[INFO]:-Successfully started 4 of 4 segment instances 
20111108:17:56:37:gpstart:mdw:gpadmin-[INFO]:-----------------------------------------------------
20111108:17:56:37:gpstart:mdw:gpadmin-[INFO]:-Starting Master instance mdw directory /gpmaster/gpseg-1 
20111108:17:56:38:gpstart:mdw:gpadmin-[INFO]:-Command pg_ctl reports Master mdw instance active
20111108:17:56:39:gpstart:mdw:gpadmin-[INFO]:-Database successfully started with no errors reported
20111108:17:56:39:gpinitsystem:mdw:gpadmin-[INFO]:-Completed restart of Greenplum instance in production mode
20111108:17:56:39:gpinitsystem:mdw:gpadmin-[INFO]:-Loading gp_toolkit...
psql: FATAL:  DTM initialization: failure during startup/recovery, retry failed, check segment status (cdbtm.c:1326)
20111108:17:56:42:gpinitsystem:mdw:gpadmin-[FATAL]:-Failed to retrieve rolname. Script Exiting!
数据库己经成功安装但是出现这个错误不能执行psql命令。。求解
psql: FATAL:  DTM initialization: failure during startup/recovery, retry failed, check segment status (cdbtm.c:1326)
------解决方案--------------------
原来是iptables没关