The gp_segment_configuration table contains information about mirroring and segment configuration.
sachi=# \d gp_segment_configuration
Column | Type | Modifiers
dbid | smallint | not null
content | smallint | not null
role | "char" | not null
preferred_role | "char" | not null
mode | "char" | not null
status | "char" | not null
port | integer | not null
hostname | text |
address | text |
replication_port | integer |
san_mounts | int2vector |
"gp_segment_config_content_preferred_role_index" UNIQUE, btree (content, preferred_role), tablespace "pg_global"
"gp_segment_config_dbid_index" UNIQUE, btree (dbid), tablespace "pg_global"
dbid => The unique identifier of a segment (or master) instance
content -> The content identifier for a segment instance. A primary segment instance and its corresponding mirror will always have the same content identifier. For a segment the value is from 0-N, where N is the number of primary segments in the system.For the master, the value is always -1.
role=> The role that a segment is currently running as. Values are p (primary) or m (mirror).
preferred_role=>The role that a segment was originally assigned at initialization time. Values are p (primary) or m (mirror).
mode=>The synchronization status of a segment with its mirror copy. Values are s (synchronized), c(change logging), or r (resyncing).
status=>The fault status of a segment. Values are u (up) or d (down).
port=>The TCP port the database server listener process is using.
hostname=>The hostname of a segment host.
address=> The hostname used to access a particular segment on a segment host. This value may be the same as hostname in systems
upgraded from 3.x or on systems that do not have per-interface hostnames configured.
replication_port=> The TCP port the file block replication process is using to keep primary and mirror segments synchronized.
san_mount=> An array of references to the gp_san_configuration table. Only used on systems that were initialized using sharred storage.