Recovering a Failed Segment
If the master cannot connect to a segment instance, it marks that segment as down in the
Greenplum Database system catalog. The segment instance remains offline until an administrator
takes steps to bring the segment back online. The process for recovering a failed segment
instance or host depends on the failure cause and whether or not mirroring is enabled. A
segment instance can be unavailable for many reasons:
- A segment host is unavailable; for example, due to network or hardware
failures.
- A segment instance is not running; for example, there is no
postgres database listener process.
- The data directory of the segment instance is corrupt or missing; for
example, data is not accessible, the file system is corrupt, or there is a disk
failure.
shows the high-level steps for each
of the preceding failure scenarios.
Segment Failure Troubleshooting Matrix