From 08969b8fa0966cd5f57edad9fb90e282c6745e24 Mon Sep 17 00:00:00 2001 From: Chuck Litzell Date: Fri, 26 Apr 2019 11:47:41 -0500 Subject: [PATCH] Remove implication that transactions restart themselves after segment failure. (#7534) --- .../topics/g-overview-of-segment-mirroring.xml | 8 ++++++-- gpdb-doc/dita/admin_guide/managing/highavail.xml | 11 +++++++---- 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/gpdb-doc/dita/admin_guide/highavail/topics/g-overview-of-segment-mirroring.xml b/gpdb-doc/dita/admin_guide/highavail/topics/g-overview-of-segment-mirroring.xml index c58f482a48..b8a6e777ea 100644 --- a/gpdb-doc/dita/admin_guide/highavail/topics/g-overview-of-segment-mirroring.xml +++ b/gpdb-doc/dita/admin_guide/highavail/topics/g-overview-of-segment-mirroring.xml @@ -8,8 +8,12 @@ instances: primary and mirror. Each primary segment has one corresponding mirror segment. A primary segment instance receives requests from the master to make changes to the segment data and then replicates those changes to the corresponding - mirror. If a primary segment becomes unavailable, database queries fail over to the - mirror segment.

+ mirror. If Greenplum Database detects that a primary segment has failed or become + unavailable, it changes the role of its mirror segment to primary segment and the role + of the unavailable primary segment to mirror segment. Transactions in progress when the + failure occurred roll back and must be restarted. The administrator must then recover + the mirror segment, allow the mirror to syncronize with the current primary segment, and + then exchange the primary and mirror segments so they are in their preferred roles.

If segment mirroring is not enabled, the Greenplum Database system shuts down if a segment instance fails. Administrators must manually recover all failed segments before Greenplum Database operations can resume.

diff --git a/gpdb-doc/dita/admin_guide/managing/highavail.xml b/gpdb-doc/dita/admin_guide/managing/highavail.xml index 84da5d579c..7c5a1714da 100644 --- a/gpdb-doc/dita/admin_guide/managing/highavail.xml +++ b/gpdb-doc/dita/admin_guide/managing/highavail.xml @@ -253,10 +253,13 @@ mirror3=3:sdw2:sdw2-2:52002:53002:54002:/gpdata/mir1/gp3 Detecting a Failed Segment

With mirroring enabled, Greenplum Database automatically fails over to a mirror segment - when a primary segment goes down. Provided one segment instance is online per portion of - data, users may not realize a segment is down. If a transaction is in progress when a fault - occurs, the in-progress transaction rolls back and restarts automatically on the - reconfigured set of segments.

+ when a primary segment goes down. The mirror segment assumes the role of the primary segment + and the failed primary segment becomes the mirror. Transactions in progress when a fault + occurs roll back and must be restarted. When restarted the transactions run on the new + primary segment.

+

To return the Greenplum Database cluster to full redundancy and balance, an administrator + recovers the down mirror segment and exchanges the roles of the primary and mirror + segments so that both segments are in their preferred roles.

If the entire Greenplum Database system becomes nonoperational due to a segment failure (for example, if mirroring is not enabled or not enough segments are online to access all user data), users will see errors when trying to connect to a database. The errors returned -- GitLab