Manually Resynchronize a DSA in a Multiwrite System

Products

• CA Directory

Issue/Introduction

CA Directory offers a set of powerful "Directory Replication" feature. At times, however, a DSA that is participating in a Multiwrite system can be brought down for an extended period of time and causes a data out-of-sync situation and worse prevent the out-of-sync DSA from starting.

This Directory Replication feature can be used to improve the availability and/or the performance of the directory. The more commonly used approaches are multiwrite replication and multiwrite replication with DISP recovery. See

Directory Replication

for more details.

 

Environment

Directory 14.1

Component: CA Directory

Cause

A DSA that is participating in a Multiwrite system was brought down for an extended period of time and caused it to become out-of-sync and sometimes fail to start.

Resolution

Since there are two flavors of a Multiwrite system, we first need to correctly identify the type of the multiwrite system and then to apply the right method to bring the out-of-sync DSA back up and back in sync. A multiwrite replication with DISP recovery system starts with a simple multiwrite replication system that is easily identified and enabled through the dsa-flag in the shared knowledge as the following example:

set dsa dsaname =
{
...
dsa-flags = multi-write, no-service-while-recovering ...
...
};

A DSA participates in a multiwrite replication with DISP recovery needs to have the following:

set multi-write-disp-recovery = true;

This setting is often set in the DSA dxi file. But can also exists in other configuration files the dxi file sources in. The following commands can help you locate them and see how they apply to your DSA:

cd "$DXHOME/config"
find . -type f -exec grep multi-write-disp-recovery {} +

For a running DSA, you can also use the following Console command, telnet to its console port, to check its multi-write-disp-recovery setting:

get dsp;

 

Manually Resynchronize a DSA in a Multiwrite System W/O DISP Recovery

Once confirmed your DSA is in a Multiwrite system without DISP recover, you can follow the "How to Perform a Disaster Recovery" section in the following link:

Enabling Transaction Log and Data Recovery

Manually Resynchronize a DSA in a Multiwrite System With DISP Recovery

Once confirmed your DSA is in a Multiwrite system with DISP recovery, you can use the following link to manually resynchronize an out-of-sync DSA:

Topology Sample and Disaster Recovery