SDS_ALTERNATE configuration parameter

Use the SDS_ALTERNATE configuration parameter to define an alternate means of communication between the primary server and SD secondary servers in a high-availability cluster.

onconfig.std value
NONE (No SD secondary server alternate communication path is configured.)
values
The name of the blobspace that is to be used as the alternate communication path between the primary server and SD secondary servers.
takes effect
After you edit your onconfig file and restart the database server.
When you reset the value dynamically in your onconfig file by running the onmode -wf command.
When you reset the value in memory by running the onmode -wm command.

Usage

You set the SDS_ALTERNATE configuration parameter and create a shared blobspace to allow the primary server and all SD secondary servers in a high-availability cluster to use an alternate communication path in the event the network is unavailable between the primary server and the SD secondary servers. When an SD secondary server is about to failover and become the primary server, but TCP/IP communication is unavailable, the shared blobspace set by the SDS_ALTERNATE configuration parameter is used communicate the shut-down procedure to the original primary.

Set the SDS_ALTERNATE configuration parameter to the same value on the primary server and on all SD secondary servers.

Before setting the SDS_ALTERNATE configuration parameter, you must create the shared blobspace on the primary server. For example, to create a blobspace named sds_alt_comm enter the following command on the primary server:

onspaces -c -b sds_alt_comm -g <pagesize> -p <path> -o <offset> -s <size>

Run the following command to switch to the next logical log file so that the newly created blobspace is usable:

onmode -l

On each of the SD secondary servers in the high-availability cluster, set the SDS_ALTERNATE configuration parameter to point to the blobspace on the primary server.

SDS_ALTERNATE sds_alt_comm

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