VVR: VxVM 6.2.1 VVR nmcom_max_connections setting is not maintained after disconnect/reconnect of rlink

Problem

The VVR (Veritas Volume Replicator) Primary node does not maintain the number of TCP connections set in the nmcom_max_connections setting after the rlink does a disconnect and reconnect of the rlink.

Cause

VVR 6.2.1 does not have a setting to force the nmcom_max_connections to be used during rlink disconnect/reconnect operations.  After a rlink disconnect, VVR in 6.2.1 reverts back to auto-tuning the number of TCP connections during the reconnect operation.

Solution

Veritas has identified this as an issue for customer and has created a patch to add a new tunable to force VVR to always use the nmcom_max_connections value during rlink reconnect operations.  Use these steps to set the 2 tunable values:

1. Set nmcom_max_connections to the desired value.
   1. example:  vxtune nmcom_max_connections 16
2. Set vol_vvr_force_connections to 1 to enable force of max tcp connections.
   1. example:  vxtune vol_vvr_force_connections 1

To disable the force max tcp connections tunable, set vol_vvr_force_connections to 0.

Patches are currently available for RHEL6 and RHEL7.

Please contact Veritas Technical Support to download Private hot-fix vm-rhel6_x86_64-HotFix-6.2.1.8203 or vm-rhel7_x86_64-HotFix-6.2.1.8203.

Reference Escalation: STESC-3402