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The CASGLM.LCK file

The CASGLM.LCK file stores important information about the state of an Enterprise Server Cluster.

Overview

When an Enterprise Server Cluster starts for the first time, there is no static information that defines its members. The members are dynamically added as they start, provided they have been configured to be part of such a cluster - via the ES_CLUSTER environment variable and sharing of the CATALOG.DAT and DADL.

When an Enterprise Server Cluster is started for the first time, the GLM creates a file called CASGLM.LCK in the same folder as the system catalog. At startup, cluster clients read the CASGLM.LCK file to retrieve the information stored in a specific, GLM record, of the file. Clients are then able to communicate with the GLM and send requests, so that the GLM becomes aware of them and writes a record for each cluster member.

The file also contains information used in recovery situations.

File structure

CASGLM.LCK is created in the same folder as the system catalog, and is a byte-stream file. To make it viewable, CRLF characters have been added - but it should not be updated or edited, which may lead to unexpected results. It can be deleted.

Each record is composed of six parameters:
Table 1. Structure of CASGLM.LCK records
Parameter name Parameter value Notes
G= or C= GLM APPLID

Cluster CLIENT APPLID

The GLM uses the client APPLID to request information such as its lock list in a recovery situation.

The client uses the GLM APPLID to dynamically create and initiate an ISC listener and ISC connection to the GLM.

T= GLM Timeout
S= Member SYSID Clients use GLM SYSID to dynamically create and initiate an ISC listener and ISC connection to the GLM
A= Y or N Y for active, N for inactive
P= nnnnn Port used by the ISC listener
H= * or the value of the environment variable: ES_HOSTNAME_TO_USE TCP/IP address of the Enterprise Server Cluster member
The following represents sample CASGLM.LCK contents for an Enterprise Server Cluster with five members:
G=ESCLMGR  T=00060 S=MST1 A=Y P=52454 H= nwb-srv-test77                                                                                                                                                                                                                                                       
C=ESCLSLV1 T=00060 S=SLV1 A=Y P=53608 H=nwb-srv-test68                                                                                                                                                                                                                                                       
C=ESCLSLV2 T=00060 S=SLV2 A=Y P=53618 H= nwb-srv-test98                                                                                                                                                                                                                                                       
C=ESCLSLV3 T=00060 S=SLV3 A=Y P=53623 H= nwb-srv-test67
C=ESCLSLV4 T=00060 S=SLV3 A=Y P=53623 H= nwb-srv-test99
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