topic Re: On a VMS cluster, how can you see on which node the Lock manager is running? in Operating System - OpenVMS

On a VMS cluster, how can you see on which node the Lock manager is running?

Jan van den Boogaard_1 — Wed, 28 Oct 2009 12:49:13 GMT

Question: On a VMS cluster, how can you see on which node the Lock manager is running?

Re: On a VMS cluster, how can you see on which node the Lock manager is running?

Volker Halle — Wed, 28 Oct 2009 12:55:13 GMT

Jan,

it's called DLM - the Distributed Lock Manager ! It's running everywhere...

On a multi-CPU system, you could dedicate ONE CPU to run the lock-manager code and then you would see a LCKMGR_SERVER 'process' always in COM state on that CPU. This feature is called the 'Dedicated CPU Lock Manager'. But if that node is member of a cluster, the 'lock manager' will run on the other nodes as well.

What's the problem ?

Volker.

Re: On a VMS cluster, how can you see on which node the Lock manager is running?

Jan van den Boogaard_1 — Wed, 28 Oct 2009 14:24:55 GMT

Hallo Volker,

We use Rdb on a cluster and were looking into the possibility to let batchjobs that use the Rdb database , run on the node where the DLM has the highest load, to avoid thrashing of locks between the lock managers on the different nodes.
To do so, we must somehow measure where the DLm has the highest load.

Re: On a VMS cluster, how can you see on which node the Lock manager is running?

Volker Halle — Wed, 28 Oct 2009 15:12:16 GMT

Jan,

in this case, you need to find out, where the resource tree of the database is being mastered. Then run your batch jobs at that node...

ANAL/SYS
SDA> LCK SHOW ACT ! available since V7.2-1H1

This will show the most active resources.

There is also SYS$EXAMPLES:RDB$SDA.COM. You can use this procedure to build a RDB$SDA.EXE SDA extension. Then use

$ DEF RDB$SDA dev:RDB$SDA.EXE
$ ANAL/SYS
SDA> RDB SHOW ACTIVE_DB

This would find the RDB database resource trees and display the desired information. You would be interested in the nodename displayed in the 'Node' column. This is the node mastering the resource tree. If you run your batch jobs on that node, locking operations will be local and a lot faster than 'remote' locking operations.

You can monitor distributing locking operations with MONITOR DLOCK. You want 'local' ENQs/CVTs/DEQs as opposed to incoming or outgoing lock operations.

Volker.

Re: On a VMS cluster, how can you see on which node the Lock manager is running?

Jan van den Boogaard_1 — Wed, 28 Oct 2009 15:23:00 GMT

Volker,

This is the information we need !! Thanks a lot!