MIM - Catalog Sharing when cached using VLF

Products

• MIM Data Sharing (MII)

Issue/Introduction

Current catalog handling is using all ISC and not utilizing VLF. Planning to start using VLF as per IBM recommendations.

Does MIM have an issue if Catalogs were cached using VLF instead of our current ISC (in-storage catalog).

In another words, will MIM have any issues sharing catalogs across SYSPLEX’s and using VLF?"

 

 

Environment

Release : 12.5
Component : MIM

Resolution

MIM does not have any known issues with this. We have not had any of our customers report a problem in this area. We have many customers converting catalog reserves and VLF has been around for a long time..

• MIM does not have any special catalog processing or intercepts.
• MIM's job is to send the ENQs from one system to all the external systems within the MIMplex.
• MIM does not treat catalog ENQs any different than other ENQs.

Additional Information

Here's IBM's recommendation from a Heath Check underway:

COFVLF
• There are additional opportunities to benefit from VLF (both of these are in use in the UPLEX1 (see UBS.UPLEX1.PU01.SYS5.PARMLIB(COFVLF00), so they are not new or untested).
• The IGGCAS class moves cached catalog records from the CATALOG address space in-storage catalog (ISC) to VLF.
• IBM recommends that all catalogs other than the Master Catalog should be cached using VLF rather than ISC.
• The catalogs that will use VLF must be listed in the COFVLFxx member, in the IGGCAS class.
• See Tuning Letter article ‘RLS-Managed Catalogs’ for more information about ISC and VLF.