How To Manage the Cluster Health Monitor ( CHM ) Repository

Where is Cluster Health Monitor (CHM) Repository ?

In 11.2, the CHM repository is stored in a Berkley Database . The default location of the CHM repository is $GI_HOME/crf/db.

In 12.1, the CHM repository is hosted in the Grid Infrastructure Management Repository (GIMR). The default location for GIMR is stored in the ASM diskgroup which stores the OCR and voting disk .

What is the recommended CHM data retention ?

Oracle Support recommends that the CHM repository be sized according to 72 hours ( 259,200 seconds )(three days) of data retention (e.g.., one weekend worth).

What is the minimum size of  CHM repository ?

For 11.2 GI, one day of data retention for each node requires  867 MB around. So the size of the CHM repository needed to retain 72 hours of data would be as follows:

~72 hours of CHM data retention = NumberOfNodes * 3Days * 867 MB

So for a 2 nodes cluster :

~72 hours of CHM data retention = 2 ( nodes ) * 3 ( days ) * 867 ( per day per node )(5202 MB)

For 12.1, one day of data retention for each node requires 750 MB around, so the size of the CHM repository needed to retain 72 hours of data would be as follows:

~72 hours of CHM data retention = NumberOfNodes * 3Days * 750 MB

So for a 2 node cluster

~72 hours of CHM data retention = 2 ( nodes ) * 3( days ) * 750 ( per day per node ) (4500 MB)

How to see the current CHM repository retention in seconds ?

[grid@racnode1 ~]$ /u01/app/12.1.0/grid/bin/oclumon manage -get repsize

CHM Repository Size = 272580 seconds

How to resize the CHM Repository retention ?

For 11.2 GI:

To determine the current location of the CHM repository:

$oclumon manage -get reppath

  $ oclumon manage -repos reploc path* -maxspace 5202 

For 12.1:

To resize the CHM Repository with one command to result in 3 days retention, eg., for a 2  nodes cluster:

$ oclumon manage -repos changerepossize 4500

How to verify the change in repository size has met the desired retention ?

In 12.1.0.1

$ oclumon manage -repos changeretentiontime 260000

This command does not make any changes. It is more like a “what-if”, ie., what if I wanted to change the retention time, how much space would be required ?

In 12.1.0.2 the syntax was changed and should be used as follows :

[grid@racnode1 ~]$ oclumon manage -repos checkretentiontime 260000

The Cluster Health Monitor repository can support the desired retention for 2 hosts