Why defined MAX_CONFIGURED_PACKAGES

[Ralf_S]

Hi,

Ever since I have been working with ServiceGuard, I have worked on clusters with MAX_CONFIGURED_PACKAGES set to the maximum.

On the other hand, nearly all clusters, I have seen but not administrated, had this value set to a quiet narrow value of somewhere between 5 and 20.

The "largest" cluster I have ever seen had 28 packages running on two nodes.

Now, I have a single questions to the experts:

What is the drawback of setting a big value for MAX_CONFIGURED_PACKAGES? I don't expect a bottleneck of system resources to be any reason for reducing this value today or even ten years in the past.

Is there a reasonable argument for setting this value besides "setting any parameter to about the value, that is required on a specific system and not much higher"?

Any response will be greatly appreciated.

Regards

Ralf

[Duncan Edmonstone]

Ralf,

You have to remember that Serviceguard is an old product - going back about 20 years. Back then memory was very expensive, and you saved every byte you could. So I was told a long time ago by a HP instructor on a Serviceguard course that MAX_CONFIGURED_PACKAGES controls the number of rows in some memory table which the Serviceguard daemon cmcld maintains. The larger the table, the more memory is consumed.

A quick test I did with MAX_CONFIGURED_PACKAGES set to 100 and then to 5 - the output of "UNIX95= ps -C cmcld -o comm,sz,vsz" :

MAX_CONFIGURED_PACKAGES=100:

COMMAND           SZ     VSZ

cmcld            5045 20180

MAX_CONFIGURED_PACKAGES=5:

COMMAND           SZ     VSZ

cmcld            3045 12180 

Of course in todays world, these sizes are not as significant (which is probably why MAX_CONFIGURED_PACKAGES defaults to 300 in recent versions of Serviceguard), but I guess the Serviceguard developers thought someone might still care, and left them in.

[Ralf Seefeldt]

Hi Duncan,

Thank you for this detailed answer.

Ralf.