topic Re: How to change default shadow set policy in Operating System - OpenVMS

How to change default shadow set policy

Toine_1 — Sun, 02 Aug 2009 12:11:03 GMT

Hello,

I have removed a node (NODE3) from a VMS cluster and joined a new node (NODE5) in the cluster. (VMS 8.3)
Now I want to change the default shadowset policy.

$ set shadow/policy=hbmm=(master_list=(NODE1,NODE2,NODE3,NODE4),count=3, reset_threshold=500000)/name=default

$ set shadow/policy=hbmm=(master_list=(NODE1,NODE2,NODE3,NODE5),count=3, reset_threshold=500000)/name=default

How can I active this default policy on existing shadowsets without a complete cluster shutdown?

/Toine

Re: How to change default shadow set policy

Wim Van den Wyngaert — Sun, 02 Aug 2009 13:27:46 GMT

Or you re-mount the disks or you apply the command to each shadow set (by hand).

Wim

Re: How to change default shadow set policy

Robert Brooks_1 — Sun, 02 Aug 2009 15:18:30 GMT

You have posed two questions, and answered the first one already.

Your examples are the way to change the default policy.

As you have discovered, however, changing the default policy does not change the policy of any shadow sets with HBMM in force. There is no way for HBMM to "know" the origin of a policy; all HBMM knows is that a shadow set has a policy with specific attributes, either from a "named" policy (and the default policy is just a "special" named policy), or a device-specific policy.

To see the way HBMM "stores" policies, use the command $ SHOW LOGICAL /TABLE=HBMM$*

As you can see, clusterwide logicals are the mechanism used to "store" policy information.

One cannot change the MASTER_LIST attribute of an HBMM policy that's enabled; you can only change the RESET_THRESHOLD (and even then, there are rules that apply to how that can happen).

That said, the way to "change" an HBMM policy for a given shadow set is to disable that policy and reenable a different policy.

Judicious use of F$DEVICE should make this a simple exercise, if the goal is to apply the same policy to every shadow set on a system (or cluster).

-- Rob

Re: How to change default shadow set policy

Toine_1 — Sun, 02 Aug 2009 18:15:52 GMT

I disabled hbmm on each shadowset and enabled it again with the two commands below. And it worked.

$
$ set shadow dsa1850/disable=hbmm
$ set shadow dsa1850/policy=hbmm=default
$

Thank you Rob and Wim for your advise.

/Toine