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Bug 878662

Summary: PRD35 - [RFE] Mechanism for adding additional fence agents to mgr
Product: Red Hat Enterprise Virtualization Manager Reporter: Ian Pilcher <ipilcher>
Component: RFEsAssignee: Eli Mesika <emesika>
Status: CLOSED ERRATA QA Contact: sefi litmanovich <slitmano>
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: aberezin, bazulay, dfediuck, dsulliva, emesika, iheim, ipilcher, juwu, liko, lpeer, oourfali, pparsons, pstehlik, rbalakri, rhenness, sherold, ylavi
Target Milestone: ---Keywords: FutureFeature
Target Release: 3.5.0Flags: ylavi: needinfo? (ipilcher)
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: infra
Fixed In Version: ovirt-engine-3.5.0_beta Doc Type: Enhancement
Doc Text:
With this update, you can now set up custom fence agents for your Red Hat Enterprise Virtualization 3.5 environment. For more information, see https://access.redhat.com/articles/1238743.
Story Points: ---
Clone Of: Environment:
Last Closed: 2015-02-11 17:50:50 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: Infra RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1109796    
Bug Blocks: 1121487, 1142923, 1156165    

Description Ian Pilcher 2012-11-20 21:42:08 UTC
There are a number of situations in which it is desirable to add additional fence agents to the manager.  For example,

* Testing/demoing RHEV with nested KVM (fence-virsh)
* Testing RHEV on a new hardware type

Currently, adding a new agent requires modifying (at least) the VdsFenceType and VdsFenceOptionMapping configuration settings in the database, which is both ugly and risky.  It would be useful to have a "supported" method for adding additional fence agents.

"Supported" == we support the method of adding the agents, not that we support the additional agents themselves.

Comment 1 Itamar Heim 2012-11-20 21:47:16 UTC
maybe what we did for custom properties is relevant here?
we just added another config for user defined.
here it would be CustomVdsFenceType, CustomVdsFenceOptionMapping
and all code paths would be concatanating these with the builtin ones.

Comment 7 Dave Sullivan 2013-09-17 21:21:54 UTC
So did this get bumped off 3.3?

Customer was after something like...

vdsFenceType=script
vdsFenceOptionMapping=/pathtoscripttoexecute/serialfence

the serialfence script would then execute the reset

We wouldn't provide the script per se, just the mechanism to align to an customer abstract script.

The workaround is to see if we can do this by making direct changes into the database.

The long term BZ is to provide an interface via RHEVM gui to allow users to add in a specified fencing mechnism, in this case an ad-hoc script path

I'm going to be testing the "unsupported" workaround mentioned at the top this week but wanted to check on target release for this bz in rhev

Comment 9 Ryan Hennessy 2013-10-01 16:31:33 UTC
So the customer would be ok with maintaining the scripts on each of the hosts.   This would not be the ideal situation but, as I understand it, that would be the easiest way to provide the service without having to change the current RHEV fencing methodology.

Comment 13 Eli Mesika 2014-06-16 12:10:34 UTC
Examples of how that worked prior to 3.5 in 3.5 can be found here:

http://www.ovirt.org/Custom_Fencing

comments to the tester
---------------------------

1) Have 2 Hosts A & B in the cluster, A with PM configured 
2) lets say that A is using apc_snmp for example
3) Copy on B:/usr/sbin/fence_apc_snmp to /usr/sbin/fence_custom
4) Follow instructions on http://www.ovirt.org/Custom_Fencing#oVirt_3.5 to add "custom" as custom fencing agent
5) Restart engine
6) Edit host A and change it to use "custom" as fence agent 
7) Click the TEST button and see that it works

Comment 14 sefi litmanovich 2014-08-25 12:41:43 UTC
Verified with ovirt-engine-3.5.0-0.0.master.20140821064931.gitb794d66.el6.noarch according to TCMS plan 14443.

Comment 18 errata-xmlrpc 2015-02-11 17:50:50 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2015-0158.html