[Engine-devel] SSH Soft Fencing

[Yair Zaslavsky]

----- Original Message -----
> From: "Eli Mesika" <emesika at redhat.com>
> To: "Martin Perina" <mperina at redhat.com>
> Cc: engine-devel at ovirt.org, "Yair Zaslavsky" <yzaslavs at redhat.com>, "Barak Azulay" <bazulay at redhat.com>
> Sent: Thursday, June 27, 2013 3:48:39 PM
> Subject: Re: SSH Soft Fencing
> 
> 
> 
> ----- Original Message -----
> > From: "Martin Perina" <mperina at redhat.com>
> > To: engine-devel at ovirt.org
> > Cc: "Yair Zaslavsky" <yzaslavs at redhat.com>, "Barak Azulay"
> > <bazulay at redhat.com>, "Eli Mesika" <emesika at redhat.com>
> > Sent: Thursday, June 27, 2013 1:51:06 PM
> > Subject: SSH Soft Fencing
> > 
> > Hi,
> > 
> > SSH Soft Fencing is a new feature for 3.3 and it tries to restart VDSM
> > using SSH connection on non responsive hosts prior to real fencing.
> > More info can be found at
> > 
> > http://www.ovirt.org/Automatic_Fencing#Automatic_Fencing_in_oVirt_3.3
> > 
> > In current SSH Soft Fencing implementation the restart VDSM using SSH
> > command is part of standard fencing implementation in
> > VdsNotRespondingTreatmentCommand. But this command is executed only
> > if a host has a valid PM configuration. If host doesn't have a valid
> > PM configuration, the execution of the command is disabled and host
> > state is change to Non Responsive.
> > 
> > So my question are:
> > 
> > 1) Should SSH Soft Fencing be executed on hosts without valid PM
> >    configuration?
> 
> I think that the answer should be yes. The vdsm restart will solve most of
> problems , so why not using it whether a PM agent is defined or not.
I agree.
I would like to say that I also don't like the fact that VdsNotRespondingTreatment extends RestartVdsCommand.
One should ask if "non responding treatment is a restart vds operation" or maybe RestartVdsCommand is just a step in the non responding treatment (inheritance vs containment/delegation).
I think that VdsNotRespodingTreatment should delegate the call to RestartVdsCommand as the 2nd step after issuing the Soft Fencing command.
Thoughts anyone?

> 
> > 
> > 2) Should VDSM restart using SSH command be reimplemented
> >    as standalone command to be usable also in other parts of engine?
> >    If 1) is true, I think it will have to be done anyway.

I agree here. 
> 
> +1
> 
> > 
> > 
> > Martin Perina
> > 
>