* Doron Fediuck <[email protected]> [2012-11-26 09:20]: > ----- Original Message ----- > > From: "Ryan Harper" <[email protected]> > > To: "Doron Fediuck" <[email protected]> > > Cc: "Sheldon" <[email protected]>, [email protected], "Zheng Sheng ZS > > Zhou" <[email protected]>, "Itamar > > Heim" <[email protected]>, [email protected], "Shu Ming" > > <[email protected]>, "Mark Wu" > > <[email protected]>, [email protected], [email protected], > > [email protected] > > Sent: Monday, November 26, 2012 4:01:48 PM > > Subject: Re: [vdsm] Review Request: Add an option to create a watchdog > > device. > > > > * Doron Fediuck <[email protected]> [2012-11-22 03:56]: > > > > > > ----- Original Message ----- > > > > > > > From: "Sheldon" <[email protected]> > > > > To: "Doron Fediuck" <[email protected]> > > > > Cc: [email protected], "Zheng Sheng ZS Zhou" <[email protected]>, > > > > "Itamar Heim" <[email protected]>, [email protected], "Shu > > > > Ming" > > > > <[email protected]>, "Mark Wu" > > > > <[email protected]>, > > > > [email protected], [email protected], [email protected] > > > > Sent: Thursday, November 22, 2012 11:00:18 AM > > > > Subject: Re: [vdsm] Review Request: Add an option to create a > > > > watchdog device. > > > > > > > On 11/21/2012 04:00 PM, Doron Fediuck wrote: > > > > > > > > > Currently, we do not have any plans to implement the engine > > > > > > side > > > > > > of > > > > > > the feature. > > > > > > > > > > > > > > > But I will add a watchdog feature page to describe how engine > > > > > > enable > > > > > > this feature. It's definitely great if any engine guy would > > > > > > like > > > > > > to > > > > > > take the engine part. I will be glad to provide help if > > > > > > needed. > > > > > > > > > > > > > > Hi Sheldon, > > > > > > > > > Any news on the engine side? > > > > > > > > > Currently the vdsm side is merged, while the engine side still > > > > > missing. > > > > > > > > > The wiki page also lacks the engine side. Can you please handle > > > > > it? > > > > > > > > > > > Hi Doron, > > > > > > > I have updated the wiki page. > > > > http://wiki.ovirt.org/wiki/Add_an_option_to_create_a_watchdog_device > > > > And for vdsm side, I should also add a new patch to report the > > > > watchdog event. > > > > > > > I can add a flat to vm's status, so engine can poll vm's status > > > > to > > > > check the event then notify the user, and let the user to take > > > > some > > > > actions, such as restart or dump guest for analysis. > > > > Perhaps event report channel is more better, but I have not find > > > > any > > > > in vdsm. But it is a big work to add an event register mechanism > > > > for > > > > vdsm. > > > > > > > what's your suggestion? > > > > > > > -- > > > > Sheldon Feng(?????????) <[email protected]> IBM Linux > > > > Technology > > > > Center > > > > > > Hi Sheldon, > > > AFAIK, watchdog fires automatically, so no real need for user > > > interaction > > > when an event happens. So I'd expect the user to set the relevant > > > action > > > before starting the VM. Once the watchdog is triggered, it will do > > > whatever > > > action he has set, and notify the user. > > > > > > So I'd expect the user to have a list of actions for the watchdog > > > device > > > in the engine UI, with a default of none. The user should be able > > > to choose > > > which action to set when starting or editing the VM (for next run). > > > > I'd like to suggest we pick something other than none by default > > since > > we've gone through the trouble of configuring and enabling a > > watchdog. > > I think it's worth the discussion of what a better default behavior > > should be given access to a watchdog. > > > > I'd suggest that a simple reboot mode would be most useful. > > > > Hi Ryan, good point. > The reason I asked for none is exactly since someone though of it > when writing the device actions. ie- otherwise no-op makes no sense, > but as we all know no-op sometimes proves to be a much needed option > if not the default one. > In this context, a watchdog has quite an explosive potential for a VM. > So for the sake of all users I'd rather ask them to specify exactly > what should be done. Otherwise- Primum non nocere. I'm sure one day > someone will appreciate it.
While I understand what your saying; I think it's worth actually walking through all of the actions and selecting the best here. VDSM has a role to play here in how *best* to configure a VM. I think that a watchdog can elevate the usefulness of a VM by ensuring that it stays running without user intervention. As you say, having an unexpected reboot when it's not wanted can cause an issue, so we have at least two areas to discuss: 1) watchdog fidelity; does it do what it's supposed to do at the right time and not malfunction. This requires testing and use to validate. Leaving the watchdog off by default will certainly reduce the amount of testing time. 2) watchdog configuration. What's the most reasonable and helpful configuration, this includes the action as well as any variables associated with that specific action. I think the best course here is to propose an initial configuration and start getting some test-time under the configuration for validation. If we're unwilling to enable an action by default, I'd like to have a discussion around why that's the case. The initial objection to always-on with action=reboot seems to be concern about the watchdog misfiring when it shouldn't. Are their other concerns? Another thought here is to think about the target guest OS type. It may be the case that specific actions/configurations make sense for one OS, but not the other[1] There was an engine-devel thread about libosinfo integration[2]. 1. http://rwmj.wordpress.com/2010/03/03/what-is-a-watchdog/#comment-4959 2. http://lists.ovirt.org/pipermail/engine-devel/2012-September/002544.html -- Ryan Harper Software Engineer; Linux Technology Center IBM Corp., Austin, Tx [email protected] _______________________________________________ Arch mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/arch
