<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 4 Apr 2017, at 12:21, Roy Golan <<a href="mailto:rgolan@redhat.com" class="">rgolan@redhat.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><br class=""><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Tue, Apr 4, 2017 at 1:16 PM Michal Skrivanek <<a href="mailto:michal.skrivanek@redhat.com" class="">michal.skrivanek@redhat.com</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg">On 4 Apr 2017, at 12:10, Roy Golan <<a href="mailto:rgolan@redhat.com" class="gmail_msg" target="_blank">rgolan@redhat.com</a>> wrote:</div><br class="m_-4059592897398397391Apple-interchange-newline gmail_msg"><div class="gmail_msg"><div dir="ltr" class="gmail_msg"><br class="gmail_msg"><br class="gmail_msg"><div class="gmail_quote gmail_msg"><div dir="ltr" class="gmail_msg">On Tue, Apr 4, 2017 at 12:49 PM Yaniv Kaul <<a href="mailto:ykaul@redhat.com" class="gmail_msg" target="_blank">ykaul@redhat.com</a>> wrote:<br class="gmail_msg"></div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg">On Tue, Apr 4, 2017 at 12:29 PM, Roy Golan <span dir="ltr" class="gmail_msg"><<a href="mailto:rgolan@redhat.com" class="gmail_msg" target="_blank">rgolan@redhat.com</a>></span> wrote:<br class="gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_msg">I'm working on a POC lately on a change to stats collection and retrieval by VDSM. The moto is to cut all we can from host/vm stats (possibly caps) and report only core-business stuff to the engine. Engine will retrieve the rest through a 3rd party provider</div></div></blockquote></div></div></div></blockquote></div></div></div></blockquote><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div dir="ltr" class="gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_msg">(nevermind what is it atm)<br class="gmail_msg"></div></div></blockquote></div></div></div></blockquote></div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg">I hope it’s the same one as for VM stats, collectd:)</div></div></blockquote><div class=""><br class="">Intended for this as well. <br class=""></div></div></div></div></blockquote><div><br class=""></div>great!</div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div dir="ltr" class="gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Being backward compatible by design, I have to support 2 API versions for Host.getStats , '4.1' and '4.2'.<br class="gmail_msg"></div><div class="gmail_msg">Except from supplying less parameters, I want VDSM to do less stuff. It doesn't need to sample what it doesn't report. In other words I want '4.1-sampling' and '4.2-sampling'<br class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"># Introducing 'configuration' Verb:<br class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">As engine knows always(Hosted Engine as well) what cluster version this host belongs to, it can configure VDSM to operate in cluster version mode.<br class="gmail_msg"></div></div></blockquote></div></div></div></blockquote></div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg">why not running it in parallel for one version?</div><div class="gmail_msg"></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div></div></blockquote><div class="">What is the benefit? <br class=""></div></div></div></div></blockquote><div><br class=""></div>just so you do not need any configuration verb nor persistence, not much else.</div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div dir="ltr" class="gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"> Host.configure(config={version: 4.2}<br class="gmail_msg"></div><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Consider this verb, pre-activating using 'Host.getCaps' to set the context.<br class="gmail_msg">It will set the righjt sampling method, and other stuff if needed then API endpoints will have the right permutation of the api to answer it.<br class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">4.2 host can operate in 4.1 mode:<br class="gmail_msg"> Host.configure(config={version: 4.1}<br class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Issue: moving a 4.2 host from 4.2 cluster to 4.1 is a problem since engine needs to know this is a new vdsm that has the verb available. One way to overcome that is to fire the verb for every host regardless of the version and disregard an error that implies the verb doesn't exist.<br class="gmail_msg"></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div></div></div></div><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg">Isn't it solved by host re-installation?</div></div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">We allow maintenance + change host cluster so not always. Was this changed? <br class="gmail_msg"></div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"># Engine:<br class="gmail_msg"></div><div class="gmail_msg">Engine will have a handling of the verb per version.<br class="gmail_msg"></div><div class="gmail_msg">Host/Vms monitoring should be changed - I suggest to move out of the monitoring code the whole stats collection as it is a different task which is orthogonal to 'monitoring' and in 4.2 more than before.<br class="gmail_msg"><br class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">I know configuration for VDSM has been discussed before and there are probably tons of ways to do it. When you share your thoughts please remember that configuration is a by-product of the effort.<br class="gmail_msg"></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div></div></div></div><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg">How do we persist this level on VDSM? Or we don't, and if VDSM is restarted it is again back to 4.1 mode until Engine tells it otherwise?</div></div></div></div></blockquote></div></div></div></blockquote><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div dir="ltr" class="gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg">Y.</div></div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Must persist it somehow otherwise there is a race when the engine will send send a stats request and will get the wrong answer. I'm wondering if using differnt endpoints is the right solution here to prevent that from happening. <br class="gmail_msg"></div><div class="gmail_msg"> method: Host.getStats version: 4.1 <br class="gmail_msg"></div></div></div></div></blockquote><div class="gmail_msg"><br class="gmail_msg"></div></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg">would it be a problem? assuming that the code is easily started/stopped within vdsm, we can just change the behavior based on receiving one or the other verb for the first time after vdsm starts</div></div></blockquote><div class=""><br class=""></div><div class="">But we should prefer a deliberate action. Doing that as a side effect is surprising for an API verb. What would happen in case you invoke 'vdsm-client’ ?<br class=""></div></div></div></div></blockquote><div><br class=""></div>I do not mean to switch for any client, more like a single “upgrade” of communication once the new verb is called. So once the engine calls the new verb the legacy stats thread is stopped and vdsClient <oldVerb> stops returning meaningful data.</div><div>Actually, moving host back to older cluster doesn’t really need switching back either - you still have the new engine capable of handling the new verb despite older cluster.</div><div><br class=""></div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><div class="gmail_quote"><div class=""> <br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Thanks,</div><div class="gmail_msg">michal</div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><div dir="ltr" class="gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg"> <br class="gmail_msg"></div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg"> </div><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"></blockquote></div></div></div><div dir="ltr" class="gmail_msg"><div class="gmail_extra gmail_msg"><div class="gmail_quote gmail_msg"><blockquote class="gmail_quote gmail_msg" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="gmail_msg"><div class="gmail_msg">Nevertheless it can be potentially beneficial to more functions in vdsm.<br class="gmail_msg"></div><div class="gmail_msg"><br class="gmail_msg"></div><div class="gmail_msg">Thanks,<br class="gmail_msg"></div><div class="gmail_msg">Roy<br class="gmail_msg"></div><div class="gmail_msg"><br class="gmail_msg"></div></div>
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