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On 4 Apr 2017, at 12:21, Roy Golan <rgolan@redhat.com> wrote: =20 =20 =20 On Tue, Apr 4, 2017 at 1:16 PM Michal Skrivanek = <michal.skrivanek@redhat.com <mailto:michal.skrivanek@redhat.com>> = wrote:
On 4 Apr 2017, at 12:10, Roy Golan <rgolan@redhat.com = <mailto:rgolan@redhat.com>> wrote: =20 =20 =20 On Tue, Apr 4, 2017 at 12:49 PM Yaniv Kaul <ykaul@redhat.com = <mailto:ykaul@redhat.com>> wrote: On Tue, Apr 4, 2017 at 12:29 PM, Roy Golan <rgolan@redhat.com = <mailto:rgolan@redhat.com>> wrote: 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 (nevermind what is it atm) =20 I hope it=E2=80=99s the same one as for VM stats, collectd:) =20 Intended for this as well.=20
=20
=20 Being backward compatible by design, I have to support 2 API versions = for Host.getStats , '4.1' and '4.2'. 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' =20 # Introducing 'configuration' Verb: =20 As engine knows always(Hosted Engine as well) what cluster version =
great! this host belongs to, it can configure VDSM to operate in cluster = version mode.
=20 why not running it in parallel for one version? =20 What is the benefit? =20
=20 Host.configure(config=3D{version: 4.2} =20 Consider this verb, pre-activating using 'Host.getCaps' to set the = context. It will set the righjt sampling method, and other stuff if needed =
=20 4.2 host can operate in 4.1 mode: Host.configure(config=3D{version: 4.1} =20 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 =
=20 Isn't it solved by host re-installation? =20 We allow maintenance + change host cluster so not always. Was this = changed?=20 =20 =20 # Engine: Engine will have a handling of the verb per version. 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. =20 =20 I know configuration for VDSM has been discussed before and there are =
=20 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? Y. =20 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 =
just so you do not need any configuration verb nor persistence, not much = else. then API endpoints will have the right permutation of the api to answer = it. the version and disregard an error that implies the verb doesn't exist. probably tons of ways to do it. When you share your thoughts please = remember that configuration is a by-product of the effort. prevent that from happening.=20
method: Host.getStats version: 4.1=20 =20 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 =20 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=E2=80=99 ?
I do not mean to switch for any client, more like a single =E2=80=9Cupgrad= e=E2=80=9D 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. Actually, moving host back to older cluster doesn=E2=80=99t really need = switching back either - you still have the new engine capable of = handling the new verb despite older cluster.
=20 =20 Thanks, michal =20
=20 =20 =20 Nevertheless it can be potentially beneficial to more functions in =
vdsm.
=20 Thanks, Roy =20 =20 _______________________________________________ Devel mailing list Devel@ovirt.org <mailto:Devel@ovirt.org> http://lists.ovirt.org/mailman/listinfo/devel = <http://lists.ovirt.org/mailman/listinfo/devel> =20 _______________________________________________ Devel mailing list Devel@ovirt.org <mailto:Devel@ovirt.org> http://lists.ovirt.org/mailman/listinfo/devel = <http://lists.ovirt.org/mailman/listinfo/devel>
--Apple-Mail=_4D0244E4-4D4A-48DB-B16B-BE856667DA7B Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 <html><head><meta http-equiv=3D"Content-Type" content=3D"text/html = charset=3Dutf-8"></head><body style=3D"word-wrap: break-word; = -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" = class=3D""><br class=3D""><div><blockquote type=3D"cite" class=3D""><div = class=3D"">On 4 Apr 2017, at 12:21, Roy Golan <<a = href=3D"mailto:rgolan@redhat.com" class=3D"">rgolan@redhat.com</a>> = wrote:</div><br class=3D"Apple-interchange-newline"><div class=3D""><div = dir=3D"ltr" class=3D""><br class=3D""><br class=3D""><div = class=3D"gmail_quote"><div dir=3D"ltr" class=3D"">On Tue, Apr 4, 2017 at = 1:16 PM Michal Skrivanek <<a = href=3D"mailto:michal.skrivanek@redhat.com" = class=3D"">michal.skrivanek@redhat.com</a>> wrote:<br = class=3D""></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 = .8ex;border-left:1px #ccc solid;padding-left:1ex"><div = style=3D"word-wrap:break-word" class=3D"gmail_msg"><div = class=3D"gmail_msg"><blockquote type=3D"cite" class=3D"gmail_msg"><div = class=3D"gmail_msg">On 4 Apr 2017, at 12:10, Roy Golan <<a = href=3D"mailto:rgolan@redhat.com" class=3D"gmail_msg" = target=3D"_blank">rgolan@redhat.com</a>> wrote:</div><br = class=3D"m_-4059592897398397391Apple-interchange-newline gmail_msg"><div = class=3D"gmail_msg"><div dir=3D"ltr" class=3D"gmail_msg"><br = class=3D"gmail_msg"><br class=3D"gmail_msg"><div class=3D"gmail_quote = gmail_msg"><div dir=3D"ltr" class=3D"gmail_msg">On Tue, Apr 4, 2017 at = 12:49 PM Yaniv Kaul <<a href=3D"mailto:ykaul@redhat.com" = class=3D"gmail_msg" target=3D"_blank">ykaul@redhat.com</a>> wrote:<br = class=3D"gmail_msg"></div><blockquote class=3D"gmail_quote gmail_msg" = style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_extra gmail_msg"><div class=3D"gmail_quote gmail_msg">On = Tue, Apr 4, 2017 at 12:29 PM, Roy Golan <span dir=3D"ltr" = class=3D"gmail_msg"><<a href=3D"mailto:rgolan@redhat.com" = class=3D"gmail_msg" target=3D"_blank">rgolan@redhat.com</a>></span> = wrote:<br class=3D"gmail_msg"><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"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></di= v></div></blockquote><blockquote type=3D"cite" class=3D"gmail_msg"><div = class=3D"gmail_msg"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_quote gmail_msg"><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_extra gmail_msg"><div class=3D"gmail_quote = gmail_msg"><blockquote class=3D"gmail_quote gmail_msg" style=3D"margin:0 = 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_msg">(nevermind what is it = atm)<br = class=3D"gmail_msg"></div></div></blockquote></div></div></div></blockquot= e></div></div></div></blockquote><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div></div></div><div style=3D"word-wrap:break-word" = class=3D"gmail_msg"><div class=3D"gmail_msg">I hope it=E2=80=99s the = same one as for VM stats, collectd:)</div></div></blockquote><div = class=3D""><br class=3D"">Intended for this as well. <br = class=3D""></div></div></div></div></blockquote><div><br = class=3D""></div>great!</div><div><br class=3D""><blockquote type=3D"cite"= class=3D""><div class=3D""><div dir=3D"ltr" class=3D""><div = class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0 = 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div = style=3D"word-wrap:break-word" class=3D"gmail_msg"><div = class=3D"gmail_msg"></div></div><div style=3D"word-wrap:break-word" = class=3D"gmail_msg"><div class=3D"gmail_msg"><br = class=3D"gmail_msg"><blockquote type=3D"cite" class=3D"gmail_msg"><div = class=3D"gmail_msg"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_quote gmail_msg"><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_extra gmail_msg"><div class=3D"gmail_quote = gmail_msg"><blockquote class=3D"gmail_quote gmail_msg" style=3D"margin:0 = 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div><div class=3D"gmail_msg">Being backward = compatible by design, I have to support 2 API versions for Host.getStats = , '4.1' and '4.2'.<br class=3D"gmail_msg"></div><div = class=3D"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=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"gmail_msg"># Introducing 'configuration' Verb:<br = class=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"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=3D"gmail_msg"></div></div></blockquote></div></div></div></blockquot= e></div></div></div></blockquote><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div></div></div><div style=3D"word-wrap:break-word" = class=3D"gmail_msg"><div class=3D"gmail_msg">why not running it in = parallel for one version?</div><div class=3D"gmail_msg"></div></div><div = style=3D"word-wrap:break-word" class=3D"gmail_msg"><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div></div></blockquote><div = class=3D"">What is the benefit? <br = class=3D""></div></div></div></div></blockquote><div><br = class=3D""></div>just so you do not need any configuration verb nor = persistence, not much else.</div><div><br class=3D""><blockquote = type=3D"cite" class=3D""><div class=3D""><div dir=3D"ltr" class=3D""><div = class=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0 = 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div = style=3D"word-wrap:break-word" class=3D"gmail_msg"><div = class=3D"gmail_msg"><blockquote type=3D"cite" class=3D"gmail_msg"><div = class=3D"gmail_msg"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_quote gmail_msg"><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_extra gmail_msg"><div class=3D"gmail_quote = gmail_msg"><blockquote class=3D"gmail_quote gmail_msg" style=3D"margin:0 = 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_msg"><br = class=3D"gmail_msg"> Host.configure(config=3D{version: 4.2}<br = class=3D"gmail_msg"></div><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div><div class=3D"gmail_msg">Consider this verb, = pre-activating using 'Host.getCaps' to set the context.<br = class=3D"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=3D"gmail_msg"><br = class=3D"gmail_msg"></div><div class=3D"gmail_msg">4.2 host can operate = in 4.1 mode:<br class=3D"gmail_msg"> = Host.configure(config=3D{version: 4.1}<br class=3D"gmail_msg"><br = class=3D"gmail_msg"></div><div class=3D"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=3D"gmail_msg"></div></div></blockquote><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div></div></div></div><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_extra gmail_msg"><div = class=3D"gmail_quote gmail_msg"><div class=3D"gmail_msg">Isn't it solved = by host re-installation?</div></div></div></div></blockquote><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"gmail_msg">We allow maintenance + change host cluster so = not always. Was this changed? <br class=3D"gmail_msg"></div><blockquote = class=3D"gmail_quote gmail_msg" style=3D"margin:0 0 0 = .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_extra gmail_msg"><div = class=3D"gmail_quote gmail_msg"><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div><blockquote class=3D"gmail_quote gmail_msg" = style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"gmail_msg"># Engine:<br class=3D"gmail_msg"></div><div = class=3D"gmail_msg">Engine will have a handling of the verb per = version.<br class=3D"gmail_msg"></div><div class=3D"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=3D"gmail_msg"><br class=3D"gmail_msg"><br = class=3D"gmail_msg"></div><div class=3D"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=3D"gmail_msg"></div></div></blockquote><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div></div></div></div><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_extra gmail_msg"><div = class=3D"gmail_quote gmail_msg"><div class=3D"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></blockqu= ote><blockquote type=3D"cite" class=3D"gmail_msg"><div = class=3D"gmail_msg"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_quote gmail_msg"><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_extra gmail_msg"><div class=3D"gmail_quote = gmail_msg"><div = class=3D"gmail_msg">Y.</div></div></div></div></blockquote><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"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=3D"gmail_msg"></div><div class=3D"gmail_msg"> method: = Host.getStats version: 4.1 <br = class=3D"gmail_msg"></div></div></div></div></blockquote><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div></div></div><div = style=3D"word-wrap:break-word" class=3D"gmail_msg"><div = class=3D"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=3D""><br class=3D""></div><div = class=3D"">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=E2=80=99 ?<br = class=3D""></div></div></div></div></blockquote><div><br = class=3D""></div>I do not mean to switch for any client, more like a = single =E2=80=9Cupgrade=E2=80=9D 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=E2=80=99= 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=3D""></div><div><br class=3D""><blockquote type=3D"cite" = class=3D""><div class=3D""><div dir=3D"ltr" class=3D""><div = class=3D"gmail_quote"><div class=3D""> <br = class=3D""></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 = .8ex;border-left:1px #ccc solid;padding-left:1ex"><div = style=3D"word-wrap:break-word" class=3D"gmail_msg"><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"gmail_msg">Thanks,</div><div = class=3D"gmail_msg">michal</div></div><div style=3D"word-wrap:break-word" = class=3D"gmail_msg"><div class=3D"gmail_msg"><br = class=3D"gmail_msg"></div><div class=3D"gmail_msg"><blockquote = type=3D"cite" class=3D"gmail_msg"><div class=3D"gmail_msg"><div = dir=3D"ltr" class=3D"gmail_msg"><div class=3D"gmail_quote = gmail_msg"><div class=3D"gmail_msg"> <br = class=3D"gmail_msg"></div><blockquote class=3D"gmail_quote gmail_msg" = style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_extra gmail_msg"><div class=3D"gmail_quote = gmail_msg"><div class=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"gmail_msg"> </div><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"></blockquote></div></div></div><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_extra gmail_msg"><div = class=3D"gmail_quote gmail_msg"><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex"><div dir=3D"ltr" class=3D"gmail_msg"><div = class=3D"gmail_msg">Nevertheless it can be potentially beneficial to = more functions in vdsm.<br class=3D"gmail_msg"></div><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div><div = class=3D"gmail_msg">Thanks,<br class=3D"gmail_msg"></div><div = class=3D"gmail_msg">Roy<br class=3D"gmail_msg"></div><div = class=3D"gmail_msg"><br class=3D"gmail_msg"></div></div> <br class=3D"gmail_msg"></blockquote></div></div></div><div dir=3D"ltr" = class=3D"gmail_msg"><div class=3D"gmail_extra gmail_msg"><div = class=3D"gmail_quote gmail_msg"><blockquote class=3D"gmail_quote = gmail_msg" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc = solid;padding-left:1ex">_______________________________________________<br= class=3D"gmail_msg"> Devel mailing list<br class=3D"gmail_msg"> <a href=3D"mailto:Devel@ovirt.org" class=3D"gmail_msg" = target=3D"_blank">Devel@ovirt.org</a><br class=3D"gmail_msg"> <a href=3D"http://lists.ovirt.org/mailman/listinfo/devel" = rel=3D"noreferrer" class=3D"gmail_msg" = target=3D"_blank">http://lists.ovirt.org/mailman/listinfo/devel</a><br = class=3D"gmail_msg"></blockquote></div><br = class=3D"gmail_msg"></div></div> </blockquote></div></div> _______________________________________________<br = class=3D"gmail_msg">Devel mailing list<br class=3D"gmail_msg"><a = href=3D"mailto:Devel@ovirt.org" class=3D"gmail_msg" = target=3D"_blank">Devel@ovirt.org</a><br class=3D"gmail_msg"><a = href=3D"http://lists.ovirt.org/mailman/listinfo/devel" class=3D"gmail_msg"= = target=3D"_blank">http://lists.ovirt.org/mailman/listinfo/devel</a></div><= /blockquote></div><br class=3D"gmail_msg"></div></blockquote></div></div> </div></blockquote></div><br class=3D""></body></html>= --Apple-Mail=_4D0244E4-4D4A-48DB-B16B-BE856667DA7B--