Re: Director Failover
BMan <[email protected]>
| Newsgroups | gmane.linux.redhat.piranha |
|---|---|
| Message-ID | <[email protected]> |
It's most likely a kernel patch I mentioned earlier, not a piranha patch. The tcp/ip stack deals with arping. If memory serves me right, David Miller ([email protected]) is the guru behind the stack and of course Alan Cox ([email protected]) is the gatekeeper of kernel code. If you want to here it from the horses mouth then I'd ask one of these two gents if the patch has been incorporated into the newer revs of kernels. If it has been incorporated you may want to know from what kernel rev so you can compare it to yours. If it has not then you will have to custom build a kernel with the patch included. They may also be able to give you the down sides of applying this patch to the kernel. If it is not apart of the recent kernels then the question I would ask is why? In other words, what are the ramifications for adding it and/or the gotcha's. Last but not least you'll have to also maintain your custom kernel too. :/ Regards, BMan ong cheechye wrote: >Yes. Perhaps it's the arp issue that result in the >telnet connection to stay for a while. I have read in >the mailing list that some piranha patch is required >for the VIP takeover by backup director to happen. Is >that true ? (i.e. remove primary director eth alias >for VIP and add backup director eth alias for VIP >during director failover) > > --- BMan <[email protected]> wrote: > First >off, piranha is nothing more than a name given > > >>to the "Frontend" >>or gui. With that said, it utilizes the same ipvs >>tables as any other >>lvs Linux based solution. If the other list says it >>can be done, my >>guess is they are doing a lot more hard-core hand >>coding to handle >>arping issues that the Piranha interface can not >>accomplish unless >>they've done some major work on. My guess is they >>haven't sense Advance >>Server is the new "flag ship". Of course I have no >>idea of the context >>of which you speak of so bare with me as I try to go >>into a little more >>detail for you. >> >>The real key in making any lvs solution work is >>understanding how arp >>works. What happens to arp tables on the director >>and boxes providing >>services when fail over occures can be monitored to >>help diagnose. A >>sniffer, standard arp commands, netcat and a few >>other tools that >>escape my brain are good diagnostic tools. The key >>to seeing what the >>interfaces are seeing. In the Cisco world all of >>the arp issues are >>taken care of at the router/director level and boxes >>behind it are saved >>from the arp issues and storms that can happen. At >>one point the kernel >>team wasn't putting patches into the kernel to >>handle lvs, I'm not sure >>if it is back in or removed forever??\ >> >><Mike any time you want to jump in here feel free> >> >>There are ways of setting up a combination of lo >>interfaces along with >>iptables to handle some of these issues. It is very >>cluge though and >>hard to maintain in my opinion. I say lo interfaces >>because even dummy >>interfaces arp out. :/ I'm not sure where they are >>with integrating >>back into the mainstream kernel patches that handle >>some of this (Mike >>?). You may also want to look at doing that. I do >>know that Red Hat's >>Advanced Server handles a lot of these issues in a >>more comprehensible >>package. It also uses shared SCSI in a better >>manner than Piranha can. >> On the flip side there are a whole new set of issue >>with that solution >>that I don't want to get into. >> >>Bottom line here is it is almost impossible for me >>to diagnose your >>setup via email. What I can almost bet my life on >>is your most likely >>running into an arping issue that the plain "out of >>the box piranha" >>doesn't handle without minipulating the underlying >>parts that it sets on >>top off. >> >>Hope this sheads some light, good luck. >> >>Regards, >>BMan >> >> >> >>ong cheechye wrote: >> >> >> >>>Hi BMan, >>> >>>I've read about questions raised on connection >>>synchronization between the primary and backup >>>director in the lvs mailing list. I suppose that >>> >>> >>means >> >> >>>existing connection can be maintained during >>> >>> >>director >> >> >>>failover. Does that means connection >>> >>> >>synchronization >> >> >>>is achieved in other software but not Piranha ? >>> >>>During my test with piranha, I noticed the telnet >>>session is still on shortly after the director >>>failover but went dead eventually. How do you >>> >>> >>explain >> >> >>>this observation ? >>> >>>Thanks >>>Chee Chye >>> >>>--- BMan <[email protected]> wrote: > The >>>existing telnet connection will be disconnected >>> >>> >>> >>> >>>>because Piranha >>>>(regardless of routing method used) does not >>>> >>>> >>track >> >> >>>>session state. The >>>>same holds true for ssh, ftp and similar services. >>>> >>>>Regards, >>>>BMan >>>> >>>>ong cheechye wrote: >>>> >>>> >>>> >>>> >>>> >>>>>Hi, >>>>> >>>>>I'm testing Piranha+Direct routing with telnet >>>>> >>>>> >>>>> >>>>> >>>>service >>>> >>>> >>>> >>>> >>>>>using a primary director and a backup director >>>>> >>>>> >>>>> >>>>> >>>>which >>>> >>>> >>>> >>>> >>>>>is also acting as a realserver (due to shortage >>>>> >>>>> >>of >> >> >>>>>machines). >>>>> >>>>>I telnet from another machine to the VIP. I then >>>>> >>>>> >>>>> >>>>> >>>>stop >>>> >>>> >>>> >>>> >>>>>the pulse in the primary director and the backup >>>>>director take over. Would the existing telnet >>>>>connection be disconnected ? >>>>> >>>>>Thanks >>>>>Chee Chye >>>>> >>>>> >>>>> >>>>> >>>>__________________________________________________ >>>> >>>> >>>>>Do You Yahoo!? >>>>>Promote your business from just $5 a month! >>>>>http://sg.biztools.yahoo.com >>>>> >>>>> >>>>> >>>>>_______________________________________________ >>>>>Piranha-list mailing list >>>>>[email protected] >>>>> >>>>> >>>>> >>>>> >>>https://listman.redhat.com/mailman/listinfo/piranha-list >>> >>> >>>> >>>> >>>> >>>> >>>>> >>>>> >>>>> >>>>> >>>>_______________________________________________ >>>>Piranha-list mailing list >>>>[email protected] >>>> >>>> >>>> >>>> >>>> >>https://listman.redhat.com/mailman/listinfo/piranha-list >> >> >> >>>__________________________________________________ >>>Do You Yahoo!? >>>Promote your business from just $5 a month! >>>http://sg.biztools.yahoo.com >>> >>> >>> >>>_______________________________________________ >>>Piranha-list mailing list >>>[email protected] >>> >>> >>https://listman.redhat.com/mailman/listinfo/piranha-list >> >> >>> >>> >>> >>> >> >> >> > >__________________________________________________ >Do You Yahoo!? >Promote your business from just $5 a month! >http://sg.biztools.yahoo.com > > > >_______________________________________________ >Piranha-list mailing list >[email protected] >https://listman.redhat.com/mailman/listinfo/piranha-list > > >