On 27.3.2014 10:10, Tommaso Boccali wrote:
> ok, but what happens if a site restarts its cmsd when the redirector
> points just to one redirector (because the other is off)?
> when the second redirector comes back in the DNS list, will the site
> pick it up or not?
that's I don't know, just my wild guess is nothing bad would happened
from client side if you can keep up at least with one host from the
DNS-RR. Also that's why my concern whether "all" or "any" while using
"+" at the time.
If someone has tested proposed scenario by you would be great share the
knowledge.
Thanks,
Marian
> thanks!
>
> tom
>
>
> On Thu, Mar 27, 2014 at 4:08 PM, Marian Zvada <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
>
> Hi Tommaso,
>
> we have very same setup for CMS T2 and currently in commissioning
> process. We have DNS round-robin alias between FNAL and UNL and use
> the following in the config:
>
> all.manager meta all cmsxrootd.fnal.gov <http://cmsxrootd.fnal.gov>+
> 1213
> (xrootd1.fnal.gov <http://xrootd1.fnal.gov> and xrootd.unl.edu
> <http://xrootd.unl.edu> behind that)
>
> => I think this should be adapted also for your setup as well I
> believe, though pointing to different aliased host.
>
> For the question of "all" as parameter I was already asking in
> developers list what's beneficial, all || any, but didn't get
> response so far. Here it's documented but I didn't get full
> understanding what's recommended from operation point of view while
> using DNS-RR setup:
> http://xrootd.org/doc/prod/__cms_config.htm#_Toc339484334
> <http://xrootd.org/doc/prod/cms_config.htm#_Toc339484334>
>
> However, we stick so far with:
> all.manager meta all cmsxrootd.fnal.gov <http://cmsxrootd.fnal.gov>+
> 1213
>
> Also, currently each of top redirectors in the DNS-RR alias
> subscribes to global redirector:
> all.manager meta any cms-xrd-global.cern.ch
> <http://cms-xrd-global.cern.ch>+ 1098
> (see 'any' in this case)
>
> Hope that helps.
>
> -Marian
>
>
> On 27.3.2014 3:43, Tommaso Boccali wrote:
>
> Ciao, reading CMSD documentation I read
>
>
> 2.1 manager
>
> ...
>
> 8) If the manager host name ends with a plus, then all the IP
> addresses
> associated with host are treated as managers and every non-manager
> *cmsd* and *xrootd* subscribes to each one. This allows you to
> easily
>
> construct fault-tolerant configurations using the IP address alias
> feature in DNS.
>
>
>
> I would like to use this: we have a setup in which a regional
> redirector
> is replicated 2+ times, and all the redirectors are resolved via a
> single DNS name, which reports 2+ IPs.
> I understand cmsd upon start will connect to ALL of them, right?
>
> That said (supposing I understood correctly), I have a second
> question:
> the IPs returned via DNS queries are supposed to be changing
> with time,
> because we have automatic removal of those which are not ok at a
> given
> moment.
>
> What happens if a site starts cmsd when an IP is not present? If
> later
> that goes back in to the DNS, will it be picked up or the list of
> manager is built statically at startup?
>
> thanks a lot
>
> tom
>
> --
> Tommaso Boccali
> INFN Pisa
>
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>
> --
> Tommaso Boccali
> INFN Pisa
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