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+ 1213
(xrootd1.fnal.gov and 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

However, we stick so far with:
all.manager meta all 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+ 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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