LISTSERV 16.5 - XROOTD-L Archives

ciao andrew, understood & it makes sense, thanks.

But then. I need a different solution for stageout.

As you explained to me here,

all.manager meta all xrootd.infn.it+ 1213 (probably wrong since gmail is playing with the text, but nevermind ... it is what you wrote ;)

needs xrootd.infn.it to be the list of all possible redirectors, regardless of their state. Fine.

On the other hand, for CMSSW fallback I need to specify something like

if file /store/file.root not locally available --> try root://xrootd.infn.it//store/file.root

in this case, instead, I want xrootd.infn.it to resolve only to those redirectors which are _currently_ ok, right?

then I am afraid I need 2 DNS aliases

- xrootd-fulllist.infn.it : the machines which are installed as redirector, from which nagios never removes anything

- xrootd.infn.it : the subset of the previous with only currently working redirectors, to be used in the fallback statement.

Is this correct?

thanks again!

tom

On Fri, Mar 28, 2014 at 8:41 PM, Andrew Hanushevsky <[log in to unmask]> wrote:

Hi Tommaso,

See below...

On Fri, 28 Mar 2014, Tommaso Boccali wrote:

Let's say we prepare 2 regional redirectors, 1.1.1.1 and 2.2.2.2, and we
punt them in the DNS as xrootd.infn.it (no round robin: "host xrootd.infn.it"
will return 2 IP addresses).
Since we want to use xrootd.infn.it as fallback, we plan to have a nagios
test which checks 1.1.1.1 and 2.2.2.2 periodically, and in case one is NOT
ok, it is removed from the DNS.

You shuld never remove anuthing from DNS, it will break all the recoverability aspects of xrootd. Even if it's broken it should remian in DNS. Hence, you don't need anything special. Just leave both servers in DNS all teh time.

> So, question was:

let's say that site ABCD needs to restart the xrootd local servers, which
are configured as

all.manager meta all *xrootd.infn.it <http://xrootd.infn.it>*+ 1213

Uhm, tyhe above won't work/ Perhaps you really wanted to say

all.manager meta all xrootd.infn.it+ 1213

what happens if AT THE RESTART MOMENT xrootd.infn.it only resolves to
1.1.1.1 (since eventually 2.2.2.2 is broken)? And even more, what if 2
hours later 2.2.2.2 enters again the DNS resolution for

It won't re-resolve. That's why you always leave both addresses in DNS.

Andy

--
Tommaso Boccali
INFN Pisa