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Issue migrated (2015-06-05) from old issue tracker http://mirrorbrain.org/issues/issue152

Title    Improve warning when mirror resolves to multiple IP adresses
 Priority   wish               Status         in-progress
Superseder                    Nosy List       mk, poeml
Assigned To poeml             Keywords

msg551 (view) Author: mk Date: 2014-02-25.14:19:46

Hello.

We're running a mirror site with several frontend servers connected to a shared
backend storage pool. We have noticed that projects that uses Mirrorbrain often
add our frontends individually despite our instructions to only add the shared
hostname and let our DNS handle the load balancing.

From what we can tell the issue is that users get this error message (from
mb/mb/asn.py):

warning: %r resolves to multiple IP addresses:
...
see http://mirrorbrain.org/archive/mirrorbrain/0042.html why this could
could be a problem, and what to do about it.

From the amount of projects we've seen doing this it's our understanding that a
lot of users don't read the page linked to in the warning; where it actually
says that this isn't a problem if the site uses shared storage like we do.

I would suggest that the warning is amended to include a note that the warning
is not necessarily a problem, something like the following:

warning: %r resolves to multiple IP addresses:
...
see http://mirrorbrain.org/archive/mirrorbrain/0042.html why this could
could be a problem, and what to do about it. Note that this is not
necessarily a problem and could actually be intended depending on the
mirror's configuration.

Marcus

msg552 (view) Author: poeml Date: 2014-02-26.21:28:49

Hi Marcus,

thanks for taking the time to write up your input here. I remember your mirror well from when
I maintained several mirrorbrain instances in the past. (Well, I can't remember details, since
it has been a long time.) The problem with some DNSrr'ed mirrors was that there were often
problems with them not being in sync. I'm not referring to your servers with that -- speaking
in general -- and actually it was not often the case. However, when such problems occured,
they were very hard to debug and find in the first place, which is why I got cautious when
noticing DNSrr setups. I concluded that it made sense to address the mirrors individually,
although I think that this should always be done in agreement with the mirror operators.
Mostly, the setups were quite static and didn't change over years, so it seemed like a
practical compromise in the cases where it was needed. Unfortunately, some mirror setups
didn't have admins that I could reach in any way, so sometimes there was no way to agree over
one or other way of handling the situation.

The warning now reads like this (r8484 and r8485 in trunk):

% mb/mb.py update --all nluug

warning: 'ftp.nluug.nl' resolves to multiple IP addresses: 192.87.102.42, 192.87.102.43
2001:610:1:80aa:192:87:102:42, 2001:610:1:80aa:192:87:102:43
see http://mirrorbrain.org/archive/mirrorbrain/0042.html why this could
could be a problem, and what to do about it. But note that this is not
necessarily a problem and could actually be intended depending on the
mirror's configuration (see http://mirrorbrain.org/issues/issue152).
It's best to talk to the admins.

If you have any other suggestions, they are welcome!

History
         Date          User   Action             Args
2014-05-01 15:07:29 karltom set    files: - index.html
2014-05-01 15:07:12 karltom set    files: + index.html
2014-02-26 21:29:20 poeml   set    assignedto: poeml
                                     status: unread -> in-progress
2014-02-26 21:28:49 poeml   set    nosy: + poeml
                                     messages: + msg552
2014-02-25 14:19:47 mk      create

(end of migrated issue)