[CentOS-mirror] CentOS mirror

David Richardson David.Richardson at utah.edu
Mon Nov 12 21:05:50 UTC 2018


Thanks for the tip about repo length! I had not considered providing the packages from a second repo, only repointing the base repo.

DR

--
David Richardson <david.richardson at utah.edu<mailto:david.richardson at utah.edu>>
Center for High Performance Computing
University of Utah

On Nov 12, 2018, at 2:47 PM, Anssi Johansson <avij at centosproject.org<mailto:avij at centosproject.org>> wrote:

The chances for your mirror to be included in the 10 randomly picked mirrors is around 10/11 (91%) which does not sound that bad to me. The fastestmirror yum plugin should then theoretically be able to pick your mirror from that list of 10 mirrors, but if it fails, you will end up using some other mirror from Illinois. The fastestmirror plugin is suitable for determining if a mirror is in the same country or not, but its precision might not be sufficient for determining the absolutely fastest mirror if the candidate mirrors are very close to you. Note that the fastestmirror plugin does not measure bandwidth, but DNS resolution time and the time it takes to establish a TCP connection to each mirror. There can be small fluctuations in these measurements.

One way to guarantee your mirror's inclusion in the top 10 (at least at this moment) would be to make your mirror available over IPv6, and make the mirrorlist.centos.org<http://mirrorlist.centos.org> request from an IPv6-enabled host. mirrorlist.centos.org<http://mirrorlist.centos.org> returns only IPv6-capable mirrors if accessed via IPv6. There are currently five IPv6-enabled mirrors in Illinois.

Some people have suggested "overriding" mirrorlist.centos.org<http://mirrorlist.centos.org>, but I'm not a fan of that approach. That would break if mirrorlist.centos.org<http://mirrorlist.centos.org> switched to using https, or if centos.org<http://centos.org> started using DNSSEC. My own approach for my own unpublished private mirror is to drop a .repo file like this in /etc/yum.repos.d:

---
[b]
name=CentOS-$releasever - Base
baseurl=http://mirror.example.com/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

[u]
name=CentOS-$releasever - Updates
baseurl=http://mirror.example.com/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7

[e]
name=CentOS-$releasever - Extras
baseurl=http://mirror.example.com/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
---

The trick here is that the default CentOS repositories would also remain active. When yum sees that the update is available from both the "updates" repository and the "u" repository, yum will download the package from the repo whose name is the shortest. This way it is not particularly harmful if the local mirror is not up-to-date for some reason, the other packages that are not on the local mirror will get downloaded from other mirrors instead. Obviously this does not meet the "default yum settings" criteria, but this should still be easy enough to accomplish using some sort of configuration management tool.


Eric K. Miller kirjoitti 10.11.2018 klo 13.36:
Ah - makes sense.  I was hoping that our mirror would be selected for
our own systems every time, since the latency is quite a bit lower than
other mirrors (1ms to 2ms, but still...  would be nice to pull from our
own repositories with default yum settings).  Is there anything we can
do?
Thanks for the quick response!
Eric
-----Original Message-----
From: CentOS-mirror [mailto:centos-mirror-bounces at centos.org] On
Behalf
Of Anssi Johansson
Sent: Saturday, November 10, 2018 5:33 AM
To: centos-mirror at centos.org<mailto:centos-mirror at centos.org>
Subject: Re: [CentOS-mirror] CentOS mirror

Yes, the list includes only 10 entries. There are 11 mirrors in
Illinois, so there is a smallish chance that sometimes your mirror
doesn't get included in the 10 selected mirrors. The mirrors are
picked
randomly, and this process is repeated every 10 minutes or so.

Your mirror is not being neglected, ihere was just a bit of bad luck
this time :)
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