[CentOS-devel] Getting there faster

Karanbir Singh mail-lists at karan.org
Sat Nov 9 21:46:25 UTC 2013


On 11/09/2013 01:07 AM, Anssi Johansson wrote:
> One more thing -- if the bandwidth of the msync servers is the 
> bottleneck, we could reduce their bandwidth requirements by serving the 
> CR packages from public mirrors instead of mirror.centos.org. Most of 
> the mirror.centos.org machines are also in the msync.centos.org 
> rotation, thus they share the same bandwidth. I don't have statistics of 
> the bandwidth consumed by CR. Someone who has access to such stats could 
> see if this change would be worth implementing or not.

We certainly need to get smarter about the mirror/msync split - and go
back to the older model we used where msync machines that were seeding
the mirror network were taken out from being in mirror.centos.org - and
we had dedicated box's for some high capacity mirrors ( like kernel.org
and heanet.ie and mirrorservice.org ).

Again, this is a great thing to try and PoC and workout a functional
setup - it would, ofcourse, need to be automated via puppet and managed
mostly via zabbix. If there are manual steps involved, its going to fail
and as has happened already, get discarded since its just more stuff to do.

We usually run hardlink over the entire mirror tree, so that should
solve a large part of the dupe-content-being-rsync'd again.

Another issue we have and we should try and work around is that the
entire tree os/ isos/ repo's/ is moved in at one point - maybe we should
spread those a bit, allowing more rsync' runs to finish sooner ( and
therefore allow subtree rsync's to start earlier ).

The old speedmatrix code I wrote back in 2010 mostly still works, and
gives us a fair idea of what capacity the various msync and mirror.c.o
machines have at a given point in time, and doing it a few times through
a 24 hr cycle is almost always a true picture of reality.

I can get a bunch of VM's online to trial some of these things, but they
will need to be in one play-cloud or something such, does anyone haves
ideas on how one might create 'real world network problems' on a bunch
of VM's ? eg. how do we cap say 25% of the network interfaces to 10mbps,
and how might we generate latency ? I have a bunch of ideas on howto do
this between machines, but not so much on VMs running on the same ( or
just a few ) machines.

- KB
-- 
Karanbir Singh
+44-207-0999389 | http://www.karan.org/ | twitter.com/kbsingh
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