[CentOS-devel] 5.3´s anaconda src.rpm missing

Lamar Owen lowen at pari.edu
Thu Apr 9 15:21:27 UTC 2009


On Wednesday 08 April 2009 17:36:18 R P Herrold wrote:
> I would be thrilled to have a simultaneous coordinated
> release, but the 'leak' of 'patched' torrent instances, and at
> least two mirrors opening the full ISO set before the
> coordinated bit flip date and time, leave rather a bad outlook
> to me as to the ability to make things better through such an
> 'inverted as to demand' approach

> My $0.02 .... I'd love to be shown a path to avoid the
> problems on the 5.3 roll-out

Russ, Karnbir, et al:

First, a marvelous job on getting the bits out at all; it ain't easy doing 
this for free (did it on a smaller scale with the PostgreSQL RPMs years ago).  
I greatly appreciate what the CentOS team does, and how rapidly it gets done.  
It certainly gets done faster than if I were doing it from the upstream EL's 
SRPMS.

Now, as to the technical issues, it seems to me that a fully ACID compliant 
transactional repository mirror system is possibly one way to eliminate most 
of these issues.  Such a system to my knowledge does not yet exist; but, to 
use an SQL example, something like:
BEGIN;
MIRROR repo WHERE release = "5.3" AND arch = "x86_64";
COMMIT;
and the COMMIT would atomically bring the repo and its mirrors into a 
consistent state, with already connected clients isolated from the changes as 
they are being made and with a durability of the result. (yes, wording is 
intentional).  Errors would block the COMMIT until the errors are resolved on 
a mirror-by-mirror basis; that is, either a mirror shows the full consistent 
set or it doesn't show anything until it gets the full consistent set and a 
replica commit occurs.  A critical mass of replicas committed would be 
required to cause a repo commit to avoid overload of individual mirrors.

This is doable now with databases of many gigabytes (I'm in the process of 
beginning reception of a long term sneakernet push replica/mirror of over 10TB 
of image data, and the mirror has to be atomic, and it is of course on a 
database system). But the current pull updating structure doesn't lend itself 
readily to this. 

Incidentally, the MIRROR statement above is intended to project a PUSH 
arrangement instead of a PULL arrangement; the SQL above would be run on the 
master to push out the mirrors which could then propagate down hierarchically; 
reminds me of master-slave database replication with submasters.  The fact 
that some mirrors are partials complicates things even further, though.

Yes, such a system would be a large technical hurdle, and perhaps it would be 
too complex to work in a loose volunteer arrangement.  But surely other 
upstream projects and distributions have similar issues and needs; perhaps a 
transactional mirrornet 'system' would be a fine project for someone to start.  
If one doesn't already exist, that is.  

A revision control system can be pressed/abused into this sort of service; 
monotone, for instance, is/was used by the OpenZaurus people to consistently 
push out packages, and git is being used by vyatta for similar things, mostly 
on the developer's side of things (see 
http://www.vyatta.org/downloads/glendalebuild ).  Git has the distributed 
aspects going for it, but it's not optimal.

Just some ideas.
-- 
Lamar Owen
Chief Information Officer
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
http://www.pari.edu


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