[CentOS] How to update CentOS 5.4 to 5.6?

Fri Sep 23 13:07:21 UTC 2011
Johnny Hughes <johnny at centos.org>

On 09/22/2011 06:20 AM, Rudi Ahlers wrote:
> On Thu, Sep 22, 2011 at 12:37 PM, John R Pierce <pierce at hogranch.com> wrote:
>> On 09/22/11 3:08 AM, Sebastian Schubert wrote:
>>> Am 22.09.11 11:59, schrieb John R Pierce:
>>>>>  On 09/22/11 2:13 AM, John Doe wrote:
>>>>>>>  If you want to take the risk anyway, the following (untested) might work:
>>>>>>>  Modify your /etc/yum.repos.d/CentOS-Base.repo
>>>>>>>  try to replace the baseurl's $releasever with 5.6...
>>>>>
>>>>>  no, as the 5.6 specific files are removed when 5.7 is released. you'd
>>>>>  have to get a clone of the vault's 5.6 directory and set that up as a
>>>>>  local repository instead, then point the repo file to that.
>>> crap ... the 5.6 files are still there .. just change the baseurl like
>>> john doe wrote and you'll get an update to 5.6
>>
>> no, they aren't.
>>
>> http://mirror.centos.org/centos/5.6/
>>
>> empty.  except a readme file telling you to look in /5/ instead, which
>> has the 5.7 stuff in it.
>>
> 
> 
> 
> Why would the 5.6 stuff have been removed?
> 
> Apart from the "5.7 is more secure" answer, or even "we're running out
> of disk space", what is the actual reason behind this?
> 
> surely a few versions of the OS won't take up that much space? 1TB &
> 2TB HDD's these day cost a few dollars so I don't think that's the
> real reason. And it can't be bandwidth either since the files are
> mirrored to many other servers around the globe.
> 
> 

They are removed because they do take up too much disk space.

The CentOS project has to maintain dozens of servers as mirrors/rsync
machines.  We have to sync to hundreds of external (that is, not
maintained by the CentOS Project ... but can be used by CentOS users)
mirrors

All of our internal (the ones maintained by the CentOS Project) Mirror
servers are donated by hosting providers and we only get what they are
willing to donate.  If they give us a machine with a 1 TB drive, great.
 If it has 500GB, that is what we get.  Some of them upgrade us, some
don't.  We can only have a "repository to mirror" that is as large as
the "smallest drive" on the machines we want to use a a mirror.

As we increase the size of the repo, we drop more and more machines out
of the list of machines we can use a mirror/rsync machines.  Not to
mention that we eliminated people externally who can mirror CentOS for
users.

You have to remember that there are millions of CentOS machines that
update and we have to not provide 1 location that contains all the
files, but enough locations available that contain all of the files to
serve several million users.

So, you say, just upgrade the machines to a bigger hard drive.  Well
that is much harder than you would imagine.  First off, they are not OUR
machines.  Secondly, if they were OUR machines, we would need to buy the
drives and pay someone to install them as we have machines all over the
world.  (As a side note, we are managing internal CentOS Project
machines in 12 countries on 5 continents)

If you wanted to upgrade 250 servers, and if you wanted to pay $200.00
each for one of those cheap hard drive to do it ... then that would be:

250 x $200.00 = $50,000.00

I don't know about you ... but I can't write a $50K check to make that
happen.  If you can, I'll send you my address.

Even if we DID have the space on the CentOS machines, there would be the
time (and bandwidth) required to stand up a new mirror or to maintain
all the old mirrors.  This gets significantly longer if we maintain all
the trees on all the servers.  The vast majority of requests are only
for the latest tree ... but the releases would be significantly delayed
to move around old trees.

So, we only mirror as installable, the latest of each of the supported
versions.  The rest we maintain available in archive at
vault.centos.org.  You can download and use those yourself if you want
to do so.



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