On 03/18/2015 09:47 PM, Phil Wyett wrote:
> On Wed, 2015-03-18 at 20:27 -0700, Yasha Karant wrote:
>> I have been told that SUSE Enterprise Linux (SLES) supports, without 
>> problems or issues, an upgrade in place to migrate from major release N 
>> to N+1 without reformatting those parts of the disk / file system that 
>> contain systems files (e.g., /usr ,  /boot , etc.).  My understanding is 
>> that this is not possible/safe with EL -- e.g., SL6 to SL7.  Does anyone 
>> know if this is true -- and works?  If so, why does EL not support the 
>> same method?
>>
>> Yasha Karant
> 
> Hi,
> 
> This info is from CentOS but explains some of it.
> 
> http://wiki.centos.org/TipsAndTricks/CentOSUpgradeTool
> 
> A server upgrade (no desktop) maybe possible, but a desktop version is
> not possible due to some packages being of higher versions in 6 than 7
> e.g. mesa.
> 
> Regards
> 
> Phil
> 

The current RHEL upgrade tool does quite a lot of work outside of the normal
yum upgrade process to forcefully replace "newer" versions of packages in RHEL
X with  "older" versions in RHEL X+1 (and without using "epochs", and I've
used it successfully in a test server environment.  Unfortunately, the last
time I tried using the CentOS upgrade tool it did not have this ability,
perhaps because it was based on an earlier version of the RHEL upgrade tool.
Maybe they have updated it, but I have no idea.

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