The best way to upgrade CentOS from 5.5 to 6.6 on HP Proliant DL180 G6

[Ajaybaskin]

Hello please let me know the best way to upgrade CentOS from 5.5 to 6.6 on HP Proliant DL180 G6

[Jimmy Vance]

You can search around and find various comments on ways this can or cannot be accomplished. If you look at the release noted for CentOS 6, they do not recommend an in place upgrade.

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Upgrading from CentOS-4 or CentOS-5:

We recommend everyone run through a reinstall rather than attempt an
inplace upgrade from CentOS-4 or CentOS-5

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http://lists.centos.org/pipermail/centos-announce/2011-July/017645.html

[drayson]

Upgrading from EL5 to EL6 is not provided or supported (neither by Red Hat or CentOS)

You need to do a fresh installation.