I read at <http://wiki.centos.org/TipsAndTricks/CentOSUpgradeTool> "Warning: use of this tool is currently not recommended as several system-critical packages are of a higher version number in CentOS 6.6 than they are in CentOS 7 so those do not get upgraded correctly. This renders yum and several other system tools non-functional." Is that still the position? If so, is it likely to change in the near future? -- Timothy Murphy gayleard /at/ eircom.net School of Mathematics, Trinity College, Dublin