ISSUE SUMMARY
Previously, an update of MongoDB with yum from 2.4.x to 2.6.0 required removing the package, followed by installing the package again. This resets the default mongod.conf file and can overwrite any customizations that were made to the file.

USER IMPACT
Users might not be aware of this behavior and restart their instances with the new default config file, which can have serious impact to a production system or prevent the instances from starting at all (for example due to the new bind_ip default, which is set to localhost in 2.6).

WORKAROUNDS
Users should make a backup of their mongod.conf file before the upgrade, and restore it before restarting the instances again. We also advise to review the new defaults in the 2.6 config file, and incorporate any desired changes.

RESOLUTION
The old package names have been added to the "Provides" and "Obsoletes" fields in the RPM spec, for both the community and enterprise packages. This now allows a direct update (rather than remove/install), as well as other scenarios, like installing sub-packages or meta-packages.

Note: Upgrading from a previous major release branch (e.g. 2.4.8) will now upgrade to the latest available stable release (e.g. 2.6.1). Additionally, users who want to downgrade to (or install) an older version of MongoDB now require additional flags, as described on our page about RPM Package Installation.

AFFECTED VERSIONS
Verson 2.6.0 is affected by this bug.

PATCHES
The patch is included in the 2.6.1 production release.