Hello Ken,
I upgraded it using the Redhat procedure.
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/5/html/Deployment_Guide/ch-Migrating_from_MySQL_5.0_to_MySQL_5.5.html
If we use another repo other than theirs and should we encounter problems, the support for MySQL will not be provided. That is why we stuck with theirs and not other repos such as remi, epel, etc.
There is no problem with doing a mysqlsdump as I have tested that already.
[x] yum list mysql\*
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rhel-6-server-optional-rpms | 1.8 kB 00:00
rhel-6-server-rh-common-rpms | 2.1 kB 00:00
rhel-6-server-rhn-tools-rpms | 1.8 kB 00:00
rhel-6-server-rpms | 2.1 kB 00:00
rhel-server-rhscl-6-debug-rpms | 2.1 kB 00:00
rhel-server-rhscl-6-eus-debug-rpms | 2.1 kB 00:00
rhel-server-rhscl-6-eus-rpms | 2.1 kB 00:00
rhel-server-rhscl-6-source-rpms | 1.8 kB 00:00
Installed Packages
mysql.x86_64 5.1.73-5.el6_6 @rhel-x86_64-server-6
mysql-bench.x86_64 5.1.73-5.el6_6 @rhel-x86_64-server-6
mysql-connector-odbc.x86_64 5.1.5r1144-7.el6 @rhel-x86_64-server-6
mysql-devel.x86_64 5.1.73-5.el6_6 @rhel-x86_64-server-6
mysql-libs.x86_64 5.1.73-5.el6_6 @rhel-x86_64-server-6
mysql-server.x86_64 5.1.73-5.el6_6 @rhel-x86_64-server-6
mysql-test.x86_64 5.1.73-5.el6_6 @rhel-x86_64-server-6
mysql55.x86_64 1.1-23.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-mysql.x86_64 5.5.41-2.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-mysql-bench.x86_64 5.5.41-2.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-mysql-debuginfo.x86_64 5.5.41-2.el6 @rhel-server-rhscl-6-debug-rpms
mysql55-mysql-devel.x86_64 5.5.41-2.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-mysql-libs.x86_64 5.5.41-2.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-mysql-server.x86_64 5.5.41-2.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-mysql-test.x86_64 5.5.41-2.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-runtime.x86_64 1.1-23.el6 @rhel-server-rhscl-6-eus-rpms
mysql55-scldevel.x86_64 1.1-23.el6 @rhel-server-rhscl-6-eus-rpms
Available Packages
MySQL-python.x86_64 1.2.3-0.3.c1.1.el6 rhel-6-server-rpms
mysql-connector-java.x86_64 1:5.1.12-2.el6 rhel-6-server-rpms
mysql-connector-java.noarch 1:5.1.17-6.el6 rhel-6-server-rpms
mysql-devel.i686 5.1.73-5.el6_6 rhel-6-server-rpms
mysql-embedded.i686 5.1.73-3.el6_5 rhel-6-server-optional-rpms
mysql-embedded.x86_64 5.1.73-3.el6_5 rhel-6-server-optional-rpms
mysql-embedded-devel.i686 5.1.73-3.el6_5 rhel-6-server-optional-rpms
mysql-embedded-devel.x86_64 5.1.73-3.el6_5 rhel-6-server-optional-rpms
mysql-libs.i686 5.1.73-5.el6_6 rhel-6-server-rpms
[x ~]$
Just for fun I also did an rpm -qa
[x ~]$ rpm -qa | grep mysql
mysql-connector-odbc-5.1.5r1144-7.el6.x86_64
php55-php-mysqlnd-5.5.6-13.el6.x86_64
mysql55-1.1-23.el6.x86_64
mysql55-mysql-test-5.5.41-2.el6.x86_64
mysql-devel-5.1.73-5.el6_6.x86_64
mysql-server-5.1.73-5.el6_6.x86_64
mysql55-mysql-5.5.41-2.el6.x86_64
mysql-bench-5.1.73-5.el6_6.x86_64
mysql-test-5.1.73-5.el6_6.x86_64
mysql-5.1.73-5.el6_6.x86_64
mysql55-scldevel-1.1-23.el6.x86_64
mysql-libs-5.1.73-5.el6_6.x86_64
mysql55-runtime-1.1-23.el6.x86_64
mysql55-mysql-bench-5.5.41-2.el6.x86_64
httpd24-apr-util-mysql-1.5.2-7.el6.x86_64
mysql55-mysql-server-5.5.41-2.el6.x86_64
mysql55-mysql-devel-5.5.41-2.el6.x86_64
mysql55-mysql-libs-5.5.41-2.el6.x86_64
mysql55-mysql-debuginfo-5.5.41-2.el6.x86_64
Probably best to back it up, remove 5.1.x and just put it back as 5.5.x.