Centos 6 requires GLIBC 2.12 however a lot of new programs you would want to compile may need a newer glibc. You can't remove the old glibc since the whole OS is based on it but you can install the updated glibc alongside it and do an export pointing to your updated GLIBC.
mkdir ~/glibc_install; cd ~/glibc_install
wget http://ftp.gnu.org/gnu/glibc/glibc-2.14.tar.gz........
Tired of checking iotop and seeing that your drbd partition is using 99.99% of io all the time and finding your drbd device performs slow in general?
This is especially an issue in versions of DRBD in the 8.3 tree in particular one documented case is on "8.3.13" but it likely applies to other devices.
The symptoms are that resyncing is fine and normal but any reasonable amount of activity is very slow and lagged and creates a high server load and con........