writing logs in /var/adm/utmp vs /var/adm/utmpx

have 2 similar rhel6 servers but they behave different, while one creates login records in /var/adm/utmp, the other logs in /var/adm/utmpx, bot thave the same kernel and grub.conf configuration.

We’re planning on replacing these servers soon but still, it puzzles me.

here are the grub.conf files for each:

Server1:

# grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE:  You have a /boot partition.  This means that #          all kernel and initrd paths are relative to /boot/, eg. #          root (hd0,0) #          kernel /vmlinuz-version ro root=/dev/mapper/rootVG-rootVol #          initrd /initrd-[generic-]version.img #boot=/dev/sda default=0 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu password --encrypted <removed> title Red Hat Enterprise Linux Server (2.6.32-754.14.2.el6.x86_64)     root (hd0,0)     kernel /vmlinuz-2.6.32-754.14.2.el6.x86_64 ro root=/dev/mapper/rootVG- rootVol rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=rootVG/rootVol  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet     initrd /initramfs-2.6.32-754.14.2.el6.x86_64.img title Red Hat Enterprise Linux Server (2.6.32-754.10.1.el6.x86_64)         root (hd0,0)         kernel /vmlinuz-2.6.32-754.10.1.el6.x86_64 ro root=/dev/mapper/rootVG-rootVol rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=rootVG/rootVol  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet         initrd /initramfs-2.6.32-754.10.1.el6.x86_64.img 

Here is server2:

# grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE:  You have a /boot partition.  This means that #          all kernel and initrd paths are relative to /boot/, eg. #          root (hd0,0) #          kernel /vmlinuz-version ro root=/dev/mapper/rootVG-rootVol #          initrd /initrd-[generic-]version.img #boot=/dev/sda default=0 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu password --encrypted <removed> title Red Hat Enterprise Linux Server (2.6.32-754.14.2.el6.x86_64)     root (hd0,0)     kernel /vmlinuz-2.6.32-754.14.2.el6.x86_64 ro root=/dev/mapper/rootVG-rootVol rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=rootVG/rootVol  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet     initrd /initramfs-2.6.32-754.14.2.el6.x86_64.img title Red Hat Enterprise Linux Server (2.6.32-754.10.1.el6.x86_64)     root (hd0,0)     kernel /vmlinuz-2.6.32-754.10.1.el6.x86_64 ro root=/dev/mapper/rootVG-rootVol rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=rootVG/rootVol  KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet     initrd /initramfs-2.6.32-754.10.1.el6.x86_64.img