[CentOS] Migrating From CentOS-6 To CentOS-7

Tue Dec 5 18:47:05 UTC 2017
Eugene Poole <etpoole60 at comcast.net>

I asked this in Vol 154, Issue 29:

    I've a system that has been running CentOS 6 64-bit for almost
    4-years and I want to start the move to CentOS 7 64-bit.

    I run software RAID-1 with LVM everywhere except /boot which is a
    standard partition RAID-1.

    There are 2 areas that concern me greatly about this migration:

    1. How do I duplicate my current grub configuration file that
    supports a failure of /dev/sda to grub2?

    2. How do I install CentOS 7 but use my existing hard drive layout
    so I only format specific OS file systems. My drive layout goes back
    to the original proposed FHS layout. The separate partitions related
    to the operating system are:

        /boot        1GB  (standard boot as defined in fstab is /dev/md0)

    The following file systems are all defined in volume group
    vg_jpdopsys (size is 64 GB)

        / (root)      6GB

        /home       4GB

        /opt           4GB

        /tmp          2GB

        /usr            12GB

        /usr/local  2GB

        /var            8GB

    The following file system is defined in volume group vg_jpdswap
    (size is 24 GB)

        swap          16GB

    Plus many other file system dedicated to specific applications and
    data all using logical volume management.

    When I moved from CentOS 5 to CentOS 6 all of the OS partitions were
    formatted except /home.  All went extremely well then.

    But I don't see a way to do that with CentOS 7 retaining the
    existing disk configuration.

    Is there some detailed installation instructions showing some
    advanced methods?



If you saw the original post you will see that I did clean it up a bit.  
I'm starting this move now understanding that I have until 2020 to do it.

Any suggestions?



Eugene Poole
Woodstock, Georgia