Newbie Question On Installation Over Existing Linux

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If I choose to do a fresh install of CentOS 6 with “replace existing Linux systems“, will it also wipe out my /home directory? In the past when I’ve done this with another Linux distro, /home was not affected.

Or, would I need to do “fresh” install and then muck with partitioning using a Custom Layout? Right now, it’s kind of looking like the latter to me, and if so, will I lose data?

I spent some time on the Forums and reading the RH documentation, but, no real answers to this specific question.

Thanks for any help.

28 thoughts on - Newbie Question On Installation Over Existing Linux

  • Kay,

    Yes it does replace your home directory. When I do a fresh install, I
    back up my home directory on a usb drive and then copy it back after the install. I think you can also ‘muck’ with the partitioning, but I
    have always taken a more conservative route.

    Good Luck!!!

    Greg

  • < <<>>>

    . then you should give some thought to creating a partition for /home.

    such gives you ability to mount the partition as /home and not have to worry about losing, backing up /home.

    that is, you should keep /home backed up, but with it as it’s own partition, you do not have to restore /home into a new install.

    like that better? :-)

  • Maybe some more information about my setup would help.

    My situation is I have 7 separate Linux partitions and a swap area. One of the partitions is /home, so it’s already in its own partition. I want to keep the partitions for CentOS exactly as I have them in terms of size, etc. In the past, even when I’ve done a “clean” Linux install, the existing system partitions were cleared and repopulated, and the existing /home was not touched in any way.

    So, I’m not sure how to interpret what you said. Can I get the same results from a CentOS install using some combination of options?

  • Yes, since you already have a partition explicitly for /home you just need to specify custom partitioning before you begin the install, re-select all your partitions back to the same mount point (you will see them, they just need to be selected and have the mount point specified)
    and make sure that /home (and any other partitions you explicitly don’t want wiped) are not selected for formatting. The installer will take care of the rest.

    Make sure you are backed up just in case you muck things up, but it shouldn’t be an issue.

    Peter

  • < <>>

    because your are playing with multi flavors,
    [i bet you like going to baskin-robbins for ice cream ;-) ]
    a solution for you would be what i did some years back and i was playing with diff flavors, my “/home” partition was mounted in new install as /home2 and i let installation setup a /home in /.

    after install and booting it, as root i moved the newly created
    “user” home to the /home2 directory, renamed it to the ‘user-flavor’, then linked that back into the install /home and renamed it to
    “username” and changed ownership to “user”

    which then gave me:

    /home/username –> /home2/user-flavor

    so that in /home2 i had:

    /home2/geo-fc3
    /geo-fc4
    /geo-mandrake
    /geo-flavor-x
    /geo-flavor-y

    i hope you can see how i did this. i am of terse thinking and do not always go into detail enough.

  • At Sun, 07 Jun 2015 15:16:45 -0700 CentOS mailing list wrote:

    Probably…

    It is not hard to do the custom layout. Just select the ‘system’ filesystems
    (eg /, /usr, /var, /boot, and the like) and select ‘reformat as whatever (ext4
    usually), and set the mount points to what they were. Then select the /home
    (and any other ‘user data’ type file systems) partition(s) and select ‘use as is’ and give the proper mount point(s). If you take your time and are careful, you won’t lose any data, but do go ahead and do careful backups anyway. You *might* want to note down any special configuration information you need to preserve (eg static IP address, a list of custom software you want to have installed, and so on).

    Basically the ‘Custom Layout’ is for two general cases:

    1) you have an unformatted disk and you want to do something non-default with the partitioning.

    2) you want to re-install and retain some non-system data partitions.

    There is a third possibility where you want to have a multiple Linux boot system (this usually means using /boot ‘as is’ for the second+ install, often with the installer bitching about doing that, and it usually means having way too much fun fiddling with grub.conf later), although mostly these days, you just pick one Linux distro for your ‘host’ and run one (or more) ‘other’
    linuxes as VMs.

  • YAY! I think this is exactly what I did at one time. OK, I’ll back up JUST in case, but I am hoping this solution plays out well. :)

  • Kay Schenk wrote:
    install,

    Good fer you. Btw, coming to this thread late, let me note that this is standard for everywhere I’ve worked: make a partition (or nfs mount) for
    /home, or /data, or whatever, so that when you did an upgrade to the next full release, you could say “install”, rather than update, and “sure, wipe my / and /boot (but not anything else).

    mark

  • only thing that some might call a disadvatage is only thing that some might call a disadvatage is only thing that some might call a disadvatage is only thing that some might call a disadvatage is only thing that some might call a disadvatage is only thing that some might call a disadvatage is

    did you do more than just think about it?

    just what do you want for a 1st choice?

    advantages of /home2 is you have a user home directory for all your flavors sitting in 1 partition that will not get erased because you are allocating it’s own mount point when you install.

    because you are using thunderbird for email client, you can set up Mail, ImapMail, News paths in there own director,

    same applies to firefox bookmarks, passwords, certificates, etc. such as;

    /home/moz/
    /moz/firefox
    /moz/thunderbird

    then link them to your ‘flavor’ user directory. same goes for your address book files abook.mab and abook-XX.mab, and other directories and files that are not path critical.

    only thing that some might call a disadvantage is all moz progs will be same, unless you happen to need something in an add-on that is path specific.

    there are many other progs that are not ‘hard set’ with path names.

  • I think Peter addressed my concern and responded in a way that leads me to believe a /home2 as you suggest is not necessary since it will be bypassed in terms of any installation, which is what I want.

    I do not have and do not want one partition for my system (files). I
    have ONE flavor with many partitions and mount points. A rather “old school” approach that’s worked pretty well for me all these years.

  • < <<>>>

    true he went into detail. during install of os, the option of
    *custom* allows you to ‘slice and dice’ a disk into however many proportions of what ever size you desire.

    custom allows creating partitions and setting mount points for _all_
    partitions for what ever root path you want. this is how home2 is how to mount and get /home2.

    i never said you had to use one partition for any files.

    multi partitions for / paths is not really “old school”. it is a feature of “custom”. you define what each partition is use for.

    ie, partition for boot, partition for swap, partition for /, partition home, partition for usr, partition for var, partition for home2, partition for what ever.

  • that model is not generally recommended anymore, at least not putting
    /usr on its own partition, there’s just too many issues with that nowdays. I don’t like putting /var in its own partition either as its all too intertwined with root. the problem with lots of little partitions is your freespace gets fragmented.

    /home in a dedicated partition, sure.
    /var/lib/${DATABASE_OR_WEB_SERVER}, ditto…

  • The real issue is that you cannot put /usr on a dedicated partition anymore as of CentOS 7. This is because /bin, /lib and /lib64 are symbolic linked in the /usr equivalents now. The (previous) purposes of having a separate /bin and /lib was so that programs and libs required at boot time could be run before the rest of the fs was mounted up if
    /usr were on a separate partition. Now they’ve been consolidated and symlinked so if you put /usr on a separate partition then the system won’t be able to access critical apps during boot.

    You can thank Fedora for making that rather pointless change and breaking that capability.

    Peter

  • i agree with you 100%.

    op inferred that i told him to put everything in 1 partition, which i did not. so i was just telling him if he wanted to be ‘old school’
    he could partition what every his heart desired. ;-)

    for my ‘base’ os partitioning is /boot, swap, /, /home.

    all additional installs are /, swap, /home. after install if/and install part 2 boot, i restart to base, i log in as root, copy grub.conf into /grub of base /boot as grub.conf-newosname. then i cut/paste lines into my main grub.conf. make notations in ‘title’
    line. next i copy base /root files that customize user root so i have same ‘root’ operation across all installs. the i reboot to new install and set it up.

    only way i have done it from many years back.

    if/when i set up a server.

  • Servers are better off without a separate partition for /home. Unlike desktop installs which contain pretty much all of the user data under
    /home in a server install there isn’t very much “user” data at all and most of the actual data is contained under /var somewhere.

    That said, if you plan on having multiple users who will store some data in their individual /home directories then /home might be in order for a server, it all depends on your individual needs, it’s just that on a server I don’t automatically create a massive /home like I would on a desktop.

    Peter

  • < <>>

    _but_, you can/could have a minimal /usr with required files for boot. then after the mounting, usr partition lays in.

    there are a lot of ‘thank yous’ for fedora project. 1 of which made
    3 of my drive lvm when they were ext4. :-\

  • that ‘capability’ was a holdover of the 1980s when disks were measured in megabytes, and memory in kilobytes, so large file systems were impractical.

  • I tend to install my virtual host websites under
    /home/someuser/public_html where there’s a someuser for each vhost. the default /var/www website is generally completely stubbed off and not even used.

  • That was actually one of the scenarios that I had in mind when I added the 2nd paragraph to my comment (that you snipped).

    Peter

  • Just curious what happens in this case. Do the apps wait and/or retry until /usr is mounted or does the boot fail?

  • partition partition for what ever.
    /usr on its own partition, there’s just too many issues with that nowdays. I don’t like putting /var in its own partition either as its partitions is your freespace gets fragmented. anymore as of CentOS 7. This is because /bin, /lib and /lib64 are symbolic linked in the /usr equivalents now. The (previous) purposes of at boot time could be run before the rest of the fs was mounted up if
    /usr were on a separate partition. Now they’ve been consolidated and symlinked so if you put /usr on a separate partition then the system won’t be able to access critical apps during boot.

    This change looks awfully unprofessional to me…

    breaking that capability. until /usr is mounted or does the boot fail?

    I for one still have /usr living on separate partition on CentOS 7
    workstations which are few (do not and never will run servers under CentOS
    7). And I have sixth field (fs_passno) 2 for /usr in /etc/fstab. Didn’t have problems with these boxes so far. Though fs_passno should probably be changed to 1 (as for /) according to description of new layout (i.e. _all_
    libraries and binaries now physically live in /usr).

    Just my $0.02

    Valeri

    ++++++++++++++++++++++++++++++++++++++++
    Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247
    ++++++++++++++++++++++++++++++++++++++++

  • Yes.

    And this is not a case of Fedora picking fights with the rest of the Linux world. /usr was already assumed to be on the root FS in Solaris, FreeBSD, OS X, and Cygwin well before Fedora made their decision.

    Fedora’s late to the party, and CentOS necessarily even later.

    Unix has never seriously been deployed on 8-bit systems.

    Even oddballs like Xenix on 8088 and uCLinux on H8/300 are only “8 bit” because of the external address bus. These are just gimped 16-bit processors, not true 8-bitters.

    Unix started out on a PDP-7, an 18-bit machine, before moving to a PDP-11/20, which was 16-bit, but much more powerful than the -7. The reduction in word size is a reflection of the rise of ASCII and power-of-2 data size standards, not indicating any real reduction in power.

    I don’t know about *any* 17-bit processors.

  • Warren Young wrote:

    I’m using both Solaris and FreeBSD quite extensively and, honestly, have never heard of that assumption. In fact, on the machine that I’m currently typing this message on, the file systems look like this:

    # uname -sr; mount -t ufs
    FreeBSD 10.1-RELEASE
    /dev/da0s1a on / (ufs, local, journaled soft-updates)
    /dev/da0s1d on /tmp (ufs, local, journaled soft-updates)
    /dev/da0s1e on /var (ufs, local, journaled soft-updates)
    /dev/da0s1f on /usr (ufs, local, journaled soft-updates)

    (Everything else, especially /home, is NFS-mounted.)

    Patrick

  • I don’t have a “real” Solaris installation here to try, but the OpenIndiana, DilOS and SmartOS forks of OpenSolaris all symlink /bin to /usr/bin. I expect the same is true of Solaris 11, though I wouldn’t be surprised to learn that Solaris 10 still kept /usr separate, given its 2005 release date.

    As for FreeBSD, I’m basing that on the fact that the last time I tried moving /usr to a ZFS volume, back in the days when it could only boot to UFS, the system couldn’t even boot into single user mode. I had to reinstall the OS to fix that box.

    I suspect if I tried UFS-root + ZFS-/usr again today, on a 10.1 box, it would succeed as a side effect of the root-on-ZFS support, but only because it would allow /usr to come up early enough to allow the boot to proceed. I suspect if you nuked /usr, it again would fail to boot.

    The bottom line is that we now live in a world where even the piggiest OSes will install with room to spare on a throwaway removable flash drive. The rationale behind /usr-free single-user boots is defunct.

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