Re: Backup mirror machine

From: Bill Moseley (moseley_at_hank.org)
Date: 05/06/05

  • Next message: Igor: "Re: montar particion fat32 correctamente" 
    Date: Thu, 5 May 2005 22:44:34 -0700
To: debian-user@lists.debian.org

    On Thu, May 05, 2005 at 03:30:46PM -0700, Alvin Oga wrote:
    > one script ... change-me-from-slave-to-master.sh and symlinked to "N"

    But that system turns out to be harder to keep in sync.

    > > What I'd like to do, I think, is have a system that ran as a separate
    > > machine, but I could reboot and at the LILO prompt select another
    > > configuration that makes it boot with the other machines IPs and
    > > config settings.
    >
    > you cannot tell lilo to boot a remote machine

    No, I'm not asking that. I was thinking I could use lilo to boot a
    different configuration. I suppose I could use the init scripts to
    setup symlinks for /etc/network/interfaces and for all the services I
    run. That's basically what I have now -- but I've found it hard to
    manage.

    So, I was thinking more of a system that uses rsync to keep a copy of
    the files that make "master" what it is (a machine with specific IPs,
    and a collection of services configured a specific way, and data) on
    the "slave" machine. And then have a way to reboot the slave machine
    and have it start using the backup data making it act as the master.

       if ( running_as("slave") )
            ln -s /slave.etc /etc
            ln -s /slave.var /var
            [...]
        else
            ln -s /master.etc /etc
            ln -s /master.var /var
            [...]

    Or maybe mount the dirs instead.

    Considering /etc/fstab is needed at boot, it's not that easy to place
    /etc on a separate partiton (initrd would be one solution, I
    suppose), or to symlink late in the boot process.

    Perhaps dual-boot would be a good way to go. Boot normally in "slave"
    mode and mount partition(s) under /backup and rsync from the master
    machine to the slave's /backup/etc, /backup/var, etc. dirs.

    Then when there's a failure in master, power down master, and reboot
    the slave machine into "master" mode which then mounts that partition
    or partitions at /etc, /var, etc.

    But, I still don't see that working since the backup of master onto
    slave will contain hardware dependent settings that don't work on
    slave -- like /etc/fstab. I'm not sure what else (/etc/modules,
    perhaps).

    I often wonder why there's not two /etc directories -- one for
    machine specific settings and another for application settings that
    don't really depend on a specific hardware configuration.

    > > Any Suggestions?
    >
    > gazillion ways to do it

    Thanks, but I was only looking for one or two. 

    -- 
Bill Moseley
moseley@hank.org
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  • Next message: Igor: "Re: montar particion fat32 correctamente"

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