 | | | clone a linux system over the network | clone a linux system over the network 2005-05-06 - By Garrick Staples
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On Fri, May 06, 2005 at 09:16:03PM +0200, wolf2k5 alleged:
> Hi,
>
> I need to migrate a Linux system from a server to another one.
>
> I cannot reinstall the OS and applications on the new server and then
> migrate the data from the old server, since that would require too
> much time.
>
> In the past, to migrate a Linux system from a server to a new one with
> HD of the same size, I shut down the servers, booted a Linux live CD
> (Knoppix) on them and used 'dd' and 'netcat' to clone the system over
> the network: that worked fine, but with two cons:
>
> - It is pretty slow, since it will copy over even blank data.
>
> - You cannot resize the partitions: if the new server has a bigger
> disk, you cannot enlarge the original partition to use the additional
> space.
You should be able to fsck and use the filesystem's grow utility (resize2fs,
resize_reiserfs, etc.) after you dd the partition.
> Do you know any better way to clone the system over the network that
> will fix the above problems?
rsync instead of dd? That will just copy files. Be sure to use --sparse.
My larger servers tend to have spare internal disks that are informal mirrors
of the real boot disks. I manually rsync them from time-to-time so that I
always have something relatively recent to boot.
I've done OS upgrades by installing the new OS on a test box, and rsyncing from
the test box to the server's spare disks and rebooting then just rebooting to
the new disks. Obviously this is a very error-prone method because you need
worry about boot partitions, boot loaders, device names, fstab, etc.
> I think the commercial application Symantec Ghost can do it, but I am
> looking for something free.
>
> It would be great if such tool supported PXE boot too.
>
> On a separate note, do you know how to boot Knoppix via PXE without
> using the Knoppix Terminal Server (that requires an additional
> machine)?
> I already have a Linux host running TFTP/DHCP/NFS servers and use it
> to perform Red Hat Enterprise Linux installations via PXE.
> How do I configure it to perform Knoppix boots via PXE?
I haven't found a way to boot an ISO image over the network. I can netboot
linux and dos floppy images (dos floppies are useful to automate BIOS/firmware
updates over the network).
--
Garrick Staples, Linux/HPCC Administrator
University of Southern California
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