Re: Need advice on cloning Debian server
On Tue, 29 May 2012 12:35:40 +0800
Joe Aquilina <rhadmirri@westnet.com.au> wrote:
>
> My thought is that I should install Debian squeeze on to it and get
> it running with RAID & LVM, with partitions, logical volumes etc.
> matching the original file server, and then use rsync to copy all the
> data files over the internal network. I expect that this, as a
> minimum, will mean a new IP address for the new box, fstab, hosts and
> other changes on it compared to the original server.
>
> Is this likely to be a major issue to sort out once the new system
> has been setup?
Probably not major, but many minor issues depending on how long the
server has existed, and how many custom scripts are installed. A lot
depends on what software is installed.
> If so, what would the best way to "fix" the new
> system once Debian is installed onto it? Can I also rsync the
> contents of the /etc, /usr, /var, /boot, /root etc. directories or
> will this cause problems (I suspect it will)? Is there anyway of
> creating as exact a clone of the old system onto the new hardware as
> possible? If so, how do I achieve this?
No, I don't think so. You would use the dpkg --get-selections method to
install the same software, and in many cases the same configuration
file would work, but not all. Quite likely, you're moving from 32 bits
to 64, so all new software is a good idea, even if the 32-bit version
should work. Using grep to search /etc and /var will help for most
things. If you use bind, make sure you know where its databases are, as
there are two popular locations. Don't bother copying mysql or openldap
files, dump the databases to SQL and LDIF respectively, and import,
and do this if you can with other software that maintains databases.
>
> Any guidance or advice from those much wiser and more knowledgeable
> than me would be appreciated.
>
Maybe 'more experienced'. I'm in the final stages of doing this with a
home/small business server. and tentatively shut the old one down
yesterday. I think it's all over, but I'm not moving it until I'm
certain. I haven't got around to testing the Radius server yet, and
possibly other lesser-used things, and there are probably a few more
gotchas to come.
Don't forget the client machines. Ideally they should have automatic
everything, and nothing should need to be changed, but shortcuts may
have been taken in the past to get things working and IP addresses or
hostnames may be hard-coded here and there.
I use two workstations, one Windows 7 and one Debian sid, and a laptop
running Windows XP most of the time. None of them would get a DHCP
address from the new server. I could see nothing wrong, though it
looked as if hardly any broadcasts were happening. I set fixed
addresses and carried on with more important things. I didn't change
anything in the DHCP server (apart from addresses and hostnames, the
old config file had been suitable, as with the sid DHCP client) and had
reset the laptop to automatic for use somewhere else. A few days later,
I realised it was working fine on the home network and on checking, it
had clearly picked up DHCP OK. The sid machine would now work with
DHCP, and only the Win7 machine is still giving trouble, but now I am
confident the DHCP server is OK. The clients, including a sid machine,
seem to have had great difficulty in transferring their allegiance to a
new server. The old DHCP server was, of course, one of the first
daemons shut down.
Another gotcha is samba. If you're making use of browsing of shares,
reduce the OS level of the old samba server. If you don't, the new
server will never win a browser election, and that will cause some
subtle problems. You'll still be relying on the old server to collect a
browse list. If as in my case, the servers are two-NIC machines
functioning as firewalls, and you pull out the external connection of
the old machine, it will not see any shares in that network. I spent
about two hours chasing that one down.
Best of luck.
--
Joe
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