[CentOS] Best way to duplicate a live Centos 5 server?

Wed Jul 11 15:11:18 UTC 2012
Les Mikesell <lesmikesell at gmail.com>

On Tue, Jul 10, 2012 at 11:59 PM, Emmanuel Noobadmin
<centos.admin at gmail.com> wrote:
> On 7/11/12, Les Mikesell <lesmikesell at gmail.com> wrote:
>> Hours?  This should happen in the time it takes to transfer a
>> directory listing and read through it unless you used --ignore-times
>> in the arguments.  If you have many millions of files or not enough
>> RAM to hold the list I suppose it could take hours.
> Not that many files definitely, more in the range of tens of
> thousands. But definitely more than an hour or two with small bursts
> of network traffic.

Perhaps you have some very large files with small changes then
(mailboxes, logfiles, db's, etc.).  In that case the receiving rsync
spends a lot of time copying the previous version of the file in
addition to merging the changed bits.

>> Rear 'might' be quick and easy.  It is intended to be almost
>> unattended and do everything for you.  As for extra software - it is a
>> 'yum install' from EPEL.   The down side is that if it doesn't work,
>> it isn't very well documented to help figure out how to fix it.    I'd
>> still recommend looking at it as a backup/restore solution with an
>> option to clone.  With a minimum amount of fiddling you can get it to
>> generate a boot iso image that will re-create the source filesystem
>> layout and bring up the network.  Then, if you didn't want to let it
>> handle the backup/restore part you could manually rsync to it from the
>> live system.
> I'll look into it when I need to do this again. It just isn't
> something I expect to do with any regularity and unfortunately server
> admin isn't what directly goes into my salary so it has to take a
> second priority.

ReaR's (Relax and Restore) real purpose is to be a full-auto restore
to the existing hardware after replacing disks, etc., something that
is relatively hard to do with complex filesystem layouts (lvm, raid,
etc.) and something armchair sysadmins are likely to need when they
least expect it.  It does that function pretty well with a couple of
lines of config setup (point to an NFS share to hold the backup) for
anything where live tar backups are likely to work.  The whole point
of the tool is that you don't need to know what it is doing and pretty
much anyone could do the restore on bare metal.  Using it to clone or
to move to a modified layout is sort of an afterthought at this point
but it is still not unreasonable - it is just a bunch of shell scripts
wrapping the native tools from the system but you have to figure out
the content of the files where it stores the layout to build.

   Les Mikesell
     lesmikesell at gmail.com