Hi guys:
I'm about to migrate a sever to a managed server facility. I've alwau=ys used tape to backup my server, now that's not an option. I've read abut using rsync to do backups and have several scripts to do same. I believe rsync is a good solution.
I am missing some important nuiances though... I would like to have essentially a "mirror" server at my facility ( call it "master") that I can backup to, and from, completely from the other server (call it "hosted").
Obviously I have to have at least different IP addresses on "master" and "hosted", but other than that, I'd like them to be mirrors of each other. I would like to do all my configs, setup, etc. at my leisure on "master", where I have hands on control, then when ready, have "hosted" setup with a basic Centos server install, then configure it to rsync to my "master" and update the entire thing (updates and all) to my "master".
1. Which files tdo I need to exclude to avoid IP address and hostname changes?
2. What caveats do I need to be aware of? Are there other files such as 'live" libraries that I cannot sync to?
3. The "master" server at my facility and their server may have different hard drive architecture (i.e. IDS and SCSI drives, different processor, etc.). As long as I use a generic Kernel (i.e. stock) that supposts the hardware on both, this shoudl not be a problem, right?
4. Am I missing something, is there a better way?
Thanks, Scott
On Thu, 2005-07-07 at 11:56 -0500, scott wrote:
Hi guys:
I'm about to migrate a sever to a managed server facility. I've alwau=ys used tape to backup my server, now that's not an option. I've read abut using rsync to do backups and have several scripts to do same. I believe rsync is a good solution.
I am missing some important nuiances though... I would like to have essentially a "mirror" server at my facility ( call it "master") that I can backup to, and from, completely from the other server (call it "hosted").
Obviously I have to have at least different IP addresses on "master" and "hosted", but other than that, I'd like them to be mirrors of each other. I would like to do all my configs, setup, etc. at my leisure on "master", where I have hands on control, then when ready, have "hosted" setup with a basic Centos server install, then configure it to rsync to my "master" and update the entire thing (updates and all) to my "master".
- Which files tdo I need to exclude to avoid IP address and hostname
changes?
/etc/sysconfig/network /etc/sysconfig/network-scripts/ifcfg-eth0
Likely also want to exclude: /etc/sysconfig/hwconf /etc/fstab /etc/mtab /etc/ssh/ /root/.ssh/ /boot/grub/grub.conf /boot/grub/device.map
Will need a /etc/hosts that is compatible with both machines. I'm no doubt forgetting some others to exclude.
- What caveats do I need to be aware of? Are there other files such as
'live" libraries that I cannot sync to?
Doing this to a live system is VERY likely to be problematic. How about a ping-pong approach where you keep two bootable systems on the "hosted" system (on different partitions or physical disks) and update the one not being used, fix up grub and other files (see below), and reboot to the new image. Gives you the untouched installation to fall back on, but could still be a problem if boot fails and you have nobody on-site to help.
- The "master" server at my facility and their server may have different
hard drive architecture (i.e. IDS and SCSI drives, different processor, etc.). As long as I use a generic Kernel (i.e. stock) that supposts the hardware on both, this shoudl not be a problem, right?
May need to run mkinitrd on the "hosted" machine if the hardware is different, edit /boot/grub/grub.conf, and possibly /etc/fstab and /etc/mtab, before booting to a new kernel. In the past, I've found the existence of /etc/mtab~ to cause problems on reboot, so watch out for cleaning up the backup file if using emacs or another editor that uses that convention.
- Am I missing something, is there a better way?
Would work better, involve less manual fix-up, and be less error-prone to have identical hardware.
I'd consider just keeping a local backup image of the "hosted" machine for disaster recovery, and perhaps use a local "slave" (as opposed to "master") system for testing updates before installing them on the "hosted" system. Could still use rsync for backups without worrying about excludes.
Phil
My advice to you is rsync'ing the whole machine is never going to work without problems.
You should concentrate on rsync'ing data partitions and simple configs that may accompany the data sets eg: httpd.conf or /etc/mail
You may wish to tar up the config files for each of the setups you are using, and rsync the tar ball to the remote machine.
Then write a script to untar and restart services if configs (tar ball) changes.
Forget the idea of rsync'ing the kernel especially if the hardware is different, what real operational benefit is this going to give you for something that will generate a lot of problems?. I can see that the only possible benefit is that you test on the local machine and then rsync the config to the hosted machine, for offline testing of configs, the concept of rsync ing in the manner you describe will create so many other unknowns or problems it will almost certainly cloud the validity of your test bed and its processes anyway.
The best way to truly test in the manner you describe is to have identical machines and then create a config on one and replicate it by hand onto the other when you are happy the config is good. Trying to do it automagically will imho screw it up in some other way....
P.
scott wrote:
Hi guys:
I'm about to migrate a sever to a managed server facility. I've alwau=ys used tape to backup my server, now that's not an option. I've read abut using rsync to do backups and have several scripts to do same. I believe rsync is a good solution.
I am missing some important nuiances though... I would like to have essentially a "mirror" server at my facility ( call it "master") that I can backup to, and from, completely from the other server (call it "hosted").
Obviously I have to have at least different IP addresses on "master" and "hosted", but other than that, I'd like them to be mirrors of each other. I would like to do all my configs, setup, etc. at my leisure on "master", where I have hands on control, then when ready, have "hosted" setup with a basic Centos server install, then configure it to rsync to my "master" and update the entire thing (updates and all) to my "master".
- Which files tdo I need to exclude to avoid IP address and hostname
changes?
- What caveats do I need to be aware of? Are there other files such as
'live" libraries that I cannot sync to?s
- The "master" server at my facility and their server may have different
hard drive architecture (i.e. IDS and SCSI drives, different processor, etc.). As long as I use a generic Kernel (i.e. stock) that supposts the hardware on both, this shoudl not be a problem, right?
- Am I missing something, is there a better way?
Thanks, Scott
CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
To all who provided helpful input so far, thanks.
From your collective responses, I now believe it would be better to
develop an "include" list for rsyncing instead of a "exclude" list and trying to mirror the whole thing.
My real, main objective is to be able to get a config working on a local machine for FTP, Postfix, Apache, etc. then quickly getting a remote server up and running with those configs in a quick fashion. I would like to have my configuration "portable" so to speak so I may change providers on a whim if desired, and to do minimal configuration on the remote server to quickly get it to the stage and setup of my main, home box.
From your input I gather a better way to accomplish that goal would be
to have the remote hosting company turn up the server with Centos on it, then I can yum update/install the necessary packages to it, then rsync most of my software package configs to it.
I think <smile>.
Thanks again for the help. Further coaching welcome...
Best, Scott
Hi guys:
I'm about to migrate a sever to a managed server facility. I've alwau=ys used tape to backup my server, now that's not an option. I've read abut using rsync to do backups and have several scripts to do same. I believe rsync is a good solution.
I am missing some important nuiances though... I would like to have essentially a "mirror" server at my facility ( call it "master") that I can backup to, and from, completely from the other server (call it "hosted").
Obviously I have to have at least different IP addresses on "master" and "hosted", but other than that, I'd like them to be mirrors of each other. I would like to do all my configs, setup, etc. at my leisure on "master", where I have hands on control, then when ready, have "hosted" setup with a basic Centos server install, then configure it to rsync to my "master" and update the entire thing (updates and all) to my "master".
- Which files tdo I need to exclude to avoid IP address and hostname
changes?
- What caveats do I need to be aware of? Are there other files such as
'live" libraries that I cannot sync to?
- The "master" server at my facility and their server may have different
hard drive architecture (i.e. IDS and SCSI drives, different processor, etc.). As long as I use a generic Kernel (i.e. stock) that supposts the hardware on both, this shoudl not be a problem, right?
- Am I missing something, is there a better way?
Thanks, Scott
You might be able to use SystemImager (http://www.systemimager.org/) to handle this. It's designed to create an rsync based replica of a 'golden server' that can then be pushed down to one or more client machines. It has mechanisms for changing IP addresses and other networking information on the client machines. You'll want to familiarize yourself with how it excludes files from the image so you can avoid overwriting important data. Your live will be much easier if you have identical hardware, but if you're truly determined, it might be doable with reasonably similar hardware.
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