Moving SME to new Hardware

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Revision as of 09:35, 26 September 2008 by Mweinber (talk | contribs) (→‎Cleaning up: added a note)
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Introduction

There many ways to move a SME 7 Server installation to new hardware. This document describes a method using the Affa contrib.
Affa makes it possible to move with a minimal downtime of the production server.
In the following it is assumed that prodIP is the IP address of your production server and newIP is the IP address of the new server hardware. Replace both placeholders by your real IP addresses.

Preparation

Production server

Enable remote administration ssh access in the server-manager of prodIP. This involves setting both the 'Secure shell access' for the local network, and the 'Allow administrative command line access over secure shell' setting, which must be set to 'Yes'.
Log into the prodIP box and run an update

yum update

If packages were updated signalling post-upgrade and reboot events is required.

New hardware

Install SME Server from the latest CDROM/ISO. Assign an unused IP address (newIP) and disable DHCP.
Enable remote ssh access in the server-manager on the newIP box.

Note: From now on all further steps can be done remotely via ssh login.

Log into the newIP box and run an update

yum update

Signalling post-upgrade and reboot events is required.


Install the Affa RPM 

/usr/bin/yum install --enablerepo=smecontribs smeserver-affa

Configure Affa

db affa set prodserv job
db affa setprop prodserv remoteHostName prodIP
db affa setprop prodserv RPMCheck yes

Generate DSA keys and send the public key to the prodIP server

affa --send-key prodserv

Copying data

Run the Affa job on the newIP box 

affa --run prodserv

Depending on the amount of data and the speed of hardware and network this first job run can take a really long time.

Now view the file /var/affa/prodserv/rpms-missing.txt 

less /var/affa/prodserv/rpms-missing.txt

You will find a list of RPMs which are installed on prodIP but not on this server (newIP) and also RPMs installed with different versions. Install or update the listed RPMs. To verify, you can run the steps of this chapter again. Finally the rpms-missing.txt should not list any RPMs.

Final data synchronization

Ask your users to log off.
Log into the prodIP box and stop all services that can modify data. 

SVC='qpsmtpd sqpsmtpd crond imap pop3 imaps pop3s ftp httpd-e-smith atalk smb qmail' 
for s in $SVC; do service $s stop; done

Note: Downtime of the production server starts here

Log into the newIP box and run the Affa job again 

affa --run prodserv

This run will complete very quickly as only differences since the the last run needs to be synchronsized.

Switch over to the new hardware

Log into the prodIP box and power it off 

poweroff


Log into the newIP box and rise this server to your production server 

affa --rise --all prodserv

This action will complete very quickly as only hardlinks are used and no data is physically moved.
Now do a reboot 

reboot

Note: Downtime of the production server ends here


You now have an identical copy of your old production server running on the new hardware. Your users can now log on.

Cleaning up

Remove the Affa archives 

/bin/rm -rf /var/affa

Remove the Affa packages 

yum remove smeserver-affa perl-Filesys-DiskFree

Note: Don't forget to clean up. Otherwise you will waste disk space and see strange quota reports. See this forum thread for details.

Additional information

Performance

With this method you should be able to move a typical 50 Gbyte sized server to new hardware with downtime less than 20 minutes. The final sync and the rise time does not really depend on the total files size, but on the number of files and directories.

SME 6 Server

Although Affa was designed for SME 7, you can move a SME 6 server to a hardware with SME 7 installed. But there are a few restrictions:

  • You cannot yum update the SME 6
  • You cannot use the RPM comparision, as SME 6 doesn't have yum installed and all packages would differ anyway. Skip db affa setprop prodserv RPMCheck yes
  • You must set rsync--inplace to no:
db affa setprop prodserv rsync--inplace no
  • The command affa --rise prodserv will complain about old-style db paths. Ignore these errors. After reboot login as admin on the local console and set the new Network Interfaces manually. Reboot again.
  • You cannot work remotely.
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