How to merge two independent ZCS servers into one

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How to merge two independent ZCS servers into ONE

   KB 23120        Last updated on 2022-01-12  

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This article covers the following:

Case scenario: There are two separate zimbra server, not connected in any way. The aim is to move the data from one of the servers to the other.

The steps below can be used to move a server to another new server too, or to another ZCS server in multi server environment.


  • Lets call the server that the data will be moved to the "SOURCE", and the server that will move its data to the "source" the "CLIENT".
  • The "source" and the "client" must have the same hostnames prior this operation. For more information check the "Additional Content" section at the bottom of the page.
  • The OS versions of the "source" and the "client" can be different. Eg. migrate from centos to ubuntu is ok.

During the steps below, there are couple of scripts to be run. Make sure you make them executable (chmod +x before that. If you are using vim to paste the text, use :set paste before pasting, otherwise when you paste the text the formatting will be gone.


Overview of the steps:

On both servers create base directories for the migration:

# mkdir /migration
# chown zimbra.zimbra /migration

On the old server (CLIENT):

1. Become zimbra.

# su - zimbra

2. Backup the data from the "client".

2.1. Backup the domains:

cd /migration
zmprov gad > domains.txt

(open the domains.txt and remove all domains/subdomains that already exists on the "source")

2.2 Backup all admins.

cd /migration
zmprov gaaa > admins.txt

2.3 Backup all accounts.

cd /migration
zmprov -l gaa > accounts.txt

(open the file accounts.txt and remove the accounts starting with: spam,ham,virus,galsync)

2.4. Add the calendar resources to the accounts file.

zmprov gacr >> accounts.txt

2.5 Backup all distribution lists.

cd /migration
zmprov gadl > dlist.txt

2.6 Backup all members of the distribution lists.

cd /migration
mkdir dl
for i in `cat /migration/dlist.txt`; do zmprov gdlm $i > /migration/dl/$i.txt ;echo "$i"; done

4. Backup all account passwords.

cd /migration
mkdir userpass
for i in `cat accounts.txt`; do zmprov  -l ga $i userPassword | grep userPassword: | awk '{ print $2}' > userpass/$i.shadow; done

5. Backup all user,display and given names.

cd /migration
mkdir userdata
for i in `cat accounts.txt`; do zmprov ga $i  | grep -i Name: > userdata/$i.txt ; done

6. Backup all accounts data.

cd /migration
mkdir accounts
for account in `cat /migration/accounts.txt`; do /opt/zimbra/bin/zmmailbox -z -m $account -t 0 getRestURL "//?fmt=tgz" > accounts/$account.tgz ;  echo $account done; done

7. Backup aliases.

cd /migration
mkdir alias
for i in `cat accounts.txt`; do zmprov ga  $i | grep zimbraMailAlias |awk '{print $2}' > alias/$i.txt ;echo $i ;done

Remove the ones that are empty files:

find /migration/alias/* -size 0 | xargs rm -f

8. Backup user's emails that are set as "forwarding"


mkdir /tmp/script
zmprov -l gaa > /tmp/script/accounts.txt
sed -i '/galsync*/d' /tmp/script/accounts.txt
sed -i '/ham*/d' /tmp/script/accounts.txt
sed -i '/spam*/d' /tmp/script/accounts.txt
sed -i '/virus-quarantine*/d' /tmp/script/accounts.txt

   for i in `cat /tmp/script/accounts.txt`
   addresses=`zmprov ga $i zimbraMailForwardingAddress|sed '1d'|awk '{print $2}'`
   touch /tmp/script/$i
   echo -e "$addresses \n" >> /tmp/script/$i

   truncate -s -1 /tmp/script/$i


find /tmp/script -size -3c | xargs -n1 rm -v
ls -l /tmp/script | awk '{print $9}'|sed '1,2d' > /tmp/script/accounts.txt

9. Backup distribution lists aliases


mkdir /tmp/dist
zmprov gadl > /tmp/dist/distlist.txt

	for i in `cat /tmp/dist/distlist.txt`
	distlist=`zmprov gdl $i | grep zimbraMailAlias |awk '{print $2}'|sed '1d'`
	touch /tmp/dist/$i
	echo -e "$distlist \n" >> /tmp/dist/$i
	truncate -s -1 /tmp/dist/$i
find /tmp/dist -size -3c | xargs -n1 rm -v
ls -l /tmp/dist | awk '{print $9}'|sed '1,2d' > /tmp/dist/distlist.txt

10. Backup user's notes


mkdir /tmp/notes
zmprov -l gaa > /tmp/notes/accounts.txt
sed -i '/galsync*/d' /tmp/notes/accounts.txt
sed -i '/ham*/d' /tmp/notes/accounts.txt
sed -i '/spam*/d' /tmp/notes/accounts.txt
sed -i '/virus-quarantine*/d' /tmp/notes/accounts.txt

	for i in `cat /tmp/notes/accounts.txt`
	note=`zmprov ga $i zimbraNotes |sed '1d'| cut -d ":" -f2-| sed '/^$/d' |sed -e 's/^[ \t]*//'`
	touch /tmp/notes/$i
	echo "$note" >> /tmp/notes/$i
find /tmp/notes -size -3c | xargs -n1 rm -v
ls -l /tmp/notes | awk '{print $9}'|sed '1,2d' > /tmp/notes/accounts.txt

11. Backup COS (if different from the "source" server).

If you have only the default COS on the "client", but its with different settings from the COS on the "source" server, you have to rename it and then import it under different name.

Create new entry as follows:

Host: "client" server IP
Port 389 ; Protocol v3
Base DN: cn=zimbra


Level: User + Password
User DN: cn=config
Password is the output from: zmlocalconfig -s ldap_root_password

Click OK.

  • From the left Tree View, expand cos.
  • Select the COS that you want to export&move to the "source" server.
  • From the File menu line above, click on LDIF > Export Subtree > Save on the local disk.
  • Do that with all COS you want to move.

(leave the JXplorer open for the import)

12. Create files for each COS, and their respective user members.

mkdir /migration/cos_users


# The result is a file/s for each COS, and the users within this specific COS
# Note: If there are no custom created COS, there will be no users listed in the default and default_external files. That 
# means all users are in the "default" COS.
# Since the default and the default_external files will contain no users, their respective files are deleted at 
# the end. Zimbra only detect users that are not in the default COS. Thus, every non detected user is in the default COS. 

source ~/bin/zmshutil; zmsetvars

for i in `zmprov gac`
       id=`zmprov gc $i | grep -e "\bzimbraId\b"|cut -d " " -f 2`

       ldapsearch -x -H $ldap_master_url -D $zimbra_ldap_userdn -w $zimbra_ldap_password| grep -e $id -e "dn: uid=" -e mail:|grep -v Email| grep -e zimbraCOSId -B1 -A1|grep mail|awk '{print $2}' > /migration/cos_users/$i

/bin/rm -rf /migration/cos_users/default*


13. Backup Resource/s.

The resource backup is the same as the COS explained in point 8 above. The one difference is that you need to specify different "Base DN:" when you login. The Resource is type of a user, and to see the users, we need to use the following bind dn:


As you substitute the above "domain" and "com" with your specific information. The rest is the same as in point 8, as you click on the resource users in order to export them.

14. RSYNC the backed up data to the new server.

rsync -e ssh -axvzKHS  /migration/ root@

The is the IP of the "source" server.

On the new server (SOURCE)

1. Restore COS.

To import to the "source" server:

  • Create new entry in the JXplorer as in point 8, but this time specify the "source" server IP.
  • Click on the "cos"
  • LDIF > Import File > Select File > Import

Do that with all COS you want to import.

2. Restore Resource/s.

Same as restoring COS, except the difference in the binding base dn, explained above in point 10.

3. Recreate all domains.

cd /migration
for i in `cat /migration/domains.txt`; do  zmprov cd $i zimbraAuthMech zimbra ;echo $i ;done

4. Create the accounts and set the original passwords.

You may have a warning that the resource users are already created, ignore it.

# Creates the users and sets the old passwords. 
# Use dummy password "zimbra" during the user creation

if [ $(whoami) != 'zimbra' ]; then
       echo "Must be zimbra to run $0"
       exit 1;
for i in `cat $USERS`
givenName=$(grep givenName: $USERDDATA/$i.txt | cut -d ":" -f2)
displayName=$(grep displayName: $USERDDATA/$i.txt | cut -d ":" -f2)
shadowpass=$(cat $USERPASS/$i.shadow)
zmprov ca $i zimbra cn "$givenName" displayName "$displayName" givenName "$givenName" 
zmprov ma $i userPassword "$shadowpass"

5. Restore accounts data from the tgz files.

for i in `cat /migration/accounts.txt`; do zmmailbox -z -m $i postRestURL "/?fmt=tgz&resolve=skip" /migration/accounts/$i.tgz ; echo "$i done "; done

6. Add the migrated users from the "client" to their respective COS on the "source".

# The script first list the exported cos names, then iterate through all members within this cos and finally assigns the 
# user to the COS. 

for cos in `/bin/ls -1 /migration/cos_users | tr " " "\n"`
	for i in `cat /migration/cos_users/$cos`
		zmprov sac $i $cos

7. Recreate the distribution lists.

for i in `cat dlist.txt`; do zmprov cdl $i ; echo "$i done " ; done

8. Add members to the distribution lists.

# add all memebers to each of these distribution lists

if [ $(whoami) != 'zimbra' ]; then
       echo "Must be zimbra to run $0"
       exit 1;
 for i in `cat /migration/dlist.txt`
	for j in `grep -v '#' dl/$i.txt |grep '@'` 
	zmprov adlm $i $j
	echo " $j has been added to list $i"


9. Restore the aliases.


if [ $(whoami) != 'zimbra' ]; then
       echo "Must be zimbra to run $0"
       exit 1;
for i in `cat /migration/accounts.txt`
	if [ -f "alias/$i.txt" ]; then
	for j in `grep '@' /migration/alias/$i.txt`
	zmprov aaa $i $j
	echo "$i has alias $j"

10. Restore forwarding addresses


mkdir /tmp/script

  for i in `cat /tmp/script/accounts.txt`
  fwd_emails=`cat /tmp/script/$i|awk '{print}' ORS=' zimbraMailForwardingAddress '|sed 's/.\{28\}$//' `
  zmprov ma $i zimbraMailForwardingAddress $fwd_emails


11. Restore distribution list/s aliases


mkdir /tmp/dist

	for i in `cat /tmp/dist/distlist.txt`

		for j in `cat /tmp/dist/$i`

		zmprov adla $i $j



12. Restore user notes


mkdir /tmp/notes

	for i in `cat /tmp/notes/accounts.txt`

	note=`cat /tmp/notes/$i`
	zmprov ma $i zimbraNotes "$note"

13. Post steps.

  • Shut down the "client" server.
  • Fix DNS.
  • Confirm your accounts and domains are present and show active, as zimbra run: zmaccts.
  • Confirm accounts show mailbox quota usage appropriately: zmprov gqu `zmhostname`.
  • Confirm COS shows the correct data: zmprov cta
  • Send emails to test the new users.

Additional Content

Similar articles:


  • Do not depend on the OS. You can migrate from CentOS to Ubuntu. Only requirement is ZCS versions to be same.
  • Does not require running the installation script after the migration
  • Most of the process can be scripted (except the cos/resources section).

Changing the hostname.

1. Stop the flow of mail/Zimbra and take backup.

2. The new hostname must exist in the DNS before zmsetservername is run.

Note: If the box is duplicate of production server, prevent this server from affecting the production server by halting communications between test and live servers.

3. Execute the following commands:

su - zimbra
/opt/zimbra/libexec/zmsetservername -o -n 

4. Reconfigure the system for its new hostname as necessary for the operating system, (It is very important to do that AFTER step 3 - edit /etc/hosts & /etc/sysconfig/network files).

5. Reboot.

6. Recreate the certificates for the new hostname:

/opt/zimbra/bin/zmcertmgr createca -new
/opt/zimbra/bin/zmcertmgr createcrt -new -subjectAltNames <servername> -days 365  (select the other servers as subjAltNames, if its multi-server env)
/opt/zimbra/bin/zmcertmgr deploycrt self
/opt/zimbra/bin/zmcertmgr deployca
/opt/zimbra/bin/zmcertmgr viewdeployedcrt
zmcontrol restart

Additionally check:

Verified Against: Zimbra Collaboration 8.7, 8.6, 8.0 Date Created: 24/12/2016
Article ID: Date Modified: 2022-01-12

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Wiki/KB reviewed by SME1 SME2 COPY EDITOR Last edit by Vdhande
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