Difference between revisions of "Bidirectional Rsync/Unison based SysVol replication workaround"

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= Introduction =
 
= Introduction =
 
WORK in Progress
 
 
 
Samba AD currently doesn't provide support for SysVol replication. To achive this important feature in a Multi-DC environment, until it's implemented, workarounds are necessary to keep it in sync. This HowTo provides a basic workaround solution based on rsync and unison.
 
Samba AD currently doesn't provide support for SysVol replication. To achive this important feature in a Multi-DC environment, until it's implemented, workarounds are necessary to keep it in sync. This HowTo provides a basic workaround solution based on rsync and unison.
  
Line 18: Line 15:
 
= Setup the SysVol replication =
 
= Setup the SysVol replication =
  
== Installation script ==
+
Some assumptions:
If you are using apt package manger you can try this script
+
You are running all commands as root.
[https://secure.bazuin.nl/scripts/3-setup-sysvol-bidirectional.sh]
+
rsync is located  /usr/bin/rsync
 +
sysvol is located /var/lib/samba/sysvol on both DC1 and DC2
 +
unison is located /usr/bin/unison
 +
DC1 is at DC1
 +
DC2 is at DC2
 +
sysvolsync log is located /var/log/sysvol-sync.log
  
Please thank L.v. Belle for creating this
+
Change the path if that don't fit your setup.
  
Make Change to the following to fix your need:
 
 
SETSAMBASYSVOLBASE=/var/lib/samba
 
SETSAMBASYSVOLPATH=/var/lib/samba/sysvol
 
## in Minutes
 
SETCRONTIME=5
 
SETCRONFILE=/etc/cron.d/sysvol-sync
 
SETIPDC1=""
 
SETIPDC2=""
 
 
Run it <tt>./3-setup-sysvol-bidirectional.sh</tt>
 
 
== Manually ==
 
 
=== Setup on the Domain Controller with the PDC Emulator FSMO role ===
 
=== Setup on the Domain Controller with the PDC Emulator FSMO role ===
 
 
* Install rsync by using your package manager or compile from source. Make sure, that you use a version that supports extended ACLs!
 
* Install rsync by using your package manager or compile from source. Make sure, that you use a version that supports extended ACLs!
 
* We don't need to setup rsync server.
 
* We don't need to setup rsync server.
* Install unison by using your package manager or compile from source.
+
* Install unison by using your package manager or compile from source. (Gentoo need to do <tt>eselect unison</tt> to create the link)
  
 
==== Creating SSH Public Key and ssh-copy to DC2====
 
==== Creating SSH Public Key and ssh-copy to DC2====
  ssh-keygen -t dsa
+
  ssh-keygen -t rsa
  ssh-copy-id -i ~/.ssh/id_dsa.pub root@dc2
+
  ssh-copy-id -i ~/.ssh/id_rsa.pub root@DC2
  
 
You can try to access DC2 via ssh  
 
You can try to access DC2 via ssh  
ssh $SETIPDC2
+
ssh DC2
 +
 
 +
==== Setup ssh Control ====
 +
If the remote system enforces rate limits on incoming ssh connections, unison wil fail if you try to run it this way.
 +
So we create the first ssh connection as a controlpath file in the location specified, all subsequent connections will reuse on the first connection.
 +
 
 +
mkdir ~/.ssh/ctl
 +
cat << EOF > ~/.ssh/ctl/config
 +
Host *
 +
ControlMaster auto
 +
ControlPath ~/.ssh/ctl/%h_%p_%r
 +
ControlPersist 1
 +
EOF
  
 +
==== Setup Sysvolsync Log files ====
 +
Do the following on DC1 so that we can check what happen on the sync.
 +
Please include this files into to log rotate as we didn't control the log size here.
  
 +
touch /var/log/sysvol-sync.log
 +
chmod 640 /var/log/sysvol-sync.log
  
== Setup on all other Domain Controller(s) ==
+
==== Setup Unison defaults running parameters ====
 +
Please run the following on DC1
  
* Install rsync by using your paket manager or compile from source. Make sure, that you use a version that supports extended ACLs!
+
install -o root -g root -m 0750 -d /root/.unison
 +
cat << EOF > /root/.unison/default.prf
 +
# Unison preferences file
 +
# Roots of the synchronization
 +
#
 +
# copymax & maxthreads params were set to 1 for easier troubleshooting.
 +
# Have to experiment to see if they can be increased again.
 +
root = /var/lib/samba
 +
# Note that 2 x / behind DC2, it is required
 +
root = ssh://root@DC2//var/lib/samba
 +
#
 +
# Paths to synchronize
 +
path = sysvol
 +
#
 +
#ignore = Path stats    ## ignores /var/www/stats
 +
auto=true
 +
batch=true
 +
perms=0
 +
rsync=true
 +
maxthreads=1
 +
retry=3
 +
confirmbigdeletes=false
 +
servercmd=/usr/bin/unison
 +
copythreshold=0
 +
copyprog = /usr/bin/rsync -XAavz --rsh='ssh -p 22' --inplace --compress
 +
copyprogrest = /usr/bin/rsync -XAavz --rsh='ssh -p 22' --partial --inplace --compress
 +
copyquoterem = true
 +
copymax = 1
 +
logfile = /var/log/sysvol-sync.log
 +
EOF
  
* Create a password file /usr/local/samba/etc/rsync-sysvol.secret</tt> and fill it with the password you set on the PDC for the <tt>sysvol-replication</tt> rsync account (permissions of that file must not be world-readable!):
+
=== Setup SysVol on DC2 ===
 +
* On DC2 Install rsync by using your package manager or compile from source. Make sure, that you use a version that supports extended ACLs!
 +
* On DC2 Install unison by using your package manager or compile from source. (Gentoo need to do <tt>eselect unison</tt> to create the link)
 +
* Run the following command on '''DC1'''
  
  pa$$w0rd
+
  ssh DC2 "cp -R --preserve=all /var/lib/samba/sysvol /var/lib/samba/"
  
* For replicating the SysVol folder, run the following command (<tt>--dry-run</tt> means that no modifications are actually made):
+
== 1st Trial ==
 +
What happen is we use rsync to create the directory structure with extended attributes
 +
Than unison setup copies only the extened attributes on files.
  
# rsync --dry-run -XAavz --delete-after --password-file=/usr/local/samba/etc/rsync-sysvol.secret rsync://sysvol-replication@{IP-of-you-PDC}/SysVol/ /path/to/your/sysvol/folder/
+
<BR>Please make a '''backup''' on you sysvol just in case as we are really '''TRYING''' there are no <tt>dry-run</tt>
 
   
 
   
  receiving file list ... done                                                                                                                                                                                 
+
  /usr/bin/rsync -XAavz --log-file /var/log/sysvol-sync.log --delete-after -f"+ */" -f"- *" /var/lib/samba/sysvol root@DC2:/var/lib/samba  && /usr/bin/unison &> /dev/null
created directory /usr/local/samba/var/locks/sysvol                                                                                                                                                          
+
 
./                                                                                                                                                                                                           
+
:'''Note: The path on DC2 are just /var/lib/samba which is different from DC1, it is by design, there is nothing wrong!'''
samdom.example.com/                                                                                                                                                                                           
+
 
samdom.example.com/Policies/                                                                                                                                                                                 
+
== Add to Crontab on DC1 ==
samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/                                                                                                                                           
+
On DC1 run the following:
samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/GPT.INI                                                                                                                                   
+
  crontab -e
  samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/MACHINE/                                                                                                                                  
+
  */5 * * * * root  /usr/bin/rsync -XAavz --log-file /var/log/sysvol-sync.log --delete-after -f"+ */" -f"- *" /var/lib/samba/sysvol root@DC2:/var/lib/samba  &&  /usr/bin/unison &> /dev/null
samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/MACHINE/Registry.pol                                                                                                                       
 
  samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/USER/                                                                                                                                     
 
  samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/USER/Documents & Settings/                                                                                                                
 
  samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/USER/Scripts/                                                                                                                             
 
  samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/USER/Scripts/Logoff/
 
samdom.example.com/Policies/{31B2F340-016D-11D2-945F-00C04FB984F9}/USER/Scripts/Logon/
 
samdom.example.com/Policies/{6AC1786C-016F-11D2-945F-00C04FB984F9}/
 
samdom.example.com/Policies/{6AC1786C-016F-11D2-945F-00C04FB984F9}/GPT.INI
 
  samdom.example.com/Policies/{6AC1786C-016F-11D2-945F-00C04FB984F9}/MACHINE/
 
samdom.example.com/Policies/{6AC1786C-016F-11D2-945F-00C04FB984F9}/USER/
 
samdom.example.com/scripts/
 
  samdom.example.com/scripts/logonscript.bat
 
 
sent 124 bytes  received 1064 bytes  2376.00 bytes/sec
 
total size is 1207  speedup is 1.02 (DRY RUN)
 
  
:'''Warning: Make sure that the destination folder is really your SysVol folder, because the command will replicate to the given directory and removes everything in it that isn't also on the source! You could damage your system! So check the output carefully if the replication is doing, what you expect!'''
+
:'''Warning: Make sure that the destination folder is really your SysVol folder, because the command will replicate to the given directory and sync everything in it that isn't also on the source! You could damage your system! So check the output carefully if the replication is doing, what you expect!'''
  
* If everything looks sane, run the command without the <tt>--dry-run</tt> option and let rsync do the replication.
+
= When you try to resync the folder =
 +
:'''Warning: Please follow the steps below OR you can end up with an empty sysvol folder.'''
 +
# Disable Cron on DC1, like Add a "#" on the line with <tt>crontab -e</tt>
 +
# Check is any rsync or unison are currently running in <tt>ps -aux</tt> if yes, wait for it to finished OR kill it (if it is zombie)
 +
# Remove the hash files on both DC1 and DC2 on <tt>/root/.unison</tt>
 +
# Now check your sysvol and resync
 +
# Confirm that everything is ok again
 +
# Re-enable the Cron on DC1 again
  
* To automate synchronisation, you can run the command via cron (e. g. every 5 minutes).
+
= FAQ =
  
*/5 * * * *          rsync -XAavz --delete-after --password-file=/usr/local/samba/etc/rsync-sysvol.secret rsync://sysvol-replication@{IP-of-you-PDC}/SysVol/ /path/to/your/sysvol/folder/
+
* How can I do this on windows?
 +
** I don't have an answer, please post on the mailing list
  
* Repeat these steps on every DC (except your PDC!).
 
  
 +
* What to do if I've more than one DC?
 +
** In Theory, We would just make more cron jobs on DC1 and the complete sync will be perform next sync to all server.
  
  
 +
* Why can't I simply use a distributed filesystem like GlusterFS, Lustre, etc. for SysVol?
 +
** A cluster file system with Samba requires CTDB to be able to do it safely. And CTDB and AD DC are incompatible.
  
  
= FAQ =
 
  
* How can I get multi-direction replication ?
 
** There are some testing using unsion with rsync to archive this.
 
Please check this installation script
 
https://secure.bazuin.nl/scripts/3-setup-sysvol-bidirectional.sh
 
  
  
* Why can't I simply use a distributed filesystem like GlusterFS, Lustre, etc. for SysVol?
+
----
** A cluster file system with Samba requires CTDB to be able to do it safely. And CTDB and AD DC are incompatible.
+
[[Category:Active Directory]]

Latest revision as of 21:24, 26 February 2017

Introduction

Samba AD currently doesn't provide support for SysVol replication. To achive this important feature in a Multi-DC environment, until it's implemented, workarounds are necessary to keep it in sync. This HowTo provides a basic workaround solution based on rsync and unison.

Information on unison + rsync replication

This HowTo describes a solution for SysVol replication, that is based on rsync and unison. As Compare to the rsync method, it is bidirectional. But this howto only cover two DC setup.

It have the following advantages:

  • setup is fast done
  • configuration is very easy
  • Can work with windows (Please add in)

We will use rsync through a SSH tunnel.

Setup the SysVol replication

Some assumptions:

You are running all commands as root.
rsync is located  /usr/bin/rsync
sysvol is located /var/lib/samba/sysvol on both DC1 and DC2
unison is located /usr/bin/unison
DC1 is at DC1
DC2 is at DC2
sysvolsync log is located /var/log/sysvol-sync.log

Change the path if that don't fit your setup.

Setup on the Domain Controller with the PDC Emulator FSMO role

  • Install rsync by using your package manager or compile from source. Make sure, that you use a version that supports extended ACLs!
  • We don't need to setup rsync server.
  • Install unison by using your package manager or compile from source. (Gentoo need to do eselect unison to create the link)

Creating SSH Public Key and ssh-copy to DC2

ssh-keygen -t rsa
ssh-copy-id -i ~/.ssh/id_rsa.pub root@DC2

You can try to access DC2 via ssh

ssh DC2

Setup ssh Control

If the remote system enforces rate limits on incoming ssh connections, unison wil fail if you try to run it this way. So we create the first ssh connection as a controlpath file in the location specified, all subsequent connections will reuse on the first connection.

mkdir ~/.ssh/ctl
cat << EOF > ~/.ssh/ctl/config
Host *
ControlMaster auto
ControlPath ~/.ssh/ctl/%h_%p_%r
ControlPersist 1
EOF

Setup Sysvolsync Log files

Do the following on DC1 so that we can check what happen on the sync. Please include this files into to log rotate as we didn't control the log size here.

touch /var/log/sysvol-sync.log
chmod 640 /var/log/sysvol-sync.log

Setup Unison defaults running parameters

Please run the following on DC1

install -o root -g root -m 0750 -d /root/.unison
cat << EOF > /root/.unison/default.prf
# Unison preferences file
# Roots of the synchronization
#
# copymax & maxthreads params were set to 1 for easier troubleshooting.
# Have to experiment to see if they can be increased again.
root = /var/lib/samba
# Note that 2 x / behind DC2, it is required
root = ssh://root@DC2//var/lib/samba 
# 
# Paths to synchronize
path = sysvol
#
#ignore = Path stats    ## ignores /var/www/stats
auto=true
batch=true
perms=0
rsync=true
maxthreads=1
retry=3
confirmbigdeletes=false
servercmd=/usr/bin/unison
copythreshold=0
copyprog = /usr/bin/rsync -XAavz --rsh='ssh -p 22' --inplace --compress
copyprogrest = /usr/bin/rsync -XAavz --rsh='ssh -p 22' --partial --inplace --compress
copyquoterem = true
copymax = 1
logfile = /var/log/sysvol-sync.log
EOF

Setup SysVol on DC2

  • On DC2 Install rsync by using your package manager or compile from source. Make sure, that you use a version that supports extended ACLs!
  • On DC2 Install unison by using your package manager or compile from source. (Gentoo need to do eselect unison to create the link)
  • Run the following command on DC1
ssh DC2 "cp -R --preserve=all /var/lib/samba/sysvol /var/lib/samba/"

1st Trial

What happen is we use rsync to create the directory structure with extended attributes Than unison setup copies only the extened attributes on files.


Please make a backup on you sysvol just in case as we are really TRYING there are no dry-run

/usr/bin/rsync -XAavz --log-file /var/log/sysvol-sync.log --delete-after -f"+ */" -f"- *"  /var/lib/samba/sysvol root@DC2:/var/lib/samba  &&  /usr/bin/unison  &> /dev/null
Note: The path on DC2 are just /var/lib/samba which is different from DC1, it is by design, there is nothing wrong!

Add to Crontab on DC1

On DC1 run the following:

crontab -e 
*/5 * * * * root  /usr/bin/rsync -XAavz --log-file /var/log/sysvol-sync.log --delete-after -f"+ */" -f"- *"  /var/lib/samba/sysvol root@DC2:/var/lib/samba  &&  /usr/bin/unison  &> /dev/null
Warning: Make sure that the destination folder is really your SysVol folder, because the command will replicate to the given directory and sync everything in it that isn't also on the source! You could damage your system! So check the output carefully if the replication is doing, what you expect!

When you try to resync the folder

Warning: Please follow the steps below OR you can end up with an empty sysvol folder.
  1. Disable Cron on DC1, like Add a "#" on the line with crontab -e
  2. Check is any rsync or unison are currently running in ps -aux if yes, wait for it to finished OR kill it (if it is zombie)
  3. Remove the hash files on both DC1 and DC2 on /root/.unison
  4. Now check your sysvol and resync
  5. Confirm that everything is ok again
  6. Re-enable the Cron on DC1 again

FAQ

  • How can I do this on windows?
    • I don't have an answer, please post on the mailing list


  • What to do if I've more than one DC?
    • In Theory, We would just make more cron jobs on DC1 and the complete sync will be perform next sync to all server.


  • Why can't I simply use a distributed filesystem like GlusterFS, Lustre, etc. for SysVol?
    • A cluster file system with Samba requires CTDB to be able to do it safely. And CTDB and AD DC are incompatible.