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

m (FAQ: add more than one dc)
m (Added categoy.)
 
(7 intermediate revisions by 4 users not shown)
Line 1: Line 1:
 
= Introduction =
 
= 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 Osync.
+
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 Osync replication =
+
= Information on unison + rsync replication =
  
This HowTo describes a solution for SysVol replication, that is based on Osync (rsync is required). As Compare to the rsync method, it is bidirectional. But this howto only cover two DC setup.
+
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:  
 
It have the following advantages:  
* setup is fast
+
* setup is fast done
 
* configuration is very easy
 
* configuration is very easy
* Can work with windows (Todo)
+
* Can work with windows (Please add in)
  
In this setup we will use rsync through a SSH tunnel.
+
We will use rsync through a SSH tunnel.
  
 
= Setup the SysVol replication =
 
= Setup the SysVol replication =
  
== Installation ==
+
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
  
I don't see any package but osync available on
+
Change the path if that don't fit your setup.
[https://github.com/deajan/osync]https://github.com/deajan/osync
 
 
 
== Getting Osync ==
 
At the time of writing this Osync is still at v.100pre.
 
However, you should always get a stable branch when it is available.
 
We are getting it done using master branch.
 
wget https://raw.githubusercontent.com/deajan/osync/master/osync.sh
 
chmod +x osync.sh
 
Move osync to /usr/bin/ or your preferred dir
 
mv osync.sh /usr/bin/
 
 
 
== Getting Osync Configuration ==
 
wget https://raw.githubusercontent.com/deajan/osync/master/sync.conf
 
Move it to /etc/osync/
 
mkdir /etc/osync/
 
mv sync.conf /etc/osync/sync.conf
 
  
 
=== Setup on the Domain Controller with the PDC Emulator FSMO role ===
 
=== Setup on the Domain Controller with the PDC Emulator FSMO role ===
Some assumption:
 
* You are running all command as root.
 
* rsync is installed on both server
 
* sysvol is located /var/lib/samba/sysvol on both DC1 and DC2
 
* osync is located /usr/bin/osync
 
* osync.conf is located /etc/osync/sync.conf
 
* DC1 is at DC1
 
* DC2 is at DC2 (And already join DC1)
 
* sysvolsync log is located /var/log/osync_*.log
 
* rsync must support extended ACLs
 
 
* 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!
* sysvol must be on disk which is mounted to support acl and also xattr
 
 
* 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. (Gentoo need to do <tt>eselect unison</tt> to create the link)
Change the path if that don't fit your setup.
 
  
 
==== 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 DC2
 
  ssh DC2
  
=== Osync Configuration Setup on DC1 ===
+
==== Setup ssh Control ====
Edit the /etc/osync/sync.conf and make some changes
+
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
  
#!/usr/bin/env bash
+
==== Setup Sysvolsync Log files ====
SYNC_ID="sysvol_sync"
+
Do the following on DC1 so that we can check what happen on the sync.
MASTER_SYNC_DIR="/var/lib/samba/sysvol"
+
Please include this files into to log rotate as we didn't control the log size here.
SLAVE_SYNC_DIR="ssh://root@DC2:22//var/lib/samba/sysvol"
 
SSH_RSA_PRIVATE_KEY="/root/.ssh/id_rsa"
 
PRESERVE_ACL=yes
 
PRESERVE_XATTR=yes
 
SOFT_DELETE=yes
 
DESTINATION_MAILS="your@email.com"
 
  
Osync have also backup and soft delete which will kept a copy of deleted files and folder.  
+
touch /var/log/sysvol-sync.log
You can choose to enable them.
+
chmod 640 /var/log/sysvol-sync.log
:'''Branch Fix#22 fix the soft delete issue you can get them from the url below, however, it should be check in to stable branch soon.'''
 
  
  wget https://raw.githubusercontent.com/deajan/osync/fix%2322/osync.sh
+
==== Setup Unison defaults running parameters ====
 +
Please run the following on DC1
  
Osync have one benefit as it will only send email alert if there is problem.
+
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 on DC2 ===
+
=== 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 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'''
  
* Shutdown DC2 Samba AD DC
+
ssh DC2 "cp -R --preserve=all /var/lib/samba/sysvol /var/lib/samba/"
mv /var/lib/samba/private/idmap.ldb /var/lib/samba/private/idmap.ldb.backup"
 
rm /var/cache/samba/gencache.tdb"
 
 
 
* Copy idmap.ldb from DC1 to sync the idmap.
 
* Run the following command on '''DC1'''
 
scp /var/lib/samba/private/idmap.ldb root@DC2:/var/lib/samba/private/
 
  
== 1st Try ==  
+
== 1st Trial ==  
 
What happen is we use rsync to create the directory structure with extended attributes
 
What happen is we use rsync to create the directory structure with extended attributes
 
Than unison setup copies only the extened attributes on files.
 
Than unison setup copies only the extened attributes on files.
  
<BR>Please make a '''backup''' on you sysvol just in case.
+
<BR>Please make a '''backup''' on you sysvol just in case as we are really '''TRYING''' there are no <tt>dry-run</tt>
 
+
  /usr/bin/osync.sh /etc/osync/sync.conf --dry --verbose
+
  /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
 
 
If this run successfully let remove the --dry and execute it.
 
  
/usr/bin/osync.sh /etc/osync/sync.conf --verbose
+
:'''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 ==
 
== Add to Crontab on DC1 ==
 
On DC1 run the following:
 
On DC1 run the following:
 
  crontab -e  
 
  crontab -e  
  */5 * * * * root  /usr/bin/osync.sh /etc/osync/sync.conf  --silent
+
  */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!'''
 
:'''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!'''
Line 113: Line 118:
 
:'''Warning: Please follow the steps below OR you can end up with an empty sysvol 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>
 
# Disable Cron on DC1, like Add a "#" on the line with <tt>crontab -e</tt>
# Check is any rsync or osync are currently running in <tt>ps -aux</tt> if yes, wait for it to finished OR kill it (if it is zombie)
+
# 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 .osync_workdir hash files on both DC1 and DC2 on <tt>MASTER/SLAVE_SYNC_DIR "/var/lib/samba/sysvol"</tt>
+
# Remove the hash files on both DC1 and DC2 on <tt>/root/.unison</tt>
 
# Now check your sysvol and resync
 
# Now check your sysvol and resync
 
# Confirm that everything is ok again
 
# Confirm that everything is ok again
Line 126: Line 131:
  
 
* What to do if I've more than one DC?
 
* What to do if I've more than one DC?
** By Theory, We would just make more cron jobs on DC1 and the complete sync will be perform next sync to all server. (Not tested)
+
** In Theory, We would just make more cron jobs on DC1 and the complete sync will be perform next sync to all server.
** Something like:
 
** DC1 <> DC2
 
** DC1 <> DC3
 
** DC1 <> DC2
 
  
  
 
* Why can't I simply use a distributed filesystem like GlusterFS, Lustre, etc. for SysVol?
 
* 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. Please check on the [https://lists.samba.org/archive/samba/2014-February/178546.html reply] from Samba Developer on the mailing list .
+
** 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.