EOS MGM master/slave QDB startup procedure (eos-server-4.5.9)

Site Administrators
1

With a configuration like this :

  • eos-server-4.5.9 (more or less)
  • namespace in QuarkDB (mgmofs.nslib /usr/lib64/libEosNsQuardb.so in /etc/xrd.cf.mgm
  • config file exported to quarkdb, and mgmofs.cfgtype quarkdb in /etc/xrd.cf.mgm
  • master/slave configuration (2 MGMs) and EOS_USE_QDB_MASTER=1 in /etc/sysconfig/eos_env
  • MQ MGM daemons also configured to use QuarkDB as source of information (mgmofs.qdbcluster and mgmofs.qdbpassword_file in /etc/xrd.cf.mq

Previously, with namespace in memory, I had this sequence of commands to start the MGMs :

On the master :

  systemctl start eos@master
  systemctl start eossync
  systemctl start eos@sync
  systemctl start eos@mq
  systemctl start eos@mgm

On the Slave :

 systemctl start eos@slave
  systemctl start eossync
  systemctl start eos@sync
  systemctl start eos@mq
  systemctl start eos@mgm

But now, with the namespace and config file and MQ in QuarkDB, as the 1st MGM pokes the QDB and find itself as the master, I’m note sure that the systemctl start eos@master and systemctl start eos@slave are needed.

For the Master to slave transition is a lot improved with the eos ns master other command

Also from another thread I’ve understood that the systemctl start eos@sync is no longer needed and the EOS developpers are thinking about to drop the MQ daemon.

So for the 4.5.9 version (and for many others I think), I would like to know if there is something wrong in the following starting sequence ?

On the 1st MGM to be booted (master)

  systemctl start eos@master
  systemctl start eos@mq
  systemctl start eos@mgm

Does systemctl start eos@master is still needed ?

On the 2nd MGM to be booted (slave)

  systemctl start eos@slave
  systemctl start eos@mq
  systemctl start eos@mgm

Does systemctl start eos@slave is still needed ?

And for the for the Master to slave transition (with the MQ daemons configured to use QuarkDB), after eos ns master other, is there another command to type ?

Thanks for your comments.
Denis

2

I answer to myself to some questions of this thread for the documentation (Thanks for JM for some hints), I hope this helps :

Does systemctl start eos@master is still needed ?
No, the only command needed is systemctl start eos on each MGM, no need to have systemctl start eos@master on one and systemctl start eos@slave on the other, the 1st MGM launched takes the master role by itself.

After eos ns master other , is there another command to type ?
no.

Denis

3

Hi Denis,

Sorry for missing your first post.
No, there is no other command other than eos ns master other to switch to a different master.

Cheers,
Elvin