Quick understanding of DRS.
Critical
Backup is one of the most critical component of CUCM, mainly because if it is down and we don't have any recent backups, we are already in a half network down situation.
Hence, it is advisable to take backup after any modification in CUCM box.
Disaster Recovery System (DRS)
Disaster recovery system performs cluster-level data backup and restore functions on Call Manager cluster.
The services responsible for backup and restore functions are DRS MA and DRS LA.
Master Agent (MA)
Master Agent service should mainly be running on Publisher node. Master Agent service is responsible to provide DRS user interface, which means that options like adding a backup devices, running manual backup etc. needs DRS MA service to be fully functional. Now, you can understand why it needs to run mainly on Publisher node :)
Local Agent (LA)
Local Agent service should be running on all CUCM nodes including Publisher node because it is LA service which is responsible to perform backup and restore functions for its servers.
Things to remember
DRS backup needs to be restored on exact same version of call manager where it was taken. For example-
I took a backup of CM version 7.1.5b(SU2), it has to be only restored on 7.1.5b(SU2).
Though it sounds very simple and logical, but I have found in past experience, people tend to forget this and end up rebuilding server.
Another point to understand is, DRS backup only restores on Publisher. For example, if you are in a migration phase from MCS server to UCS server because you have heard all good things about UCS and want to migrate your network on it. Your management is also thinking to upgrade the server to 8.X version since it is the latest in town. Now, how would you go about it?
You can bring the publisher on UCS platform using exact same version as was on MCS, say 7.1.5b(SU2) and restore the backup on publisher. Now, let's make it a bit complex.
You were away for a quick smoke and found that the 7.1.5b(SU2) DVD is no longer there, however, you still have 8.6.1 DVD with you.
What we can do here is, we can upgrade our publisher to 8.6.1 since backup was restored on it already. And
Publisher is running flawlessly with all the data in it.
But what about subscriber, you can migrate your subscriber node on UCS with direct 8.6.1 DVD installation.
Life is easy now!
References.
Backup is one of the most critical component of CUCM, mainly because if it is down and we don't have any recent backups, we are already in a half network down situation.
Hence, it is advisable to take backup after any modification in CUCM box.
Disaster Recovery System (DRS)
Disaster recovery system performs cluster-level data backup and restore functions on Call Manager cluster.
The services responsible for backup and restore functions are DRS MA and DRS LA.
Master Agent (MA)
Master Agent service should mainly be running on Publisher node. Master Agent service is responsible to provide DRS user interface, which means that options like adding a backup devices, running manual backup etc. needs DRS MA service to be fully functional. Now, you can understand why it needs to run mainly on Publisher node :)
Local Agent (LA)
Local Agent service should be running on all CUCM nodes including Publisher node because it is LA service which is responsible to perform backup and restore functions for its servers.
Things to remember
DRS backup needs to be restored on exact same version of call manager where it was taken. For example-
I took a backup of CM version 7.1.5b(SU2), it has to be only restored on 7.1.5b(SU2).
Though it sounds very simple and logical, but I have found in past experience, people tend to forget this and end up rebuilding server.
Another point to understand is, DRS backup only restores on Publisher. For example, if you are in a migration phase from MCS server to UCS server because you have heard all good things about UCS and want to migrate your network on it. Your management is also thinking to upgrade the server to 8.X version since it is the latest in town. Now, how would you go about it?
You can bring the publisher on UCS platform using exact same version as was on MCS, say 7.1.5b(SU2) and restore the backup on publisher. Now, let's make it a bit complex.
You were away for a quick smoke and found that the 7.1.5b(SU2) DVD is no longer there, however, you still have 8.6.1 DVD with you.
What we can do here is, we can upgrade our publisher to 8.6.1 since backup was restored on it already. And
Publisher is running flawlessly with all the data in it.
But what about subscriber, you can migrate your subscriber node on UCS with direct 8.6.1 DVD installation.
Life is easy now!
References.
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